深入学习java源码之Object.writeObject()与Object.readObject()

深入学习java源码之Object.writeObject()与Object.readObject()

对象的输出流： ObjectOutputStream
对象的输入流:  ObjectInputStream

java.io.ObjectOutputStream是实现序列化的关键类，它可以将一个对象转换成二进制流，然后可以通过ObjectInputStream将二进制流还原成对象。

主要的作用是用于写入对象信息与读取对象信息。 对象信息一旦写到文件上那么对象的信息就可以做到持久化了

序列化相关的基础知识： 
1、需要序列化的类必须实现java.io.Serializable接口，否则会抛出NotSerializableException异常 
2、如果检测到反序列化后的类的serialVersionUID和对象二进制流的serialVersionUID不同，则会抛出 
异常。 
3、Java的序列化会将一个类包含的引用中所有的成员变量保存下来（深度复制），所以里面的引用类型必须也要实现java.io.Serializable接口。 
4、对于不采用默认序列化或无须序列化的成员变量，可以添加transient关键字，并不是说添加了transient关键字就一定不能序列化。 
5、每个类可以实现readObject、writeObject方法实现自己的序列化策略，即使是transient修饰的成员变量也可以手动调用ObjectOutputStream的writeInt等方法将这个成员变量序列化。

ObjectOutputStream的使用方法：

class Person implements Serializable {
    private static final long serialVersionUID = 1386583756403881124L;
    String name;
    int age;
}

public class Test {
    public static void main(String[] args) throws IOException {
        FileOutputStream fos = new FileOutputStream("D:\\out.txt");
        ObjectOutputStream oos = new ObjectOutputStream(fos);
        Person p = new Person();
        p.name = "LZF";
        p.age = 19;
        oos.writeObject(p);
        oos.close();
    }
}

ObjectOutputStream只有一个public权限的构造方法：该构造方法需要传入一个OutputStream表示将对象二进制流写入到指定的OutputStream。 

public class ObjectOutputStream extends OutputStream 
        implements ObjectOutput, ObjectStreamConstants {
    //...
}

ObjectOutputStream继承了OutputStream类，实现了ObjectOutput接口和ObjectStreamConstants接口 
ObjectStreamConstants接口并没有定义方法，其内部定义了很多byte类型常量，表示序列化后的单个字节数据的含义。

ObjectOutputStream的构造方法：

public ObjectOutputStream(OutputStream out) throws IOException {
    //检查继承权限
    verifySubclass();
    //构造一个BlockDataOutputStream用于向out写入序列化数据
    bout = new BlockDataOutputStream(out);
    //构造一个大小为10，负载因子为3的HandleTable和ReplaceTable
    handles = new HandleTable(10, (float) 3.00);
    subs = new ReplaceTable(10, (float) 3.00);
    //恒为false，除非子类调用protected构造方法
    enableOverride = false;
    writeStreamHeader();
    //将缓存模式打开，写入数据时先写入缓冲区
    bout.setBlockDataMode(true);
    if (extendedDebugInfo) {
        debugInfoStack = new DebugTraceInfoStack();
    } else {
        debugInfoStack = null;
    }
}

verifySubclass方法分析现在构造的是不是ObjectOutputStream的子类

private void verifySubclass() {
    Class cl = getClass();
    //如果构造的不是ObjectOutputStream的子类则直接返回
    if (cl == ObjectOutputStream.class)
        return;
    //否则获取安全管理器检查是否有继承ObjectOutputStream的权限
    SecurityManager sm = System.getSecurityManager();
    if (sm == null)
        return;
    //移除Caches中已经失去引用的Class对象
    processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
    //将ObjectOutputStream的子类存入Caches
    WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);

    Boolean result = Caches.subclassAudits.get(key);
    if (result == null) {
        result = Boolean.valueOf(auditSubclass(cl));
        Caches.subclassAudits.putIfAbsent(key, result);
    }
    if (result.booleanValue())
        return;
    //如果没有权限则抛出SecurityException异常
    sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
}

构造完ObjectOutputStream对象后，我们一般会随之调用writeObject(Object)方法将对象写入

public final void writeObject(Object obj) throws IOException {
    //在ObjectOutputStream中这个变量恒为false，只有子类为true
    if (enableOverride) {
        //实现为空，供子类重写用
        writeObjectOverride(obj);
        return;
    }
    try {
        writeObject0(obj, false);
    } catch (IOException ex) {
        if (depth == 0)
            writeFatalException(ex);
        throw ex;
    }
}

writeObject方法首先会检查是否是ObjectOutputStream的子类，如果是则调用writeObjectOverride方法，这个方法默认实现为空，需要子类根据实际业务需求定制序列化方法。 

具体的使用

将User类的对象序列化

 class User implements Serializable{//必须实现Serializable接口
     String uid;
     String pwd;
     public User(String _uid,String _pwd){
         this.uid = _uid;
         this.pwd = _pwd;
     }
     @Override
     public String toString() {
         return "账号:"+this.uid+" 密码:"+this.pwd;
     }
 } 
 public class Demo1 {
     public static void main(String[] args) throws IOException {
         //假设将对象信息写入到obj.txt文件中，事先已经在硬盘中建立了一个obj.txt文件
         File f = new File("F:\\obj.txt");
         writeObjec(f);
         System.out.println("OK");
     }
     //定义方法把对象的信息写到硬盘上------>对象的序列化。
     public static void writeObjec(File f) throws IOException{
         FileOutputStream outputStream = new FileOutputStream(f);//创建文件字节输出流对象
         ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
         objectOutputStream.writeObject(new User("酒香逢","123"));
         //最后记得关闭资源，objectOutputStream.close()内部已经将outputStream对象资源释放了，所以只需要关闭objectOutputStream即可
         objectOutputStream.close();
     }
 }

运行程序得到记事本中存入的信息：可见已经序列化到记事本中

2、将序列化到记事本的内容反序列化

 public class Demo1 { 
     public static void main(String[] args) throws IOException, ClassNotFoundException {
         //假设将对象信息写入到obj.txt文件中，事先已经在硬盘中建立了一个obj.txt文件
         File f = new File("F:\\obj.txt");
         //writeObjec(f);
         readObject(f);
         System.out.println("OK");
     }     
     //定义方法把对象的信息写到硬盘上------>对象的序列化。
     public static void writeObjec(File f) throws IOException{
         FileOutputStream outputStream = new FileOutputStream(f);//创建文件字节输出流对象
         ObjectOutputStream objectOutputStream = new ObjectOutputStream(outputStream);
         objectOutputStream.writeObject(new User("酒香逢","123"));
         //最后记得关闭资源，objectOutputStream.close()内部已经将outputStream对象资源释放了，所以只需要关闭objectOutputStream即可

         objectOutputStream.close();
     }
     //把文件中的对象信息读取出来-------->对象的反序列化
     public static void readObject(File f) throws IOException, ClassNotFoundException{
         FileInputStream inputStream = new FileInputStream(f);//创建文件字节输出流对象
         ObjectInputStream objectInputStream = new ObjectInputStream(inputStream);
         User user = (User)objectInputStream.readObject();
         System.out.println(user);
     }
 }

运行代码得到的结果：

对象输入输出流使用时需要注意：

1. 如果对象需要被写出到文件上，那么对象所属的类必须要实现Serializable接口。 Serializable接口没有任何的方法，是一个标识接口而已。
2. 对象的反序列化创建对象的时候并不会调用到构造方法的、（这点文中没有说到，想要验证的同学在构造方法后面加一句System.out.println("构造方法执行吗？");，实际上构造方法是不执行的，自然这句话也没有输出了）
3. serialVersionUID 是用于记录class文件的版本信息的，serialVersionUID这个数字是通过一个类的类名、成员、包名、工程名算出的一个数字。
4. 使用ObjectInputStream反序列化的时候，ObjeectInputStream会先读取文件中的serialVersionUID，然后与本地的class文件的serialVersionUID
进行对比，如果这两个id不一致，反序列则失败。
5. 如果序列化与反序列化的时候可能会修改类的成员，那么最好一开始就给这个类指定一个serialVersionUID，如果一类已经指定的serialVersionUID，然后
在序列化与反序列化的时候，jvm都不会再自己算这个 class的serialVersionUID了。
6. 如果一个对象某个数据不想被序列化到硬盘上，可以使用关键字transient修饰。
7. 如果一个类维护了另外一个类的引用，则另外一个类也需要实现Serializable接口。

 

java源码

Modifier and Type	Method and Description
protected void	annotateClass(类 cl) 子类可以实现此方法，以允许类数据存储在流中。
protected void	annotateProxyClass(类 cl) 子类可以实现这种方法来存储流中的自定义数据以及动态代理类的描述符。
void	close() 关闭流。
void	defaultWriteObject() 将当前类的非静态和非瞬态字段写入此流。
protected void	drain() 排除ObjectOutputStream中的缓冲数据。
protected boolean	enableReplaceObject(boolean enable) 启用流来替换流中的对象。
void	flush() 刷新流。
ObjectOutputStream.PutField	putFields() 检索用于缓冲要写入流的持久性字段的对象。
protected Object	replaceObject(Object obj) 该方法将允许ObjectOutputStream的可信子类在序列化期间将一个对象替换为另一个对象。
void	reset() 复位将忽略已写入流的任何对象的状态。
void	useProtocolVersion(int version) 指定在编写流时使用的流协议版本。
void	write(byte[] buf) 写入一个字节数组。
void	write(byte[] buf, int off, int len) 写入一个子字节数组。
void	write(int val) 写一个字节。
void	writeBoolean(boolean val) 写一个布尔值。
void	writeByte(int val) 写入一个8位字节。
void	writeBytes(String str) 写一个字符串作为字节序列。
void	writeChar(int val) 写一个16位的字符。
void	writeChars(String str) 写一个字符串作为一系列的字符。
protected void	writeClassDescriptor(ObjectStreamClass desc) 将指定的类描述符写入ObjectOutputStream。
void	writeDouble(double val) 写一个64位的双倍。
void	writeFields() 将缓冲的字段写入流。
void	writeFloat(float val) 写一个32位浮点数。
void	writeInt(int val) 写一个32位int。
void	writeLong(long val) 写一个64位长
void	writeObject(Object obj) 将指定的对象写入ObjectOutputStream。
protected void	writeObjectOverride(Object obj) 子类使用的方法来覆盖默认的writeObject方法。
void	writeShort(int val) 写一个16位短。
protected void	writeStreamHeader() 提供了writeStreamHeader方法，因此子类可以在流中附加或预先添加自己的头。
void	writeUnshared(Object obj) 将“非共享”对象写入ObjectOutputStream。
void	writeUTF(String str) 此字符串的原始数据写入格式为 modified UTF-8 。

package java.io;

import java.io.ObjectStreamClass.WeakClassKey;
import java.lang.ref.ReferenceQueue;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import static java.io.ObjectStreamClass.processQueue;
import java.io.SerialCallbackContext;
import sun.reflect.misc.ReflectUtil;

public class ObjectOutputStream
    extends OutputStream implements ObjectOutput, ObjectStreamConstants
{

    private static class Caches {
        /** cache of subclass security audit results */
        static final ConcurrentMap subclassAudits =
            new ConcurrentHashMap<>();

        /** queue for WeakReferences to audited subclasses */
        static final ReferenceQueue> subclassAuditsQueue =
            new ReferenceQueue<>();
    }

    /** filter stream for handling block data conversion */
    private final BlockDataOutputStream bout;
    /** obj -> wire handle map */
    private final HandleTable handles;
    /** obj -> replacement obj map */
    private final ReplaceTable subs;
    /** stream protocol version */
    private int protocol = PROTOCOL_VERSION_2;
    /** recursion depth */
    private int depth;

    /** buffer for writing primitive field values */
    private byte[] primVals;

    /** if true, invoke writeObjectOverride() instead of writeObject() */
    private final boolean enableOverride;
    /** if true, invoke replaceObject() */
    private boolean enableReplace;

    // values below valid only during upcalls to writeObject()/writeExternal()
    private SerialCallbackContext curContext;
    /** current PutField object */
    private PutFieldImpl curPut;

    /** custom storage for debug trace info */
    private final DebugTraceInfoStack debugInfoStack;

    private static final boolean extendedDebugInfo =
        java.security.AccessController.doPrivileged(
            new sun.security.action.GetBooleanAction(
                "sun.io.serialization.extendedDebugInfo")).booleanValue();

    public ObjectOutputStream(OutputStream out) throws IOException {
        verifySubclass();
        bout = new BlockDataOutputStream(out);
        handles = new HandleTable(10, (float) 3.00);
        subs = new ReplaceTable(10, (float) 3.00);
        enableOverride = false;
        writeStreamHeader();
        bout.setBlockDataMode(true);
        if (extendedDebugInfo) {
            debugInfoStack = new DebugTraceInfoStack();
        } else {
            debugInfoStack = null;
        }
    }

    protected ObjectOutputStream() throws IOException, SecurityException {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
        }
        bout = null;
        handles = null;
        subs = null;
        enableOverride = true;
        debugInfoStack = null;
    }

    public void useProtocolVersion(int version) throws IOException {
        if (handles.size() != 0) {
            // REMIND: implement better check for pristine stream?
            throw new IllegalStateException("stream non-empty");
        }
        switch (version) {
            case PROTOCOL_VERSION_1:
            case PROTOCOL_VERSION_2:
                protocol = version;
                break;

            default:
                throw new IllegalArgumentException(
                    "unknown version: " + version);
        }
    }

    public final void writeObject(Object obj) throws IOException {
        if (enableOverride) {
            writeObjectOverride(obj);
            return;
        }
        try {
            writeObject0(obj, false);
        } catch (IOException ex) {
            if (depth == 0) {
                writeFatalException(ex);
            }
            throw ex;
        }
    }

    protected void writeObjectOverride(Object obj) throws IOException {
    }

    public void writeUnshared(Object obj) throws IOException {
        try {
            writeObject0(obj, true);
        } catch (IOException ex) {
            if (depth == 0) {
                writeFatalException(ex);
            }
            throw ex;
        }
    }

    public void defaultWriteObject() throws IOException {
        SerialCallbackContext ctx = curContext;
        if (ctx == null) {
            throw new NotActiveException("not in call to writeObject");
        }
        Object curObj = ctx.getObj();
        ObjectStreamClass curDesc = ctx.getDesc();
        bout.setBlockDataMode(false);
        defaultWriteFields(curObj, curDesc);
        bout.setBlockDataMode(true);
    }

    public ObjectOutputStream.PutField putFields() throws IOException {
        if (curPut == null) {
            SerialCallbackContext ctx = curContext;
            if (ctx == null) {
                throw new NotActiveException("not in call to writeObject");
            }
            Object curObj = ctx.getObj();
            ObjectStreamClass curDesc = ctx.getDesc();
            curPut = new PutFieldImpl(curDesc);
        }
        return curPut;
    }

    public void writeFields() throws IOException {
        if (curPut == null) {
            throw new NotActiveException("no current PutField object");
        }
        bout.setBlockDataMode(false);
        curPut.writeFields();
        bout.setBlockDataMode(true);
    }

    public void reset() throws IOException {
        if (depth != 0) {
            throw new IOException("stream active");
        }
        bout.setBlockDataMode(false);
        bout.writeByte(TC_RESET);
        clear();
        bout.setBlockDataMode(true);
    }

    protected void annotateClass(Class cl) throws IOException {
    }

    protected void annotateProxyClass(Class cl) throws IOException {
    }

    protected Object replaceObject(Object obj) throws IOException {
        return obj;
    }

    protected boolean enableReplaceObject(boolean enable)
        throws SecurityException
    {
        if (enable == enableReplace) {
            return enable;
        }
        if (enable) {
            SecurityManager sm = System.getSecurityManager();
            if (sm != null) {
                sm.checkPermission(SUBSTITUTION_PERMISSION);
            }
        }
        enableReplace = enable;
        return !enableReplace;
    }

    protected void writeStreamHeader() throws IOException {
        bout.writeShort(STREAM_MAGIC);
        bout.writeShort(STREAM_VERSION);
    }

    protected void writeClassDescriptor(ObjectStreamClass desc)
        throws IOException
    {
        desc.writeNonProxy(this);
    }

    public void write(int val) throws IOException {
        bout.write(val);
    }

    public void write(byte[] buf) throws IOException {
        bout.write(buf, 0, buf.length, false);
    }

    public void write(byte[] buf, int off, int len) throws IOException {
        if (buf == null) {
            throw new NullPointerException();
        }
        int endoff = off + len;
        if (off < 0 || len < 0 || endoff > buf.length || endoff < 0) {
            throw new IndexOutOfBoundsException();
        }
        bout.write(buf, off, len, false);
    }

    public void flush() throws IOException {
        bout.flush();
    }

    protected void drain() throws IOException {
        bout.drain();
    }

    public void close() throws IOException {
        flush();
        clear();
        bout.close();
    }

    public void writeBoolean(boolean val) throws IOException {
        bout.writeBoolean(val);
    }

    public void writeByte(int val) throws IOException  {
        bout.writeByte(val);
    }

    public void writeShort(int val)  throws IOException {
        bout.writeShort(val);
    }

    public void writeChar(int val)  throws IOException {
        bout.writeChar(val);
    }

    public void writeInt(int val)  throws IOException {
        bout.writeInt(val);
    }

    public void writeLong(long val)  throws IOException {
        bout.writeLong(val);
    }

    public void writeFloat(float val) throws IOException {
        bout.writeFloat(val);
    }

    public void writeDouble(double val) throws IOException {
        bout.writeDouble(val);
    }

    public void writeBytes(String str) throws IOException {
        bout.writeBytes(str);
    }

    public void writeChars(String str) throws IOException {
        bout.writeChars(str);
    }

    public void writeUTF(String str) throws IOException {
        bout.writeUTF(str);
    }

    public static abstract class PutField {

        public abstract void put(String name, boolean val);

        public abstract void put(String name, byte val);

        public abstract void put(String name, char val);

        public abstract void put(String name, short val);

        public abstract void put(String name, int val);

        public abstract void put(String name, long val);

        public abstract void put(String name, float val);

        public abstract void put(String name, double val);

        public abstract void put(String name, Object val);

        @Deprecated
        public abstract void write(ObjectOutput out) throws IOException;
    }


    int getProtocolVersion() {
        return protocol;
    }

    void writeTypeString(String str) throws IOException {
        int handle;
        if (str == null) {
            writeNull();
        } else if ((handle = handles.lookup(str)) != -1) {
            writeHandle(handle);
        } else {
            writeString(str, false);
        }
    }

    private void verifySubclass() {
        Class cl = getClass();
        if (cl == ObjectOutputStream.class) {
            return;
        }
        SecurityManager sm = System.getSecurityManager();
        if (sm == null) {
            return;
        }
        processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
        WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
        Boolean result = Caches.subclassAudits.get(key);
        if (result == null) {
            result = Boolean.valueOf(auditSubclass(cl));
            Caches.subclassAudits.putIfAbsent(key, result);
        }
        if (result.booleanValue()) {
            return;
        }
        sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
    }

    private static boolean auditSubclass(final Class subcl) {
        Boolean result = AccessController.doPrivileged(
            new PrivilegedAction() {
                public Boolean run() {
                    for (Class cl = subcl;
                         cl != ObjectOutputStream.class;
                         cl = cl.getSuperclass())
                    {
                        try {
                            cl.getDeclaredMethod(
                                "writeUnshared", new Class[] { Object.class });
                            return Boolean.FALSE;
                        } catch (NoSuchMethodException ex) {
                        }
                        try {
                            cl.getDeclaredMethod("putFields", (Class[]) null);
                            return Boolean.FALSE;
                        } catch (NoSuchMethodException ex) {
                        }
                    }
                    return Boolean.TRUE;
                }
            }
        );
        return result.booleanValue();
    }

    private void clear() {
        subs.clear();
        handles.clear();
    }

    private void writeObject0(Object obj, boolean unshared)
        throws IOException
    {
        boolean oldMode = bout.setBlockDataMode(false);
        depth++;
        try {
            // handle previously written and non-replaceable objects
            int h;
            if ((obj = subs.lookup(obj)) == null) {
                writeNull();
                return;
            } else if (!unshared && (h = handles.lookup(obj)) != -1) {
                writeHandle(h);
                return;
            } else if (obj instanceof Class) {
                writeClass((Class) obj, unshared);
                return;
            } else if (obj instanceof ObjectStreamClass) {
                writeClassDesc((ObjectStreamClass) obj, unshared);
                return;
            }

            // check for replacement object
            Object orig = obj;
            Class cl = obj.getClass();
            ObjectStreamClass desc;
            for (;;) {
                // REMIND: skip this check for strings/arrays?
                Class repCl;
                desc = ObjectStreamClass.lookup(cl, true);
                if (!desc.hasWriteReplaceMethod() ||
                    (obj = desc.invokeWriteReplace(obj)) == null ||
                    (repCl = obj.getClass()) == cl)
                {
                    break;
                }
                cl = repCl;
            }
            if (enableReplace) {
                Object rep = replaceObject(obj);
                if (rep != obj && rep != null) {
                    cl = rep.getClass();
                    desc = ObjectStreamClass.lookup(cl, true);
                }
                obj = rep;
            }

            // if object replaced, run through original checks a second time
            if (obj != orig) {
                subs.assign(orig, obj);
                if (obj == null) {
                    writeNull();
                    return;
                } else if (!unshared && (h = handles.lookup(obj)) != -1) {
                    writeHandle(h);
                    return;
                } else if (obj instanceof Class) {
                    writeClass((Class) obj, unshared);
                    return;
                } else if (obj instanceof ObjectStreamClass) {
                    writeClassDesc((ObjectStreamClass) obj, unshared);
                    return;
                }
            }

            // remaining cases
            if (obj instanceof String) {
                writeString((String) obj, unshared);
            } else if (cl.isArray()) {
                writeArray(obj, desc, unshared);
            } else if (obj instanceof Enum) {
                writeEnum((Enum) obj, desc, unshared);
            } else if (obj instanceof Serializable) {
                writeOrdinaryObject(obj, desc, unshared);
            } else {
                if (extendedDebugInfo) {
                    throw new NotSerializableException(
                        cl.getName() + "\n" + debugInfoStack.toString());
                } else {
                    throw new NotSerializableException(cl.getName());
                }
            }
        } finally {
            depth--;
            bout.setBlockDataMode(oldMode);
        }
    }

    private void writeNull() throws IOException {
        bout.writeByte(TC_NULL);
    }

    private void writeHandle(int handle) throws IOException {
        bout.writeByte(TC_REFERENCE);
        bout.writeInt(baseWireHandle + handle);
    }

    private void writeClass(Class cl, boolean unshared) throws IOException {
        bout.writeByte(TC_CLASS);
        writeClassDesc(ObjectStreamClass.lookup(cl, true), false);
        handles.assign(unshared ? null : cl);
    }

    private void writeClassDesc(ObjectStreamClass desc, boolean unshared)
        throws IOException
    {
        int handle;
        if (desc == null) {
            writeNull();
        } else if (!unshared && (handle = handles.lookup(desc)) != -1) {
            writeHandle(handle);
        } else if (desc.isProxy()) {
            writeProxyDesc(desc, unshared);
        } else {
            writeNonProxyDesc(desc, unshared);
        }
    }

    private boolean isCustomSubclass() {
        // Return true if this class is a custom subclass of ObjectOutputStream
        return getClass().getClassLoader()
                   != ObjectOutputStream.class.getClassLoader();
    }

    private void writeProxyDesc(ObjectStreamClass desc, boolean unshared)
        throws IOException
    {
        bout.writeByte(TC_PROXYCLASSDESC);
        handles.assign(unshared ? null : desc);

        Class cl = desc.forClass();
        Class[] ifaces = cl.getInterfaces();
        bout.writeInt(ifaces.length);
        for (int i = 0; i < ifaces.length; i++) {
            bout.writeUTF(ifaces[i].getName());
        }

        bout.setBlockDataMode(true);
        if (cl != null && isCustomSubclass()) {
            ReflectUtil.checkPackageAccess(cl);
        }
        annotateProxyClass(cl);
        bout.setBlockDataMode(false);
        bout.writeByte(TC_ENDBLOCKDATA);

        writeClassDesc(desc.getSuperDesc(), false);
    }

    private void writeNonProxyDesc(ObjectStreamClass desc, boolean unshared)
        throws IOException
    {
        bout.writeByte(TC_CLASSDESC);
        handles.assign(unshared ? null : desc);

        if (protocol == PROTOCOL_VERSION_1) {
            // do not invoke class descriptor write hook with old protocol
            desc.writeNonProxy(this);
        } else {
            writeClassDescriptor(desc);
        }

        Class cl = desc.forClass();
        bout.setBlockDataMode(true);
        if (cl != null && isCustomSubclass()) {
            ReflectUtil.checkPackageAccess(cl);
        }
        annotateClass(cl);
        bout.setBlockDataMode(false);
        bout.writeByte(TC_ENDBLOCKDATA);

        writeClassDesc(desc.getSuperDesc(), false);
    }

    private void writeString(String str, boolean unshared) throws IOException {
        handles.assign(unshared ? null : str);
        long utflen = bout.getUTFLength(str);
        if (utflen <= 0xFFFF) {
            bout.writeByte(TC_STRING);
            bout.writeUTF(str, utflen);
        } else {
            bout.writeByte(TC_LONGSTRING);
            bout.writeLongUTF(str, utflen);
        }
    }

    private void writeArray(Object array,
                            ObjectStreamClass desc,
                            boolean unshared)
        throws IOException
    {
        bout.writeByte(TC_ARRAY);
        writeClassDesc(desc, false);
        handles.assign(unshared ? null : array);

        Class ccl = desc.forClass().getComponentType();
        if (ccl.isPrimitive()) {
            if (ccl == Integer.TYPE) {
                int[] ia = (int[]) array;
                bout.writeInt(ia.length);
                bout.writeInts(ia, 0, ia.length);
            } else if (ccl == Byte.TYPE) {
                byte[] ba = (byte[]) array;
                bout.writeInt(ba.length);
                bout.write(ba, 0, ba.length, true);
            } else if (ccl == Long.TYPE) {
                long[] ja = (long[]) array;
                bout.writeInt(ja.length);
                bout.writeLongs(ja, 0, ja.length);
            } else if (ccl == Float.TYPE) {
                float[] fa = (float[]) array;
                bout.writeInt(fa.length);
                bout.writeFloats(fa, 0, fa.length);
            } else if (ccl == Double.TYPE) {
                double[] da = (double[]) array;
                bout.writeInt(da.length);
                bout.writeDoubles(da, 0, da.length);
            } else if (ccl == Short.TYPE) {
                short[] sa = (short[]) array;
                bout.writeInt(sa.length);
                bout.writeShorts(sa, 0, sa.length);
            } else if (ccl == Character.TYPE) {
                char[] ca = (char[]) array;
                bout.writeInt(ca.length);
                bout.writeChars(ca, 0, ca.length);
            } else if (ccl == Boolean.TYPE) {
                boolean[] za = (boolean[]) array;
                bout.writeInt(za.length);
                bout.writeBooleans(za, 0, za.length);
            } else {
                throw new InternalError();
            }
        } else {
            Object[] objs = (Object[]) array;
            int len = objs.length;
            bout.writeInt(len);
            if (extendedDebugInfo) {
                debugInfoStack.push(
                    "array (class \"" + array.getClass().getName() +
                    "\", size: " + len  + ")");
            }
            try {
                for (int i = 0; i < len; i++) {
                    if (extendedDebugInfo) {
                        debugInfoStack.push(
                            "element of array (index: " + i + ")");
                    }
                    try {
                        writeObject0(objs[i], false);
                    } finally {
                        if (extendedDebugInfo) {
                            debugInfoStack.pop();
                        }
                    }
                }
            } finally {
                if (extendedDebugInfo) {
                    debugInfoStack.pop();
                }
            }
        }
    }

    private void writeEnum(Enum en,
                           ObjectStreamClass desc,
                           boolean unshared)
        throws IOException
    {
        bout.writeByte(TC_ENUM);
        ObjectStreamClass sdesc = desc.getSuperDesc();
        writeClassDesc((sdesc.forClass() == Enum.class) ? desc : sdesc, false);
        handles.assign(unshared ? null : en);
        writeString(en.name(), false);
    }

    private void writeOrdinaryObject(Object obj,
                                     ObjectStreamClass desc,
                                     boolean unshared)
        throws IOException
    {
        if (extendedDebugInfo) {
            debugInfoStack.push(
                (depth == 1 ? "root " : "") + "object (class \"" +
                obj.getClass().getName() + "\", " + obj.toString() + ")");
        }
        try {
            desc.checkSerialize();

            bout.writeByte(TC_OBJECT);
            writeClassDesc(desc, false);
            handles.assign(unshared ? null : obj);
            if (desc.isExternalizable() && !desc.isProxy()) {
                writeExternalData((Externalizable) obj);
            } else {
                writeSerialData(obj, desc);
            }
        } finally {
            if (extendedDebugInfo) {
                debugInfoStack.pop();
            }
        }
    }

    private void writeExternalData(Externalizable obj) throws IOException {
        PutFieldImpl oldPut = curPut;
        curPut = null;

        if (extendedDebugInfo) {
            debugInfoStack.push("writeExternal data");
        }
        SerialCallbackContext oldContext = curContext;
        try {
            curContext = null;
            if (protocol == PROTOCOL_VERSION_1) {
                obj.writeExternal(this);
            } else {
                bout.setBlockDataMode(true);
                obj.writeExternal(this);
                bout.setBlockDataMode(false);
                bout.writeByte(TC_ENDBLOCKDATA);
            }
        } finally {
            curContext = oldContext;
            if (extendedDebugInfo) {
                debugInfoStack.pop();
            }
        }

        curPut = oldPut;
    }

    private void writeSerialData(Object obj, ObjectStreamClass desc)
        throws IOException
    {
        ObjectStreamClass.ClassDataSlot[] slots = desc.getClassDataLayout();
        for (int i = 0; i < slots.length; i++) {
            ObjectStreamClass slotDesc = slots[i].desc;
            if (slotDesc.hasWriteObjectMethod()) {
                PutFieldImpl oldPut = curPut;
                curPut = null;
                SerialCallbackContext oldContext = curContext;

                if (extendedDebugInfo) {
                    debugInfoStack.push(
                        "custom writeObject data (class \"" +
                        slotDesc.getName() + "\")");
                }
                try {
                    curContext = new SerialCallbackContext(obj, slotDesc);
                    bout.setBlockDataMode(true);
                    slotDesc.invokeWriteObject(obj, this);
                    bout.setBlockDataMode(false);
                    bout.writeByte(TC_ENDBLOCKDATA);
                } finally {
                    curContext.setUsed();
                    curContext = oldContext;
                    if (extendedDebugInfo) {
                        debugInfoStack.pop();
                    }
                }

                curPut = oldPut;
            } else {
                defaultWriteFields(obj, slotDesc);
            }
        }
    }

    private void defaultWriteFields(Object obj, ObjectStreamClass desc)
        throws IOException
    {
        Class cl = desc.forClass();
        if (cl != null && obj != null && !cl.isInstance(obj)) {
            throw new ClassCastException();
        }

        desc.checkDefaultSerialize();

        int primDataSize = desc.getPrimDataSize();
        if (primVals == null || primVals.length < primDataSize) {
            primVals = new byte[primDataSize];
        }
        desc.getPrimFieldValues(obj, primVals);
        bout.write(primVals, 0, primDataSize, false);

        ObjectStreamField[] fields = desc.getFields(false);
        Object[] objVals = new Object[desc.getNumObjFields()];
        int numPrimFields = fields.length - objVals.length;
        desc.getObjFieldValues(obj, objVals);
        for (int i = 0; i < objVals.length; i++) {
            if (extendedDebugInfo) {
                debugInfoStack.push(
                    "field (class \"" + desc.getName() + "\", name: \"" +
                    fields[numPrimFields + i].getName() + "\", type: \"" +
                    fields[numPrimFields + i].getType() + "\")");
            }
            try {
                writeObject0(objVals[i],
                             fields[numPrimFields + i].isUnshared());
            } finally {
                if (extendedDebugInfo) {
                    debugInfoStack.pop();
                }
            }
        }
    }

    private void writeFatalException(IOException ex) throws IOException {
        clear();
        boolean oldMode = bout.setBlockDataMode(false);
        try {
            bout.writeByte(TC_EXCEPTION);
            writeObject0(ex, false);
            clear();
        } finally {
            bout.setBlockDataMode(oldMode);
        }
    }

    // REMIND: remove once hotspot inlines Float.floatToIntBits
    private static native void floatsToBytes(float[] src, int srcpos,
                                             byte[] dst, int dstpos,
                                             int nfloats);

    // REMIND: remove once hotspot inlines Double.doubleToLongBits
    private static native void doublesToBytes(double[] src, int srcpos,
                                              byte[] dst, int dstpos,
                                              int ndoubles);

    private class PutFieldImpl extends PutField {

        /** class descriptor describing serializable fields */
        private final ObjectStreamClass desc;
        /** primitive field values */
        private final byte[] primVals;
        /** object field values */
        private final Object[] objVals;

        PutFieldImpl(ObjectStreamClass desc) {
            this.desc = desc;
            primVals = new byte[desc.getPrimDataSize()];
            objVals = new Object[desc.getNumObjFields()];
        }

        public void put(String name, boolean val) {
            Bits.putBoolean(primVals, getFieldOffset(name, Boolean.TYPE), val);
        }

        public void put(String name, byte val) {
            primVals[getFieldOffset(name, Byte.TYPE)] = val;
        }

        public void put(String name, char val) {
            Bits.putChar(primVals, getFieldOffset(name, Character.TYPE), val);
        }

        public void put(String name, short val) {
            Bits.putShort(primVals, getFieldOffset(name, Short.TYPE), val);
        }

        public void put(String name, int val) {
            Bits.putInt(primVals, getFieldOffset(name, Integer.TYPE), val);
        }

        public void put(String name, float val) {
            Bits.putFloat(primVals, getFieldOffset(name, Float.TYPE), val);
        }

        public void put(String name, long val) {
            Bits.putLong(primVals, getFieldOffset(name, Long.TYPE), val);
        }

        public void put(String name, double val) {
            Bits.putDouble(primVals, getFieldOffset(name, Double.TYPE), val);
        }

        public void put(String name, Object val) {
            objVals[getFieldOffset(name, Object.class)] = val;
        }

        // deprecated in ObjectOutputStream.PutField
        public void write(ObjectOutput out) throws IOException {
            if (ObjectOutputStream.this != out) {
                throw new IllegalArgumentException("wrong stream");
            }
            out.write(primVals, 0, primVals.length);

            ObjectStreamField[] fields = desc.getFields(false);
            int numPrimFields = fields.length - objVals.length;
            // REMIND: warn if numPrimFields > 0?
            for (int i = 0; i < objVals.length; i++) {
                if (fields[numPrimFields + i].isUnshared()) {
                    throw new IOException("cannot write unshared object");
                }
                out.writeObject(objVals[i]);
            }
        }

        void writeFields() throws IOException {
            bout.write(primVals, 0, primVals.length, false);

            ObjectStreamField[] fields = desc.getFields(false);
            int numPrimFields = fields.length - objVals.length;
            for (int i = 0; i < objVals.length; i++) {
                if (extendedDebugInfo) {
                    debugInfoStack.push(
                        "field (class \"" + desc.getName() + "\", name: \"" +
                        fields[numPrimFields + i].getName() + "\", type: \"" +
                        fields[numPrimFields + i].getType() + "\")");
                }
                try {
                    writeObject0(objVals[i],
                                 fields[numPrimFields + i].isUnshared());
                } finally {
                    if (extendedDebugInfo) {
                        debugInfoStack.pop();
                    }
                }
            }
        }

        private int getFieldOffset(String name, Class type) {
            ObjectStreamField field = desc.getField(name, type);
            if (field == null) {
                throw new IllegalArgumentException("no such field " + name +
                                                   " with type " + type);
            }
            return field.getOffset();
        }
    }

    private static class BlockDataOutputStream
        extends OutputStream implements DataOutput
    {
        /** maximum data block length */
        private static final int MAX_BLOCK_SIZE = 1024;
        /** maximum data block header length */
        private static final int MAX_HEADER_SIZE = 5;
        /** (tunable) length of char buffer (for writing strings) */
        private static final int CHAR_BUF_SIZE = 256;

        /** buffer for writing general/block data */
        private final byte[] buf = new byte[MAX_BLOCK_SIZE];
        /** buffer for writing block data headers */
        private final byte[] hbuf = new byte[MAX_HEADER_SIZE];
        /** char buffer for fast string writes */
        private final char[] cbuf = new char[CHAR_BUF_SIZE];

        /** block data mode */
        private boolean blkmode = false;
        /** current offset into buf */
        private int pos = 0;

        /** underlying output stream */
        private final OutputStream out;
        /** loopback stream (for data writes that span data blocks) */
        private final DataOutputStream dout;

        BlockDataOutputStream(OutputStream out) {
            this.out = out;
            dout = new DataOutputStream(this);
        }

        boolean setBlockDataMode(boolean mode) throws IOException {
            if (blkmode == mode) {
                return blkmode;
            }
            drain();
            blkmode = mode;
            return !blkmode;
        }

        boolean getBlockDataMode() {
            return blkmode;
        }

        public void write(int b) throws IOException {
            if (pos >= MAX_BLOCK_SIZE) {
                drain();
            }
            buf[pos++] = (byte) b;
        }

        public void write(byte[] b) throws IOException {
            write(b, 0, b.length, false);
        }

        public void write(byte[] b, int off, int len) throws IOException {
            write(b, off, len, false);
        }

        public void flush() throws IOException {
            drain();
            out.flush();
        }

        public void close() throws IOException {
            flush();
            out.close();
        }

        void write(byte[] b, int off, int len, boolean copy)
            throws IOException
        {
            if (!(copy || blkmode)) {           // write directly
                drain();
                out.write(b, off, len);
                return;
            }

            while (len > 0) {
                if (pos >= MAX_BLOCK_SIZE) {
                    drain();
                }
                if (len >= MAX_BLOCK_SIZE && !copy && pos == 0) {
                    // avoid unnecessary copy
                    writeBlockHeader(MAX_BLOCK_SIZE);
                    out.write(b, off, MAX_BLOCK_SIZE);
                    off += MAX_BLOCK_SIZE;
                    len -= MAX_BLOCK_SIZE;
                } else {
                    int wlen = Math.min(len, MAX_BLOCK_SIZE - pos);
                    System.arraycopy(b, off, buf, pos, wlen);
                    pos += wlen;
                    off += wlen;
                    len -= wlen;
                }
            }
        }

        void drain() throws IOException {
            if (pos == 0) {
                return;
            }
            if (blkmode) {
                writeBlockHeader(pos);
            }
            out.write(buf, 0, pos);
            pos = 0;
        }

        private void writeBlockHeader(int len) throws IOException {
            if (len <= 0xFF) {
                hbuf[0] = TC_BLOCKDATA;
                hbuf[1] = (byte) len;
                out.write(hbuf, 0, 2);
            } else {
                hbuf[0] = TC_BLOCKDATALONG;
                Bits.putInt(hbuf, 1, len);
                out.write(hbuf, 0, 5);
            }
        }


        /* ----------------- primitive data output methods ----------------- */

        public void writeBoolean(boolean v) throws IOException {
            if (pos >= MAX_BLOCK_SIZE) {
                drain();
            }
            Bits.putBoolean(buf, pos++, v);
        }

        public void writeByte(int v) throws IOException {
            if (pos >= MAX_BLOCK_SIZE) {
                drain();
            }
            buf[pos++] = (byte) v;
        }

        public void writeChar(int v) throws IOException {
            if (pos + 2 <= MAX_BLOCK_SIZE) {
                Bits.putChar(buf, pos, (char) v);
                pos += 2;
            } else {
                dout.writeChar(v);
            }
        }

        public void writeShort(int v) throws IOException {
            if (pos + 2 <= MAX_BLOCK_SIZE) {
                Bits.putShort(buf, pos, (short) v);
                pos += 2;
            } else {
                dout.writeShort(v);
            }
        }

        public void writeInt(int v) throws IOException {
            if (pos + 4 <= MAX_BLOCK_SIZE) {
                Bits.putInt(buf, pos, v);
                pos += 4;
            } else {
                dout.writeInt(v);
            }
        }

        public void writeFloat(float v) throws IOException {
            if (pos + 4 <= MAX_BLOCK_SIZE) {
                Bits.putFloat(buf, pos, v);
                pos += 4;
            } else {
                dout.writeFloat(v);
            }
        }

        public void writeLong(long v) throws IOException {
            if (pos + 8 <= MAX_BLOCK_SIZE) {
                Bits.putLong(buf, pos, v);
                pos += 8;
            } else {
                dout.writeLong(v);
            }
        }

        public void writeDouble(double v) throws IOException {
            if (pos + 8 <= MAX_BLOCK_SIZE) {
                Bits.putDouble(buf, pos, v);
                pos += 8;
            } else {
                dout.writeDouble(v);
            }
        }

        public void writeBytes(String s) throws IOException {
            int endoff = s.length();
            int cpos = 0;
            int csize = 0;
            for (int off = 0; off < endoff; ) {
                if (cpos >= csize) {
                    cpos = 0;
                    csize = Math.min(endoff - off, CHAR_BUF_SIZE);
                    s.getChars(off, off + csize, cbuf, 0);
                }
                if (pos >= MAX_BLOCK_SIZE) {
                    drain();
                }
                int n = Math.min(csize - cpos, MAX_BLOCK_SIZE - pos);
                int stop = pos + n;
                while (pos < stop) {
                    buf[pos++] = (byte) cbuf[cpos++];
                }
                off += n;
            }
        }

        public void writeChars(String s) throws IOException {
            int endoff = s.length();
            for (int off = 0; off < endoff; ) {
                int csize = Math.min(endoff - off, CHAR_BUF_SIZE);
                s.getChars(off, off + csize, cbuf, 0);
                writeChars(cbuf, 0, csize);
                off += csize;
            }
        }

        public void writeUTF(String s) throws IOException {
            writeUTF(s, getUTFLength(s));
        }


        /* -------------- primitive data array output methods -------------- */
        void writeBooleans(boolean[] v, int off, int len) throws IOException {
            int endoff = off + len;
            while (off < endoff) {
                if (pos >= MAX_BLOCK_SIZE) {
                    drain();
                }
                int stop = Math.min(endoff, off + (MAX_BLOCK_SIZE - pos));
                while (off < stop) {
                    Bits.putBoolean(buf, pos++, v[off++]);
                }
            }
        }

        void writeChars(char[] v, int off, int len) throws IOException {
            int limit = MAX_BLOCK_SIZE - 2;
            int endoff = off + len;
            while (off < endoff) {
                if (pos <= limit) {
                    int avail = (MAX_BLOCK_SIZE - pos) >> 1;
                    int stop = Math.min(endoff, off + avail);
                    while (off < stop) {
                        Bits.putChar(buf, pos, v[off++]);
                        pos += 2;
                    }
                } else {
                    dout.writeChar(v[off++]);
                }
            }
        }

        void writeShorts(short[] v, int off, int len) throws IOException {
            int limit = MAX_BLOCK_SIZE - 2;
            int endoff = off + len;
            while (off < endoff) {
                if (pos <= limit) {
                    int avail = (MAX_BLOCK_SIZE - pos) >> 1;
                    int stop = Math.min(endoff, off + avail);
                    while (off < stop) {
                        Bits.putShort(buf, pos, v[off++]);
                        pos += 2;
                    }
                } else {
                    dout.writeShort(v[off++]);
                }
            }
        }

        void writeInts(int[] v, int off, int len) throws IOException {
            int limit = MAX_BLOCK_SIZE - 4;
            int endoff = off + len;
            while (off < endoff) {
                if (pos <= limit) {
                    int avail = (MAX_BLOCK_SIZE - pos) >> 2;
                    int stop = Math.min(endoff, off + avail);
                    while (off < stop) {
                        Bits.putInt(buf, pos, v[off++]);
                        pos += 4;
                    }
                } else {
                    dout.writeInt(v[off++]);
                }
            }
        }

        void writeFloats(float[] v, int off, int len) throws IOException {
            int limit = MAX_BLOCK_SIZE - 4;
            int endoff = off + len;
            while (off < endoff) {
                if (pos <= limit) {
                    int avail = (MAX_BLOCK_SIZE - pos) >> 2;
                    int chunklen = Math.min(endoff - off, avail);
                    floatsToBytes(v, off, buf, pos, chunklen);
                    off += chunklen;
                    pos += chunklen << 2;
                } else {
                    dout.writeFloat(v[off++]);
                }
            }
        }

        void writeLongs(long[] v, int off, int len) throws IOException {
            int limit = MAX_BLOCK_SIZE - 8;
            int endoff = off + len;
            while (off < endoff) {
                if (pos <= limit) {
                    int avail = (MAX_BLOCK_SIZE - pos) >> 3;
                    int stop = Math.min(endoff, off + avail);
                    while (off < stop) {
                        Bits.putLong(buf, pos, v[off++]);
                        pos += 8;
                    }
                } else {
                    dout.writeLong(v[off++]);
                }
            }
        }

        void writeDoubles(double[] v, int off, int len) throws IOException {
            int limit = MAX_BLOCK_SIZE - 8;
            int endoff = off + len;
            while (off < endoff) {
                if (pos <= limit) {
                    int avail = (MAX_BLOCK_SIZE - pos) >> 3;
                    int chunklen = Math.min(endoff - off, avail);
                    doublesToBytes(v, off, buf, pos, chunklen);
                    off += chunklen;
                    pos += chunklen << 3;
                } else {
                    dout.writeDouble(v[off++]);
                }
            }
        }

        long getUTFLength(String s) {
            int len = s.length();
            long utflen = 0;
            for (int off = 0; off < len; ) {
                int csize = Math.min(len - off, CHAR_BUF_SIZE);
                s.getChars(off, off + csize, cbuf, 0);
                for (int cpos = 0; cpos < csize; cpos++) {
                    char c = cbuf[cpos];
                    if (c >= 0x0001 && c <= 0x007F) {
                        utflen++;
                    } else if (c > 0x07FF) {
                        utflen += 3;
                    } else {
                        utflen += 2;
                    }
                }
                off += csize;
            }
            return utflen;
        }

        void writeUTF(String s, long utflen) throws IOException {
            if (utflen > 0xFFFFL) {
                throw new UTFDataFormatException();
            }
            writeShort((int) utflen);
            if (utflen == (long) s.length()) {
                writeBytes(s);
            } else {
                writeUTFBody(s);
            }
        }

        void writeLongUTF(String s) throws IOException {
            writeLongUTF(s, getUTFLength(s));
        }

        void writeLongUTF(String s, long utflen) throws IOException {
            writeLong(utflen);
            if (utflen == (long) s.length()) {
                writeBytes(s);
            } else {
                writeUTFBody(s);
            }
        }

        private void writeUTFBody(String s) throws IOException {
            int limit = MAX_BLOCK_SIZE - 3;
            int len = s.length();
            for (int off = 0; off < len; ) {
                int csize = Math.min(len - off, CHAR_BUF_SIZE);
                s.getChars(off, off + csize, cbuf, 0);
                for (int cpos = 0; cpos < csize; cpos++) {
                    char c = cbuf[cpos];
                    if (pos <= limit) {
                        if (c <= 0x007F && c != 0) {
                            buf[pos++] = (byte) c;
                        } else if (c > 0x07FF) {
                            buf[pos + 2] = (byte) (0x80 | ((c >> 0) & 0x3F));
                            buf[pos + 1] = (byte) (0x80 | ((c >> 6) & 0x3F));
                            buf[pos + 0] = (byte) (0xE0 | ((c >> 12) & 0x0F));
                            pos += 3;
                        } else {
                            buf[pos + 1] = (byte) (0x80 | ((c >> 0) & 0x3F));
                            buf[pos + 0] = (byte) (0xC0 | ((c >> 6) & 0x1F));
                            pos += 2;
                        }
                    } else {    // write one byte at a time to normalize block
                        if (c <= 0x007F && c != 0) {
                            write(c);
                        } else if (c > 0x07FF) {
                            write(0xE0 | ((c >> 12) & 0x0F));
                            write(0x80 | ((c >> 6) & 0x3F));
                            write(0x80 | ((c >> 0) & 0x3F));
                        } else {
                            write(0xC0 | ((c >> 6) & 0x1F));
                            write(0x80 | ((c >> 0) & 0x3F));
                        }
                    }
                }
                off += csize;
            }
        }
    }

    private static class HandleTable {

        /* number of mappings in table/next available handle */
        private int size;
        /* size threshold determining when to expand hash spine */
        private int threshold;
        /* factor for computing size threshold */
        private final float loadFactor;
        /* maps hash value -> candidate handle value */
        private int[] spine;
        /* maps handle value -> next candidate handle value */
        private int[] next;
        /* maps handle value -> associated object */
        private Object[] objs;

        HandleTable(int initialCapacity, float loadFactor) {
            this.loadFactor = loadFactor;
            spine = new int[initialCapacity];
            next = new int[initialCapacity];
            objs = new Object[initialCapacity];
            threshold = (int) (initialCapacity * loadFactor);
            clear();
        }

        int assign(Object obj) {
            if (size >= next.length) {
                growEntries();
            }
            if (size >= threshold) {
                growSpine();
            }
            insert(obj, size);
            return size++;
        }

        int lookup(Object obj) {
            if (size == 0) {
                return -1;
            }
            int index = hash(obj) % spine.length;
            for (int i = spine[index]; i >= 0; i = next[i]) {
                if (objs[i] == obj) {
                    return i;
                }
            }
            return -1;
        }

        void clear() {
            Arrays.fill(spine, -1);
            Arrays.fill(objs, 0, size, null);
            size = 0;
        }

        int size() {
            return size;
        }

        private void insert(Object obj, int handle) {
            int index = hash(obj) % spine.length;
            objs[handle] = obj;
            next[handle] = spine[index];
            spine[index] = handle;
        }

        private void growSpine() {
            spine = new int[(spine.length << 1) + 1];
            threshold = (int) (spine.length * loadFactor);
            Arrays.fill(spine, -1);
            for (int i = 0; i < size; i++) {
                insert(objs[i], i);
            }
        }

        private void growEntries() {
            int newLength = (next.length << 1) + 1;
            int[] newNext = new int[newLength];
            System.arraycopy(next, 0, newNext, 0, size);
            next = newNext;

            Object[] newObjs = new Object[newLength];
            System.arraycopy(objs, 0, newObjs, 0, size);
            objs = newObjs;
        }

        private int hash(Object obj) {
            return System.identityHashCode(obj) & 0x7FFFFFFF;
        }
    }

    private static class ReplaceTable {

        /* maps object -> index */
        private final HandleTable htab;
        /* maps index -> replacement object */
        private Object[] reps;

        ReplaceTable(int initialCapacity, float loadFactor) {
            htab = new HandleTable(initialCapacity, loadFactor);
            reps = new Object[initialCapacity];
        }

        void assign(Object obj, Object rep) {
            int index = htab.assign(obj);
            while (index >= reps.length) {
                grow();
            }
            reps[index] = rep;
        }

        Object lookup(Object obj) {
            int index = htab.lookup(obj);
            return (index >= 0) ? reps[index] : obj;
        }

        void clear() {
            Arrays.fill(reps, 0, htab.size(), null);
            htab.clear();
        }

        int size() {
            return htab.size();
        }

        private void grow() {
            Object[] newReps = new Object[(reps.length << 1) + 1];
            System.arraycopy(reps, 0, newReps, 0, reps.length);
            reps = newReps;
        }
    }

    private static class DebugTraceInfoStack {
        private final List stack;

        DebugTraceInfoStack() {
            stack = new ArrayList<>();
        }

        void clear() {
            stack.clear();
        }

        void pop() {
            stack.remove(stack.size()-1);
        }

        void push(String entry) {
            stack.add("\t- " + entry);
        }

        public String toString() {
            StringBuilder buffer = new StringBuilder();
            if (!stack.isEmpty()) {
                for(int i = stack.size(); i > 0; i-- ) {
                    buffer.append(stack.get(i-1) + ((i != 1) ? "\n" : ""));
                }
            }
            return buffer.toString();
        }
    }

}

 

Modifier and Type	Method and Description
int	available() 返回可以读取而不阻塞的字节数。
void	close() 关闭输入流。
void	defaultReadObject() 从此流读取当前类的非静态和非瞬态字段。
protected boolean	enableResolveObject(boolean enable) 启用流以允许从流中读取的对象被替换。
int	read() 读取一个字节的数据。
int	read(byte[] buf, int off, int len) 读入一个字节数组。
boolean	readBoolean() 读取布尔值。
byte	readByte() 读取一个8位字节。
char	readChar() 读一个16位字符。
protected ObjectStreamClass	readClassDescriptor() 从序列化流读取类描述符。
double	readDouble() 读64位双倍。
ObjectInputStream.GetField	readFields() 从流中读取持久性字段，并通过名称获取它们。
float	readFloat() 读32位浮点数。
void	readFully(byte[] buf) 读取字节，阻塞直到读取所有字节。
void	readFully(byte[] buf, int off, int len) 读取字节，阻塞直到读取所有字节。
int	readInt() 读取一个32位int。
String	readLine()已弃用 此方法无法将字节正确转换为字符。 有关详细信息和替代方案，请参阅DataInputStream。
long	readLong() 读64位长。
Object	readObject() 从ObjectInputStream读取一个对象。
protected Object	readObjectOverride() 此方法由ObjectOutputStream的受信任子类调用，该子类使用受保护的无参构造函数构造ObjectOutputStream。
short	readShort() 读取16位短。
protected void	readStreamHeader() 提供了readStreamHeader方法来允许子类读取和验证自己的流标题。
Object	readUnshared() 从ObjectInputStream读取一个“非共享”对象。
int	readUnsignedByte() 读取一个无符号的8位字节。
int	readUnsignedShort() 读取无符号16位短。
String	readUTF() 以 modified UTF-8格式读取字符串。
void	registerValidation(ObjectInputValidation obj, int prio) 在返回图之前注册要验证的对象。
protected 类	resolveClass(ObjectStreamClass desc) 加载本地类等效的指定流类描述。
protected Object	resolveObject(Object obj) 此方法将允许ObjectInputStream的受信任子类在反序列化期间将一个对象替换为另一个对象。
protected 类	resolveProxyClass(String[] interfaces) 返回一个代理类，它实现代理类描述符中命名的接口; 子类可以实现此方法从流中读取自定义数据以及动态代理类的描述符，从而允许它们为接口和代理类使用备用加载机制。
int	skipBytes(int len) 跳过字节。

package java.io;

import java.io.ObjectStreamClass.WeakClassKey;
import java.lang.ref.ReferenceQueue;
import java.lang.reflect.Array;
import java.lang.reflect.Modifier;
import java.lang.reflect.Proxy;
import java.security.AccessControlContext;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.security.PrivilegedActionException;
import java.security.PrivilegedExceptionAction;
import java.util.Arrays;
import java.util.HashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import static java.io.ObjectStreamClass.processQueue;
import sun.misc.ObjectStreamClassValidator;
import sun.misc.SharedSecrets;
import sun.misc.Unsafe;
import sun.reflect.misc.ReflectUtil;

public class ObjectInputStream
    extends InputStream implements ObjectInput, ObjectStreamConstants
{
    /** handle value representing null */
    private static final int NULL_HANDLE = -1;

    /** marker for unshared objects in internal handle table */
    private static final Object unsharedMarker = new Object();

    /** table mapping primitive type names to corresponding class objects */
    private static final HashMap> primClasses
        = new HashMap<>(8, 1.0F);
    static {
        primClasses.put("boolean", boolean.class);
        primClasses.put("byte", byte.class);
        primClasses.put("char", char.class);
        primClasses.put("short", short.class);
        primClasses.put("int", int.class);
        primClasses.put("long", long.class);
        primClasses.put("float", float.class);
        primClasses.put("double", double.class);
        primClasses.put("void", void.class);
    }

    private static class Caches {
        /** cache of subclass security audit results */
        static final ConcurrentMap subclassAudits =
            new ConcurrentHashMap<>();

        /** queue for WeakReferences to audited subclasses */
        static final ReferenceQueue> subclassAuditsQueue =
            new ReferenceQueue<>();
    }

    /** filter stream for handling block data conversion */
    private final BlockDataInputStream bin;
    /** validation callback list */
    private final ValidationList vlist;
    /** recursion depth */
    private int depth;
    /** whether stream is closed */
    private boolean closed;

    /** wire handle -> obj/exception map */
    private final HandleTable handles;
    /** scratch field for passing handle values up/down call stack */
    private int passHandle = NULL_HANDLE;
    /** flag set when at end of field value block with no TC_ENDBLOCKDATA */
    private boolean defaultDataEnd = false;

    /** buffer for reading primitive field values */
    private byte[] primVals;

    /** if true, invoke readObjectOverride() instead of readObject() */
    private final boolean enableOverride;
    /** if true, invoke resolveObject() */
    private boolean enableResolve;

    private SerialCallbackContext curContext;

    public ObjectInputStream(InputStream in) throws IOException {
        verifySubclass();
        bin = new BlockDataInputStream(in);
        handles = new HandleTable(10);
        vlist = new ValidationList();
        enableOverride = false;
        readStreamHeader();
        bin.setBlockDataMode(true);
    }

    protected ObjectInputStream() throws IOException, SecurityException {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
        }
        bin = null;
        handles = null;
        vlist = null;
        enableOverride = true;
    }

    public final Object readObject()
        throws IOException, ClassNotFoundException
    {
        if (enableOverride) {
            return readObjectOverride();
        }

        // if nested read, passHandle contains handle of enclosing object
        int outerHandle = passHandle;
        try {
            Object obj = readObject0(false);
            handles.markDependency(outerHandle, passHandle);
            ClassNotFoundException ex = handles.lookupException(passHandle);
            if (ex != null) {
                throw ex;
            }
            if (depth == 0) {
                vlist.doCallbacks();
            }
            return obj;
        } finally {
            passHandle = outerHandle;
            if (closed && depth == 0) {
                clear();
            }
        }
    }

    protected Object readObjectOverride()
        throws IOException, ClassNotFoundException
    {
        return null;
    }

    public Object readUnshared() throws IOException, ClassNotFoundException {
        // if nested read, passHandle contains handle of enclosing object
        int outerHandle = passHandle;
        try {
            Object obj = readObject0(true);
            handles.markDependency(outerHandle, passHandle);
            ClassNotFoundException ex = handles.lookupException(passHandle);
            if (ex != null) {
                throw ex;
            }
            if (depth == 0) {
                vlist.doCallbacks();
            }
            return obj;
        } finally {
            passHandle = outerHandle;
            if (closed && depth == 0) {
                clear();
            }
        }
    }

    public void defaultReadObject()
        throws IOException, ClassNotFoundException
    {
        SerialCallbackContext ctx = curContext;
        if (ctx == null) {
            throw new NotActiveException("not in call to readObject");
        }
        Object curObj = ctx.getObj();
        ObjectStreamClass curDesc = ctx.getDesc();
        bin.setBlockDataMode(false);
        defaultReadFields(curObj, curDesc);
        bin.setBlockDataMode(true);
        if (!curDesc.hasWriteObjectData()) {
            defaultDataEnd = true;
        }
        ClassNotFoundException ex = handles.lookupException(passHandle);
        if (ex != null) {
            throw ex;
        }
    }

    public ObjectInputStream.GetField readFields()
        throws IOException, ClassNotFoundException
    {
        SerialCallbackContext ctx = curContext;
        if (ctx == null) {
            throw new NotActiveException("not in call to readObject");
        }
        Object curObj = ctx.getObj();
        ObjectStreamClass curDesc = ctx.getDesc();
        bin.setBlockDataMode(false);
        GetFieldImpl getField = new GetFieldImpl(curDesc);
        getField.readFields();
        bin.setBlockDataMode(true);
        if (!curDesc.hasWriteObjectData()) {
            defaultDataEnd = true;
        }

        return getField;
    }

    public void registerValidation(ObjectInputValidation obj, int prio)
        throws NotActiveException, InvalidObjectException
    {
        if (depth == 0) {
            throw new NotActiveException("stream inactive");
        }
        vlist.register(obj, prio);
    }

    protected Class resolveClass(ObjectStreamClass desc)
        throws IOException, ClassNotFoundException
    {
        String name = desc.getName();
        try {
            return Class.forName(name, false, latestUserDefinedLoader());
        } catch (ClassNotFoundException ex) {
            Class cl = primClasses.get(name);
            if (cl != null) {
                return cl;
            } else {
                throw ex;
            }
        }
    }

    protected Class resolveProxyClass(String[] interfaces)
        throws IOException, ClassNotFoundException
    {
        ClassLoader latestLoader = latestUserDefinedLoader();
        ClassLoader nonPublicLoader = null;
        boolean hasNonPublicInterface = false;

        // define proxy in class loader of non-public interface(s), if any
        Class[] classObjs = new Class[interfaces.length];
        for (int i = 0; i < interfaces.length; i++) {
            Class cl = Class.forName(interfaces[i], false, latestLoader);
            if ((cl.getModifiers() & Modifier.PUBLIC) == 0) {
                if (hasNonPublicInterface) {
                    if (nonPublicLoader != cl.getClassLoader()) {
                        throw new IllegalAccessError(
                            "conflicting non-public interface class loaders");
                    }
                } else {
                    nonPublicLoader = cl.getClassLoader();
                    hasNonPublicInterface = true;
                }
            }
            classObjs[i] = cl;
        }
        try {
            return Proxy.getProxyClass(
                hasNonPublicInterface ? nonPublicLoader : latestLoader,
                classObjs);
        } catch (IllegalArgumentException e) {
            throw new ClassNotFoundException(null, e);
        }
    }

    protected Object resolveObject(Object obj) throws IOException {
        return obj;
    }

    protected boolean enableResolveObject(boolean enable)
        throws SecurityException
    {
        if (enable == enableResolve) {
            return enable;
        }
        if (enable) {
            SecurityManager sm = System.getSecurityManager();
            if (sm != null) {
                sm.checkPermission(SUBSTITUTION_PERMISSION);
            }
        }
        enableResolve = enable;
        return !enableResolve;
    }

    protected void readStreamHeader()
        throws IOException, StreamCorruptedException
    {
        short s0 = bin.readShort();
        short s1 = bin.readShort();
        if (s0 != STREAM_MAGIC || s1 != STREAM_VERSION) {
            throw new StreamCorruptedException(
                String.format("invalid stream header: %04X%04X", s0, s1));
        }
    }

    protected ObjectStreamClass readClassDescriptor()
        throws IOException, ClassNotFoundException
    {
        ObjectStreamClass desc = new ObjectStreamClass();
        desc.readNonProxy(this);
        return desc;
    }

    public int read() throws IOException {
        return bin.read();
    }

    public int read(byte[] buf, int off, int len) throws IOException {
        if (buf == null) {
            throw new NullPointerException();
        }
        int endoff = off + len;
        if (off < 0 || len < 0 || endoff > buf.length || endoff < 0) {
            throw new IndexOutOfBoundsException();
        }
        return bin.read(buf, off, len, false);
    }

    public int available() throws IOException {
        return bin.available();
    }

    public void close() throws IOException {
        closed = true;
        if (depth == 0) {
            clear();
        }
        bin.close();
    }

    public boolean readBoolean() throws IOException {
        return bin.readBoolean();
    }

    public byte readByte() throws IOException  {
        return bin.readByte();
    }

    public int readUnsignedByte()  throws IOException {
        return bin.readUnsignedByte();
    }

    public char readChar()  throws IOException {
        return bin.readChar();
    }

    public short readShort()  throws IOException {
        return bin.readShort();
    }

    public int readUnsignedShort() throws IOException {
        return bin.readUnsignedShort();
    }

    public int readInt()  throws IOException {
        return bin.readInt();
    }

    public long readLong()  throws IOException {
        return bin.readLong();
    }

    public float readFloat() throws IOException {
        return bin.readFloat();
    }

    public double readDouble() throws IOException {
        return bin.readDouble();
    }

    public void readFully(byte[] buf) throws IOException {
        bin.readFully(buf, 0, buf.length, false);
    }

    public void readFully(byte[] buf, int off, int len) throws IOException {
        int endoff = off + len;
        if (off < 0 || len < 0 || endoff > buf.length || endoff < 0) {
            throw new IndexOutOfBoundsException();
        }
        bin.readFully(buf, off, len, false);
    }

    public int skipBytes(int len) throws IOException {
        return bin.skipBytes(len);
    }

    @Deprecated
    public String readLine() throws IOException {
        return bin.readLine();
    }

    public String readUTF() throws IOException {
        return bin.readUTF();
    }

    public static abstract class GetField {

        public abstract ObjectStreamClass getObjectStreamClass();

        public abstract boolean defaulted(String name) throws IOException;

        public abstract boolean get(String name, boolean val)
            throws IOException;

        public abstract byte get(String name, byte val) throws IOException;

        public abstract char get(String name, char val) throws IOException;

        public abstract short get(String name, short val) throws IOException;

        public abstract int get(String name, int val) throws IOException;

        public abstract long get(String name, long val) throws IOException;

        public abstract float get(String name, float val) throws IOException;

        public abstract double get(String name, double val) throws IOException;

        public abstract Object get(String name, Object val) throws IOException;
    }

    private void verifySubclass() {
        Class cl = getClass();
        if (cl == ObjectInputStream.class) {
            return;
        }
        SecurityManager sm = System.getSecurityManager();
        if (sm == null) {
            return;
        }
        processQueue(Caches.subclassAuditsQueue, Caches.subclassAudits);
        WeakClassKey key = new WeakClassKey(cl, Caches.subclassAuditsQueue);
        Boolean result = Caches.subclassAudits.get(key);
        if (result == null) {
            result = Boolean.valueOf(auditSubclass(cl));
            Caches.subclassAudits.putIfAbsent(key, result);
        }
        if (result.booleanValue()) {
            return;
        }
        sm.checkPermission(SUBCLASS_IMPLEMENTATION_PERMISSION);
    }

    private static boolean auditSubclass(final Class subcl) {
        Boolean result = AccessController.doPrivileged(
            new PrivilegedAction() {
                public Boolean run() {
                    for (Class cl = subcl;
                         cl != ObjectInputStream.class;
                         cl = cl.getSuperclass())
                    {
                        try {
                            cl.getDeclaredMethod(
                                "readUnshared", (Class[]) null);
                            return Boolean.FALSE;
                        } catch (NoSuchMethodException ex) {
                        }
                        try {
                            cl.getDeclaredMethod("readFields", (Class[]) null);
                            return Boolean.FALSE;
                        } catch (NoSuchMethodException ex) {
                        }
                    }
                    return Boolean.TRUE;
                }
            }
        );
        return result.booleanValue();
    }

    private void clear() {
        handles.clear();
        vlist.clear();
    }

    private Object readObject0(boolean unshared) throws IOException {
        boolean oldMode = bin.getBlockDataMode();
        if (oldMode) {
            int remain = bin.currentBlockRemaining();
            if (remain > 0) {
                throw new OptionalDataException(remain);
            } else if (defaultDataEnd) {
                throw new OptionalDataException(true);
            }
            bin.setBlockDataMode(false);
        }

        byte tc;
        while ((tc = bin.peekByte()) == TC_RESET) {
            bin.readByte();
            handleReset();
        }

        depth++;
        try {
            switch (tc) {
                case TC_NULL:
                    return readNull();

                case TC_REFERENCE:
                    return readHandle(unshared);

                case TC_CLASS:
                    return readClass(unshared);

                case TC_CLASSDESC:
                case TC_PROXYCLASSDESC:
                    return readClassDesc(unshared);

                case TC_STRING:
                case TC_LONGSTRING:
                    return checkResolve(readString(unshared));

                case TC_ARRAY:
                    return checkResolve(readArray(unshared));

                case TC_ENUM:
                    return checkResolve(readEnum(unshared));

                case TC_OBJECT:
                    return checkResolve(readOrdinaryObject(unshared));

                case TC_EXCEPTION:
                    IOException ex = readFatalException();
                    throw new WriteAbortedException("writing aborted", ex);

                case TC_BLOCKDATA:
                case TC_BLOCKDATALONG:
                    if (oldMode) {
                        bin.setBlockDataMode(true);
                        bin.peek();             // force header read
                        throw new OptionalDataException(
                            bin.currentBlockRemaining());
                    } else {
                        throw new StreamCorruptedException(
                            "unexpected block data");
                    }

                case TC_ENDBLOCKDATA:
                    if (oldMode) {
                        throw new OptionalDataException(true);
                    } else {
                        throw new StreamCorruptedException(
                            "unexpected end of block data");
                    }

                default:
                    throw new StreamCorruptedException(
                        String.format("invalid type code: %02X", tc));
            }
        } finally {
            depth--;
            bin.setBlockDataMode(oldMode);
        }
    }

    private Object checkResolve(Object obj) throws IOException {
        if (!enableResolve || handles.lookupException(passHandle) != null) {
            return obj;
        }
        Object rep = resolveObject(obj);
        if (rep != obj) {
            handles.setObject(passHandle, rep);
        }
        return rep;
    }

    String readTypeString() throws IOException {
        int oldHandle = passHandle;
        try {
            byte tc = bin.peekByte();
            switch (tc) {
                case TC_NULL:
                    return (String) readNull();

                case TC_REFERENCE:
                    return (String) readHandle(false);

                case TC_STRING:
                case TC_LONGSTRING:
                    return readString(false);

                default:
                    throw new StreamCorruptedException(
                        String.format("invalid type code: %02X", tc));
            }
        } finally {
            passHandle = oldHandle;
        }
    }

    private Object readNull() throws IOException {
        if (bin.readByte() != TC_NULL) {
            throw new InternalError();
        }
        passHandle = NULL_HANDLE;
        return null;
    }

    private Object readHandle(boolean unshared) throws IOException {
        if (bin.readByte() != TC_REFERENCE) {
            throw new InternalError();
        }
        passHandle = bin.readInt() - baseWireHandle;
        if (passHandle < 0 || passHandle >= handles.size()) {
            throw new StreamCorruptedException(
                String.format("invalid handle value: %08X", passHandle +
                baseWireHandle));
        }
        if (unshared) {
            // REMIND: what type of exception to throw here?
            throw new InvalidObjectException(
                "cannot read back reference as unshared");
        }

        Object obj = handles.lookupObject(passHandle);
        if (obj == unsharedMarker) {
            // REMIND: what type of exception to throw here?
            throw new InvalidObjectException(
                "cannot read back reference to unshared object");
        }
        return obj;
    }

    private Class readClass(boolean unshared) throws IOException {
        if (bin.readByte() != TC_CLASS) {
            throw new InternalError();
        }
        ObjectStreamClass desc = readClassDesc(false);
        Class cl = desc.forClass();
        passHandle = handles.assign(unshared ? unsharedMarker : cl);

        ClassNotFoundException resolveEx = desc.getResolveException();
        if (resolveEx != null) {
            handles.markException(passHandle, resolveEx);
        }

        handles.finish(passHandle);
        return cl;
    }

    private ObjectStreamClass readClassDesc(boolean unshared)
        throws IOException
    {
        byte tc = bin.peekByte();
        ObjectStreamClass descriptor;
        switch (tc) {
            case TC_NULL:
                descriptor = (ObjectStreamClass) readNull();
                break;
            case TC_REFERENCE:
                descriptor = (ObjectStreamClass) readHandle(unshared);
                break;
            case TC_PROXYCLASSDESC:
                descriptor = readProxyDesc(unshared);
                break;
            case TC_CLASSDESC:
                descriptor = readNonProxyDesc(unshared);
                break;
            default:
                throw new StreamCorruptedException(
                    String.format("invalid type code: %02X", tc));
        }
        if (descriptor != null) {
            validateDescriptor(descriptor);
        }
        return descriptor;
    }

    private boolean isCustomSubclass() {
        // Return true if this class is a custom subclass of ObjectInputStream
        return getClass().getClassLoader()
                    != ObjectInputStream.class.getClassLoader();
    }

    private ObjectStreamClass readProxyDesc(boolean unshared)
        throws IOException
    {
        if (bin.readByte() != TC_PROXYCLASSDESC) {
            throw new InternalError();
        }

        ObjectStreamClass desc = new ObjectStreamClass();
        int descHandle = handles.assign(unshared ? unsharedMarker : desc);
        passHandle = NULL_HANDLE;

        int numIfaces = bin.readInt();
        String[] ifaces = new String[numIfaces];
        for (int i = 0; i < numIfaces; i++) {
            ifaces[i] = bin.readUTF();
        }

        Class cl = null;
        ClassNotFoundException resolveEx = null;
        bin.setBlockDataMode(true);
        try {
            if ((cl = resolveProxyClass(ifaces)) == null) {
                resolveEx = new ClassNotFoundException("null class");
            } else if (!Proxy.isProxyClass(cl)) {
                throw new InvalidClassException("Not a proxy");
            } else {
                // ReflectUtil.checkProxyPackageAccess makes a test
                // equivalent to isCustomSubclass so there's no need
                // to condition this call to isCustomSubclass == true here.
                ReflectUtil.checkProxyPackageAccess(
                        getClass().getClassLoader(),
                        cl.getInterfaces());
            }
        } catch (ClassNotFoundException ex) {
            resolveEx = ex;
        }
        skipCustomData();

        desc.initProxy(cl, resolveEx, readClassDesc(false));

        handles.finish(descHandle);
        passHandle = descHandle;
        return desc;
    }

    private ObjectStreamClass readNonProxyDesc(boolean unshared)
        throws IOException
    {
        if (bin.readByte() != TC_CLASSDESC) {
            throw new InternalError();
        }

        ObjectStreamClass desc = new ObjectStreamClass();
        int descHandle = handles.assign(unshared ? unsharedMarker : desc);
        passHandle = NULL_HANDLE;

        ObjectStreamClass readDesc = null;
        try {
            readDesc = readClassDescriptor();
        } catch (ClassNotFoundException ex) {
            throw (IOException) new InvalidClassException(
                "failed to read class descriptor").initCause(ex);
        }

        Class cl = null;
        ClassNotFoundException resolveEx = null;
        bin.setBlockDataMode(true);
        final boolean checksRequired = isCustomSubclass();
        try {
            if ((cl = resolveClass(readDesc)) == null) {
                resolveEx = new ClassNotFoundException("null class");
            } else if (checksRequired) {
                ReflectUtil.checkPackageAccess(cl);
            }
        } catch (ClassNotFoundException ex) {
            resolveEx = ex;
        }
        skipCustomData();

        desc.initNonProxy(readDesc, cl, resolveEx, readClassDesc(false));

        handles.finish(descHandle);
        passHandle = descHandle;
        return desc;
    }

    private String readString(boolean unshared) throws IOException {
        String str;
        byte tc = bin.readByte();
        switch (tc) {
            case TC_STRING:
                str = bin.readUTF();
                break;

            case TC_LONGSTRING:
                str = bin.readLongUTF();
                break;

            default:
                throw new StreamCorruptedException(
                    String.format("invalid type code: %02X", tc));
        }
        passHandle = handles.assign(unshared ? unsharedMarker : str);
        handles.finish(passHandle);
        return str;
    }

    private Object readArray(boolean unshared) throws IOException {
        if (bin.readByte() != TC_ARRAY) {
            throw new InternalError();
        }

        ObjectStreamClass desc = readClassDesc(false);
        int len = bin.readInt();

        Object array = null;
        Class cl, ccl = null;
        if ((cl = desc.forClass()) != null) {
            ccl = cl.getComponentType();
            array = Array.newInstance(ccl, len);
        }

        int arrayHandle = handles.assign(unshared ? unsharedMarker : array);
        ClassNotFoundException resolveEx = desc.getResolveException();
        if (resolveEx != null) {
            handles.markException(arrayHandle, resolveEx);
        }

        if (ccl == null) {
            for (int i = 0; i < len; i++) {
                readObject0(false);
            }
        } else if (ccl.isPrimitive()) {
            if (ccl == Integer.TYPE) {
                bin.readInts((int[]) array, 0, len);
            } else if (ccl == Byte.TYPE) {
                bin.readFully((byte[]) array, 0, len, true);
            } else if (ccl == Long.TYPE) {
                bin.readLongs((long[]) array, 0, len);
            } else if (ccl == Float.TYPE) {
                bin.readFloats((float[]) array, 0, len);
            } else if (ccl == Double.TYPE) {
                bin.readDoubles((double[]) array, 0, len);
            } else if (ccl == Short.TYPE) {
                bin.readShorts((short[]) array, 0, len);
            } else if (ccl == Character.TYPE) {
                bin.readChars((char[]) array, 0, len);
            } else if (ccl == Boolean.TYPE) {
                bin.readBooleans((boolean[]) array, 0, len);
            } else {
                throw new InternalError();
            }
        } else {
            Object[] oa = (Object[]) array;
            for (int i = 0; i < len; i++) {
                oa[i] = readObject0(false);
                handles.markDependency(arrayHandle, passHandle);
            }
        }

        handles.finish(arrayHandle);
        passHandle = arrayHandle;
        return array;
    }

    private Enum readEnum(boolean unshared) throws IOException {
        if (bin.readByte() != TC_ENUM) {
            throw new InternalError();
        }

        ObjectStreamClass desc = readClassDesc(false);
        if (!desc.isEnum()) {
            throw new InvalidClassException("non-enum class: " + desc);
        }

        int enumHandle = handles.assign(unshared ? unsharedMarker : null);
        ClassNotFoundException resolveEx = desc.getResolveException();
        if (resolveEx != null) {
            handles.markException(enumHandle, resolveEx);
        }

        String name = readString(false);
        Enum result = null;
        Class cl = desc.forClass();
        if (cl != null) {
            try {
                @SuppressWarnings("unchecked")
                Enum en = Enum.valueOf((Class)cl, name);
                result = en;
            } catch (IllegalArgumentException ex) {
                throw (IOException) new InvalidObjectException(
                    "enum constant " + name + " does not exist in " +
                    cl).initCause(ex);
            }
            if (!unshared) {
                handles.setObject(enumHandle, result);
            }
        }

        handles.finish(enumHandle);
        passHandle = enumHandle;
        return result;
    }

    private Object readOrdinaryObject(boolean unshared)
        throws IOException
    {
        if (bin.readByte() != TC_OBJECT) {
            throw new InternalError();
        }

        ObjectStreamClass desc = readClassDesc(false);
        desc.checkDeserialize();

        Class cl = desc.forClass();
        if (cl == String.class || cl == Class.class
                || cl == ObjectStreamClass.class) {
            throw new InvalidClassException("invalid class descriptor");
        }

        Object obj;
        try {
            obj = desc.isInstantiable() ? desc.newInstance() : null;
        } catch (Exception ex) {
            throw (IOException) new InvalidClassException(
                desc.forClass().getName(),
                "unable to create instance").initCause(ex);
        }

        passHandle = handles.assign(unshared ? unsharedMarker : obj);
        ClassNotFoundException resolveEx = desc.getResolveException();
        if (resolveEx != null) {
            handles.markException(passHandle, resolveEx);
        }

        if (desc.isExternalizable()) {
            readExternalData((Externalizable) obj, desc);
        } else {
            readSerialData(obj, desc);
        }

        handles.finish(passHandle);

        if (obj != null &&
            handles.lookupException(passHandle) == null &&
            desc.hasReadResolveMethod())
        {
            Object rep = desc.invokeReadResolve(obj);
            if (unshared && rep.getClass().isArray()) {
                rep = cloneArray(rep);
            }
            if (rep != obj) {
                handles.setObject(passHandle, obj = rep);
            }
        }

        return obj;
    }

    private void readExternalData(Externalizable obj, ObjectStreamClass desc)
        throws IOException
    {
        SerialCallbackContext oldContext = curContext;
        if (oldContext != null)
            oldContext.check();
        curContext = null;
        try {
            boolean blocked = desc.hasBlockExternalData();
            if (blocked) {
                bin.setBlockDataMode(true);
            }
            if (obj != null) {
                try {
                    obj.readExternal(this);
                } catch (ClassNotFoundException ex) {
                     handles.markException(passHandle, ex);
                }
            }
            if (blocked) {
                skipCustomData();
            }
        } finally {
            if (oldContext != null)
                oldContext.check();
            curContext = oldContext;
        }
    }

    private void readSerialData(Object obj, ObjectStreamClass desc)
        throws IOException
    {
        ObjectStreamClass.ClassDataSlot[] slots = desc.getClassDataLayout();
        for (int i = 0; i < slots.length; i++) {
            ObjectStreamClass slotDesc = slots[i].desc;

            if (slots[i].hasData) {
                if (obj == null || handles.lookupException(passHandle) != null) {
                    defaultReadFields(null, slotDesc); // skip field values
                } else if (slotDesc.hasReadObjectMethod()) {
                    ThreadDeath t = null;
                    boolean reset = false;
                    SerialCallbackContext oldContext = curContext;
                    if (oldContext != null)
                        oldContext.check();
                    try {
                        curContext = new SerialCallbackContext(obj, slotDesc);

                        bin.setBlockDataMode(true);
                        slotDesc.invokeReadObject(obj, this);
                    } catch (ClassNotFoundException ex) {
                        handles.markException(passHandle, ex);
                    } finally {
                        do {
                            try {
                                curContext.setUsed();
                                if (oldContext!= null)
                                    oldContext.check();
                                curContext = oldContext;
                                reset = true;
                            } catch (ThreadDeath x) {
                                t = x;  // defer until reset is true
                            }
                        } while (!reset);
                        if (t != null)
                            throw t;
                    }
                    defaultDataEnd = false;
                } else {
                    defaultReadFields(obj, slotDesc);
                    }

                if (slotDesc.hasWriteObjectData()) {
                    skipCustomData();
                } else {
                    bin.setBlockDataMode(false);
                }
            } else {
                if (obj != null &&
                    slotDesc.hasReadObjectNoDataMethod() &&
                    handles.lookupException(passHandle) == null)
                {
                    slotDesc.invokeReadObjectNoData(obj);
                }
            }
        }
            }

    private void skipCustomData() throws IOException {
        int oldHandle = passHandle;
        for (;;) {
            if (bin.getBlockDataMode()) {
                bin.skipBlockData();
                bin.setBlockDataMode(false);
            }
            switch (bin.peekByte()) {
                case TC_BLOCKDATA:
                case TC_BLOCKDATALONG:
                    bin.setBlockDataMode(true);
                    break;

                case TC_ENDBLOCKDATA:
                    bin.readByte();
                    passHandle = oldHandle;
                    return;

                default:
                    readObject0(false);
                    break;
            }
        }
    }

    private void defaultReadFields(Object obj, ObjectStreamClass desc)
        throws IOException
    {
        Class cl = desc.forClass();
        if (cl != null && obj != null && !cl.isInstance(obj)) {
            throw new ClassCastException();
        }

        int primDataSize = desc.getPrimDataSize();
        if (primVals == null || primVals.length < primDataSize) {
            primVals = new byte[primDataSize];
        }
            bin.readFully(primVals, 0, primDataSize, false);
        if (obj != null) {
            desc.setPrimFieldValues(obj, primVals);
        }

            int objHandle = passHandle;
            ObjectStreamField[] fields = desc.getFields(false);
        Object[] objVals = new Object[desc.getNumObjFields()];
            int numPrimFields = fields.length - objVals.length;
            for (int i = 0; i < objVals.length; i++) {
                ObjectStreamField f = fields[numPrimFields + i];
                objVals[i] = readObject0(f.isUnshared());
                if (f.getField() != null) {
                    handles.markDependency(objHandle, passHandle);
                }
            }
        if (obj != null) {
            desc.setObjFieldValues(obj, objVals);
        }
            passHandle = objHandle;
        }

    private IOException readFatalException() throws IOException {
        if (bin.readByte() != TC_EXCEPTION) {
            throw new InternalError();
        }
        clear();
        return (IOException) readObject0(false);
    }

    private void handleReset() throws StreamCorruptedException {
        if (depth > 0) {
            throw new StreamCorruptedException(
                "unexpected reset; recursion depth: " + depth);
        }
        clear();
    }

    // REMIND: remove once hotspot inlines Float.intBitsToFloat
    private static native void bytesToFloats(byte[] src, int srcpos,
                                             float[] dst, int dstpos,
                                             int nfloats);

    // REMIND: remove once hotspot inlines Double.longBitsToDouble
    private static native void bytesToDoubles(byte[] src, int srcpos,
                                              double[] dst, int dstpos,
                                              int ndoubles);

    private static ClassLoader latestUserDefinedLoader() {
        return sun.misc.VM.latestUserDefinedLoader();
    }

    private class GetFieldImpl extends GetField {

        /** class descriptor describing serializable fields */
        private final ObjectStreamClass desc;
        /** primitive field values */
        private final byte[] primVals;
        /** object field values */
        private final Object[] objVals;
        /** object field value handles */
        private final int[] objHandles;

        GetFieldImpl(ObjectStreamClass desc) {
            this.desc = desc;
            primVals = new byte[desc.getPrimDataSize()];
            objVals = new Object[desc.getNumObjFields()];
            objHandles = new int[objVals.length];
        }

        public ObjectStreamClass getObjectStreamClass() {
            return desc;
        }

        public boolean defaulted(String name) throws IOException {
            return (getFieldOffset(name, null) < 0);
        }

        public boolean get(String name, boolean val) throws IOException {
            int off = getFieldOffset(name, Boolean.TYPE);
            return (off >= 0) ? Bits.getBoolean(primVals, off) : val;
        }

        public byte get(String name, byte val) throws IOException {
            int off = getFieldOffset(name, Byte.TYPE);
            return (off >= 0) ? primVals[off] : val;
        }

        public char get(String name, char val) throws IOException {
            int off = getFieldOffset(name, Character.TYPE);
            return (off >= 0) ? Bits.getChar(primVals, off) : val;
        }

        public short get(String name, short val) throws IOException {
            int off = getFieldOffset(name, Short.TYPE);
            return (off >= 0) ? Bits.getShort(primVals, off) : val;
        }

        public int get(String name, int val) throws IOException {
            int off = getFieldOffset(name, Integer.TYPE);
            return (off >= 0) ? Bits.getInt(primVals, off) : val;
        }

        public float get(String name, float val) throws IOException {
            int off = getFieldOffset(name, Float.TYPE);
            return (off >= 0) ? Bits.getFloat(primVals, off) : val;
        }

        public long get(String name, long val) throws IOException {
            int off = getFieldOffset(name, Long.TYPE);
            return (off >= 0) ? Bits.getLong(primVals, off) : val;
        }

        public double get(String name, double val) throws IOException {
            int off = getFieldOffset(name, Double.TYPE);
            return (off >= 0) ? Bits.getDouble(primVals, off) : val;
        }

        public Object get(String name, Object val) throws IOException {
            int off = getFieldOffset(name, Object.class);
            if (off >= 0) {
                int objHandle = objHandles[off];
                handles.markDependency(passHandle, objHandle);
                return (handles.lookupException(objHandle) == null) ?
                    objVals[off] : null;
            } else {
                return val;
            }
        }

        void readFields() throws IOException {
            bin.readFully(primVals, 0, primVals.length, false);

            int oldHandle = passHandle;
            ObjectStreamField[] fields = desc.getFields(false);
            int numPrimFields = fields.length - objVals.length;
            for (int i = 0; i < objVals.length; i++) {
                objVals[i] =
                    readObject0(fields[numPrimFields + i].isUnshared());
                objHandles[i] = passHandle;
            }
            passHandle = oldHandle;
        }

        private int getFieldOffset(String name, Class type) {
            ObjectStreamField field = desc.getField(name, type);
            if (field != null) {
                return field.getOffset();
            } else if (desc.getLocalDesc().getField(name, type) != null) {
                return -1;
            } else {
                throw new IllegalArgumentException("no such field " + name +
                                                   " with type " + type);
            }
        }
    }

    private static class ValidationList {

        private static class Callback {
            final ObjectInputValidation obj;
            final int priority;
            Callback next;
            final AccessControlContext acc;

            Callback(ObjectInputValidation obj, int priority, Callback next,
                AccessControlContext acc)
            {
                this.obj = obj;
                this.priority = priority;
                this.next = next;
                this.acc = acc;
            }
        }

        /** linked list of callbacks */
        private Callback list;

        ValidationList() {
        }

        void register(ObjectInputValidation obj, int priority)
            throws InvalidObjectException
        {
            if (obj == null) {
                throw new InvalidObjectException("null callback");
            }

            Callback prev = null, cur = list;
            while (cur != null && priority < cur.priority) {
                prev = cur;
                cur = cur.next;
            }
            AccessControlContext acc = AccessController.getContext();
            if (prev != null) {
                prev.next = new Callback(obj, priority, cur, acc);
            } else {
                list = new Callback(obj, priority, list, acc);
            }
        }

        void doCallbacks() throws InvalidObjectException {
            try {
                while (list != null) {
                    AccessController.doPrivileged(
                        new PrivilegedExceptionAction()
                    {
                        public Void run() throws InvalidObjectException {
                            list.obj.validateObject();
                            return null;
                        }
                    }, list.acc);
                    list = list.next;
                }
            } catch (PrivilegedActionException ex) {
                list = null;
                throw (InvalidObjectException) ex.getException();
            }
        }

        public void clear() {
            list = null;
        }
    }

    private static class PeekInputStream extends InputStream {

        /** underlying stream */
        private final InputStream in;
        /** peeked byte */
        private int peekb = -1;

        PeekInputStream(InputStream in) {
            this.in = in;
        }

        int peek() throws IOException {
            return (peekb >= 0) ? peekb : (peekb = in.read());
        }

        public int read() throws IOException {
            if (peekb >= 0) {
                int v = peekb;
                peekb = -1;
                return v;
            } else {
                return in.read();
            }
        }

        public int read(byte[] b, int off, int len) throws IOException {
            if (len == 0) {
                return 0;
            } else if (peekb < 0) {
                return in.read(b, off, len);
            } else {
                b[off++] = (byte) peekb;
                len--;
                peekb = -1;
                int n = in.read(b, off, len);
                return (n >= 0) ? (n + 1) : 1;
            }
        }

        void readFully(byte[] b, int off, int len) throws IOException {
            int n = 0;
            while (n < len) {
                int count = read(b, off + n, len - n);
                if (count < 0) {
                    throw new EOFException();
                }
                n += count;
            }
        }

        public long skip(long n) throws IOException {
            if (n <= 0) {
                return 0;
            }
            int skipped = 0;
            if (peekb >= 0) {
                peekb = -1;
                skipped++;
                n--;
            }
            return skipped + skip(n);
        }

        public int available() throws IOException {
            return in.available() + ((peekb >= 0) ? 1 : 0);
        }

        public void close() throws IOException {
            in.close();
        }
    }

    private class BlockDataInputStream
        extends InputStream implements DataInput
    {
        /** maximum data block length */
        private static final int MAX_BLOCK_SIZE = 1024;
        /** maximum data block header length */
        private static final int MAX_HEADER_SIZE = 5;
        /** (tunable) length of char buffer (for reading strings) */
        private static final int CHAR_BUF_SIZE = 256;
        /** readBlockHeader() return value indicating header read may block */
        private static final int HEADER_BLOCKED = -2;

        /** buffer for reading general/block data */
        private final byte[] buf = new byte[MAX_BLOCK_SIZE];
        /** buffer for reading block data headers */
        private final byte[] hbuf = new byte[MAX_HEADER_SIZE];
        /** char buffer for fast string reads */
        private final char[] cbuf = new char[CHAR_BUF_SIZE];

        /** block data mode */
        private boolean blkmode = false;

        // block data state fields; values meaningful only when blkmode true
        /** current offset into buf */
        private int pos = 0;
        /** end offset of valid data in buf, or -1 if no more block data */
        private int end = -1;
        /** number of bytes in current block yet to be read from stream */
        private int unread = 0;

        /** underlying stream (wrapped in peekable filter stream) */
        private final PeekInputStream in;
        /** loopback stream (for data reads that span data blocks) */
        private final DataInputStream din;

        BlockDataInputStream(InputStream in) {
            this.in = new PeekInputStream(in);
            din = new DataInputStream(this);
        }

        boolean setBlockDataMode(boolean newmode) throws IOException {
            if (blkmode == newmode) {
                return blkmode;
            }
            if (newmode) {
                pos = 0;
                end = 0;
                unread = 0;
            } else if (pos < end) {
                throw new IllegalStateException("unread block data");
            }
            blkmode = newmode;
            return !blkmode;
        }

        boolean getBlockDataMode() {
            return blkmode;
        }

        void skipBlockData() throws IOException {
            if (!blkmode) {
                throw new IllegalStateException("not in block data mode");
            }
            while (end >= 0) {
                refill();
            }
        }

        private int readBlockHeader(boolean canBlock) throws IOException {
            if (defaultDataEnd) {
                return -1;
            }
            try {
                for (;;) {
                    int avail = canBlock ? Integer.MAX_VALUE : in.available();
                    if (avail == 0) {
                        return HEADER_BLOCKED;
                    }

                    int tc = in.peek();
                    switch (tc) {
                        case TC_BLOCKDATA:
                            if (avail < 2) {
                                return HEADER_BLOCKED;
                            }
                            in.readFully(hbuf, 0, 2);
                            return hbuf[1] & 0xFF;

                        case TC_BLOCKDATALONG:
                            if (avail < 5) {
                                return HEADER_BLOCKED;
                            }
                            in.readFully(hbuf, 0, 5);
                            int len = Bits.getInt(hbuf, 1);
                            if (len < 0) {
                                throw new StreamCorruptedException(
                                    "illegal block data header length: " +
                                    len);
                            }
                            return len;

                        case TC_RESET:
                            in.read();
                            handleReset();
                            break;

                        default:
                            if (tc >= 0 && (tc < TC_BASE || tc > TC_MAX)) {
                                throw new StreamCorruptedException(
                                    String.format("invalid type code: %02X",
                                    tc));
                            }
                            return -1;
                    }
                }
            } catch (EOFException ex) {
                throw new StreamCorruptedException(
                    "unexpected EOF while reading block data header");
            }
        }

        private void refill() throws IOException {
            try {
                do {
                    pos = 0;
                    if (unread > 0) {
                        int n =
                            in.read(buf, 0, Math.min(unread, MAX_BLOCK_SIZE));
                        if (n >= 0) {
                            end = n;
                            unread -= n;
                        } else {
                            throw new StreamCorruptedException(
                                "unexpected EOF in middle of data block");
                        }
                    } else {
                        int n = readBlockHeader(true);
                        if (n >= 0) {
                            end = 0;
                            unread = n;
                        } else {
                            end = -1;
                            unread = 0;
                        }
                    }
                } while (pos == end);
            } catch (IOException ex) {
                pos = 0;
                end = -1;
                unread = 0;
                throw ex;
            }
        }

        int currentBlockRemaining() {
            if (blkmode) {
                return (end >= 0) ? (end - pos) + unread : 0;
            } else {
                throw new IllegalStateException();
            }
        }

        int peek() throws IOException {
            if (blkmode) {
                if (pos == end) {
                    refill();
                }
                return (end >= 0) ? (buf[pos] & 0xFF) : -1;
            } else {
                return in.peek();
            }
        }

        byte peekByte() throws IOException {
            int val = peek();
            if (val < 0) {
                throw new EOFException();
            }
            return (byte) val;
        }


        /* ----------------- generic input stream methods ------------------ */
        public int read() throws IOException {
            if (blkmode) {
                if (pos == end) {
                    refill();
                }
                return (end >= 0) ? (buf[pos++] & 0xFF) : -1;
            } else {
                return in.read();
            }
        }

        public int read(byte[] b, int off, int len) throws IOException {
            return read(b, off, len, false);
        }

        public long skip(long len) throws IOException {
            long remain = len;
            while (remain > 0) {
                if (blkmode) {
                    if (pos == end) {
                        refill();
                    }
                    if (end < 0) {
                        break;
                    }
                    int nread = (int) Math.min(remain, end - pos);
                    remain -= nread;
                    pos += nread;
                } else {
                    int nread = (int) Math.min(remain, MAX_BLOCK_SIZE);
                    if ((nread = in.read(buf, 0, nread)) < 0) {
                        break;
                    }
                    remain -= nread;
                }
            }
            return len - remain;
        }

        public int available() throws IOException {
            if (blkmode) {
                if ((pos == end) && (unread == 0)) {
                    int n;
                    while ((n = readBlockHeader(false)) == 0) ;
                    switch (n) {
                        case HEADER_BLOCKED:
                            break;

                        case -1:
                            pos = 0;
                            end = -1;
                            break;

                        default:
                            pos = 0;
                            end = 0;
                            unread = n;
                            break;
                    }
                }
                // avoid unnecessary call to in.available() if possible
                int unreadAvail = (unread > 0) ?
                    Math.min(in.available(), unread) : 0;
                return (end >= 0) ? (end - pos) + unreadAvail : 0;
            } else {
                return in.available();
            }
        }

        public void close() throws IOException {
            if (blkmode) {
                pos = 0;
                end = -1;
                unread = 0;
            }
            in.close();
        }

        int read(byte[] b, int off, int len, boolean copy) throws IOException {
            if (len == 0) {
                return 0;
            } else if (blkmode) {
                if (pos == end) {
                    refill();
                }
                if (end < 0) {
                    return -1;
                }
                int nread = Math.min(len, end - pos);
                System.arraycopy(buf, pos, b, off, nread);
                pos += nread;
                return nread;
            } else if (copy) {
                int nread = in.read(buf, 0, Math.min(len, MAX_BLOCK_SIZE));
                if (nread > 0) {
                    System.arraycopy(buf, 0, b, off, nread);
                }
                return nread;
            } else {
                return in.read(b, off, len);
            }
        }

        /* ----------------- primitive data input methods ------------------ */
        public void readFully(byte[] b) throws IOException {
            readFully(b, 0, b.length, false);
        }

        public void readFully(byte[] b, int off, int len) throws IOException {
            readFully(b, off, len, false);
        }

        public void readFully(byte[] b, int off, int len, boolean copy)
            throws IOException
        {
            while (len > 0) {
                int n = read(b, off, len, copy);
                if (n < 0) {
                    throw new EOFException();
                }
                off += n;
                len -= n;
            }
        }

        public int skipBytes(int n) throws IOException {
            return din.skipBytes(n);
        }

        public boolean readBoolean() throws IOException {
            int v = read();
            if (v < 0) {
                throw new EOFException();
            }
            return (v != 0);
        }

        public byte readByte() throws IOException {
            int v = read();
            if (v < 0) {
                throw new EOFException();
            }
            return (byte) v;
        }

        public int readUnsignedByte() throws IOException {
            int v = read();
            if (v < 0) {
                throw new EOFException();
            }
            return v;
        }

        public char readChar() throws IOException {
            if (!blkmode) {
                pos = 0;
                in.readFully(buf, 0, 2);
            } else if (end - pos < 2) {
                return din.readChar();
            }
            char v = Bits.getChar(buf, pos);
            pos += 2;
            return v;
        }

        public short readShort() throws IOException {
            if (!blkmode) {
                pos = 0;
                in.readFully(buf, 0, 2);
            } else if (end - pos < 2) {
                return din.readShort();
            }
            short v = Bits.getShort(buf, pos);
            pos += 2;
            return v;
        }

        public int readUnsignedShort() throws IOException {
            if (!blkmode) {
                pos = 0;
                in.readFully(buf, 0, 2);
            } else if (end - pos < 2) {
                return din.readUnsignedShort();
            }
            int v = Bits.getShort(buf, pos) & 0xFFFF;
            pos += 2;
            return v;
        }

        public int readInt() throws IOException {
            if (!blkmode) {
                pos = 0;
                in.readFully(buf, 0, 4);
            } else if (end - pos < 4) {
                return din.readInt();
            }
            int v = Bits.getInt(buf, pos);
            pos += 4;
            return v;
        }

        public float readFloat() throws IOException {
            if (!blkmode) {
                pos = 0;
                in.readFully(buf, 0, 4);
            } else if (end - pos < 4) {
                return din.readFloat();
            }
            float v = Bits.getFloat(buf, pos);
            pos += 4;
            return v;
        }

        public long readLong() throws IOException {
            if (!blkmode) {
                pos = 0;
                in.readFully(buf, 0, 8);
            } else if (end - pos < 8) {
                return din.readLong();
            }
            long v = Bits.getLong(buf, pos);
            pos += 8;
            return v;
        }

        public double readDouble() throws IOException {
            if (!blkmode) {
                pos = 0;
                in.readFully(buf, 0, 8);
            } else if (end - pos < 8) {
                return din.readDouble();
            }
            double v = Bits.getDouble(buf, pos);
            pos += 8;
            return v;
        }

        public String readUTF() throws IOException {
            return readUTFBody(readUnsignedShort());
        }

        @SuppressWarnings("deprecation")
        public String readLine() throws IOException {
            return din.readLine();      // deprecated, not worth optimizing
        }

        /* -------------- primitive data array input methods --------------- */
        void readBooleans(boolean[] v, int off, int len) throws IOException {
            int stop, endoff = off + len;
            while (off < endoff) {
                if (!blkmode) {
                    int span = Math.min(endoff - off, MAX_BLOCK_SIZE);
                    in.readFully(buf, 0, span);
                    stop = off + span;
                    pos = 0;
                } else if (end - pos < 1) {
                    v[off++] = din.readBoolean();
                    continue;
                } else {
                    stop = Math.min(endoff, off + end - pos);
                }

                while (off < stop) {
                    v[off++] = Bits.getBoolean(buf, pos++);
                }
            }
        }

        void readChars(char[] v, int off, int len) throws IOException {
            int stop, endoff = off + len;
            while (off < endoff) {
                if (!blkmode) {
                    int span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 1);
                    in.readFully(buf, 0, span << 1);
                    stop = off + span;
                    pos = 0;
                } else if (end - pos < 2) {
                    v[off++] = din.readChar();
                    continue;
                } else {
                    stop = Math.min(endoff, off + ((end - pos) >> 1));
                }

                while (off < stop) {
                    v[off++] = Bits.getChar(buf, pos);
                    pos += 2;
                }
            }
        }

        void readShorts(short[] v, int off, int len) throws IOException {
            int stop, endoff = off + len;
            while (off < endoff) {
                if (!blkmode) {
                    int span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 1);
                    in.readFully(buf, 0, span << 1);
                    stop = off + span;
                    pos = 0;
                } else if (end - pos < 2) {
                    v[off++] = din.readShort();
                    continue;
                } else {
                    stop = Math.min(endoff, off + ((end - pos) >> 1));
                }

                while (off < stop) {
                    v[off++] = Bits.getShort(buf, pos);
                    pos += 2;
                }
            }
        }

        void readInts(int[] v, int off, int len) throws IOException {
            int stop, endoff = off + len;
            while (off < endoff) {
                if (!blkmode) {
                    int span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 2);
                    in.readFully(buf, 0, span << 2);
                    stop = off + span;
                    pos = 0;
                } else if (end - pos < 4) {
                    v[off++] = din.readInt();
                    continue;
                } else {
                    stop = Math.min(endoff, off + ((end - pos) >> 2));
                }

                while (off < stop) {
                    v[off++] = Bits.getInt(buf, pos);
                    pos += 4;
                }
            }
        }

        void readFloats(float[] v, int off, int len) throws IOException {
            int span, endoff = off + len;
            while (off < endoff) {
                if (!blkmode) {
                    span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 2);
                    in.readFully(buf, 0, span << 2);
                    pos = 0;
                } else if (end - pos < 4) {
                    v[off++] = din.readFloat();
                    continue;
                } else {
                    span = Math.min(endoff - off, ((end - pos) >> 2));
                }

                bytesToFloats(buf, pos, v, off, span);
                off += span;
                pos += span << 2;
            }
        }

        void readLongs(long[] v, int off, int len) throws IOException {
            int stop, endoff = off + len;
            while (off < endoff) {
                if (!blkmode) {
                    int span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 3);
                    in.readFully(buf, 0, span << 3);
                    stop = off + span;
                    pos = 0;
                } else if (end - pos < 8) {
                    v[off++] = din.readLong();
                    continue;
                } else {
                    stop = Math.min(endoff, off + ((end - pos) >> 3));
                }

                while (off < stop) {
                    v[off++] = Bits.getLong(buf, pos);
                    pos += 8;
                }
            }
        }

        void readDoubles(double[] v, int off, int len) throws IOException {
            int span, endoff = off + len;
            while (off < endoff) {
                if (!blkmode) {
                    span = Math.min(endoff - off, MAX_BLOCK_SIZE >> 3);
                    in.readFully(buf, 0, span << 3);
                    pos = 0;
                } else if (end - pos < 8) {
                    v[off++] = din.readDouble();
                    continue;
                } else {
                    span = Math.min(endoff - off, ((end - pos) >> 3));
                }

                bytesToDoubles(buf, pos, v, off, span);
                off += span;
                pos += span << 3;
            }
        }

        String readLongUTF() throws IOException {
            return readUTFBody(readLong());
        }

        private String readUTFBody(long utflen) throws IOException {
            StringBuilder sbuf = new StringBuilder();
            if (!blkmode) {
                end = pos = 0;
            }

            while (utflen > 0) {
                int avail = end - pos;
                if (avail >= 3 || (long) avail == utflen) {
                    utflen -= readUTFSpan(sbuf, utflen);
                } else {
                    if (blkmode) {
                        // near block boundary, read one byte at a time
                        utflen -= readUTFChar(sbuf, utflen);
                    } else {
                        // shift and refill buffer manually
                        if (avail > 0) {
                            System.arraycopy(buf, pos, buf, 0, avail);
                        }
                        pos = 0;
                        end = (int) Math.min(MAX_BLOCK_SIZE, utflen);
                        in.readFully(buf, avail, end - avail);
                    }
                }
            }

            return sbuf.toString();
        }

        private long readUTFSpan(StringBuilder sbuf, long utflen)
            throws IOException
        {
            int cpos = 0;
            int start = pos;
            int avail = Math.min(end - pos, CHAR_BUF_SIZE);
            // stop short of last char unless all of utf bytes in buffer
            int stop = pos + ((utflen > avail) ? avail - 2 : (int) utflen);
            boolean outOfBounds = false;

            try {
                while (pos < stop) {
                    int b1, b2, b3;
                    b1 = buf[pos++] & 0xFF;
                    switch (b1 >> 4) {
                        case 0:
                        case 1:
                        case 2:
                        case 3:
                        case 4:
                        case 5:
                        case 6:
                        case 7:   // 1 byte format: 0xxxxxxx
                            cbuf[cpos++] = (char) b1;
                            break;

                        case 12:
                        case 13:  // 2 byte format: 110xxxxx 10xxxxxx
                            b2 = buf[pos++];
                            if ((b2 & 0xC0) != 0x80) {
                                throw new UTFDataFormatException();
                            }
                            cbuf[cpos++] = (char) (((b1 & 0x1F) << 6) |
                                                   ((b2 & 0x3F) << 0));
                            break;

                        case 14:  // 3 byte format: 1110xxxx 10xxxxxx 10xxxxxx
                            b3 = buf[pos + 1];
                            b2 = buf[pos + 0];
                            pos += 2;
                            if ((b2 & 0xC0) != 0x80 || (b3 & 0xC0) != 0x80) {
                                throw new UTFDataFormatException();
                            }
                            cbuf[cpos++] = (char) (((b1 & 0x0F) << 12) |
                                                   ((b2 & 0x3F) << 6) |
                                                   ((b3 & 0x3F) << 0));
                            break;

                        default:  // 10xx xxxx, 1111 xxxx
                            throw new UTFDataFormatException();
                    }
                }
            } catch (ArrayIndexOutOfBoundsException ex) {
                outOfBounds = true;
            } finally {
                if (outOfBounds || (pos - start) > utflen) {
                    /*
                     * Fix for 4450867: if a malformed utf char causes the
                     * conversion loop to scan past the expected end of the utf
                     * string, only consume the expected number of utf bytes.
                     */
                    pos = start + (int) utflen;
                    throw new UTFDataFormatException();
                }
            }

            sbuf.append(cbuf, 0, cpos);
            return pos - start;
        }

        private int readUTFChar(StringBuilder sbuf, long utflen)
            throws IOException
        {
            int b1, b2, b3;
            b1 = readByte() & 0xFF;
            switch (b1 >> 4) {
                case 0:
                case 1:
                case 2:
                case 3:
                case 4:
                case 5:
                case 6:
                case 7:     // 1 byte format: 0xxxxxxx
                    sbuf.append((char) b1);
                    return 1;

                case 12:
                case 13:    // 2 byte format: 110xxxxx 10xxxxxx
                    if (utflen < 2) {
                        throw new UTFDataFormatException();
                    }
                    b2 = readByte();
                    if ((b2 & 0xC0) != 0x80) {
                        throw new UTFDataFormatException();
                    }
                    sbuf.append((char) (((b1 & 0x1F) << 6) |
                                        ((b2 & 0x3F) << 0)));
                    return 2;

                case 14:    // 3 byte format: 1110xxxx 10xxxxxx 10xxxxxx
                    if (utflen < 3) {
                        if (utflen == 2) {
                            readByte();         // consume remaining byte
                        }
                        throw new UTFDataFormatException();
                    }
                    b2 = readByte();
                    b3 = readByte();
                    if ((b2 & 0xC0) != 0x80 || (b3 & 0xC0) != 0x80) {
                        throw new UTFDataFormatException();
                    }
                    sbuf.append((char) (((b1 & 0x0F) << 12) |
                                        ((b2 & 0x3F) << 6) |
                                        ((b3 & 0x3F) << 0)));
                    return 3;

                default:   // 10xx xxxx, 1111 xxxx
                    throw new UTFDataFormatException();
            }
        }
    }

    // REMIND: add full description of exception propagation algorithm?
    private static class HandleTable {

        /* status codes indicating whether object has associated exception */
        private static final byte STATUS_OK = 1;
        private static final byte STATUS_UNKNOWN = 2;
        private static final byte STATUS_EXCEPTION = 3;

        /** array mapping handle -> object status */
        byte[] status;
        /** array mapping handle -> object/exception (depending on status) */
        Object[] entries;
        /** array mapping handle -> list of dependent handles (if any) */
        HandleList[] deps;
        /** lowest unresolved dependency */
        int lowDep = -1;
        /** number of handles in table */
        int size = 0;

        HandleTable(int initialCapacity) {
            status = new byte[initialCapacity];
            entries = new Object[initialCapacity];
            deps = new HandleList[initialCapacity];
        }

        int assign(Object obj) {
            if (size >= entries.length) {
                grow();
            }
            status[size] = STATUS_UNKNOWN;
            entries[size] = obj;
            return size++;
        }

        void markDependency(int dependent, int target) {
            if (dependent == NULL_HANDLE || target == NULL_HANDLE) {
                return;
            }
            switch (status[dependent]) {

                case STATUS_UNKNOWN:
                    switch (status[target]) {
                        case STATUS_OK:
                            // ignore dependencies on objs with no exception
                            break;

                        case STATUS_EXCEPTION:
                            // eagerly propagate exception
                            markException(dependent,
                                (ClassNotFoundException) entries[target]);
                            break;

                        case STATUS_UNKNOWN:
                            // add to dependency list of target
                            if (deps[target] == null) {
                                deps[target] = new HandleList();
                            }
                            deps[target].add(dependent);

                            // remember lowest unresolved target seen
                            if (lowDep < 0 || lowDep > target) {
                                lowDep = target;
                            }
                            break;

                        default:
                            throw new InternalError();
                    }
                    break;

                case STATUS_EXCEPTION:
                    break;

                default:
                    throw new InternalError();
            }
        }

        void markException(int handle, ClassNotFoundException ex) {
            switch (status[handle]) {
                case STATUS_UNKNOWN:
                    status[handle] = STATUS_EXCEPTION;
                    entries[handle] = ex;

                    // propagate exception to dependents
                    HandleList dlist = deps[handle];
                    if (dlist != null) {
                        int ndeps = dlist.size();
                        for (int i = 0; i < ndeps; i++) {
                            markException(dlist.get(i), ex);
                        }
                        deps[handle] = null;
                    }
                    break;

                case STATUS_EXCEPTION:
                    break;

                default:
                    throw new InternalError();
            }
        }

        void finish(int handle) {
            int end;
            if (lowDep < 0) {
                // no pending unknowns, only resolve current handle
                end = handle + 1;
            } else if (lowDep >= handle) {
                // pending unknowns now clearable, resolve all upward handles
                end = size;
                lowDep = -1;
            } else {
                // unresolved backrefs present, can't resolve anything yet
                return;
            }

            // change STATUS_UNKNOWN -> STATUS_OK in selected span of handles
            for (int i = handle; i < end; i++) {
                switch (status[i]) {
                    case STATUS_UNKNOWN:
                        status[i] = STATUS_OK;
                        deps[i] = null;
                        break;

                    case STATUS_OK:
                    case STATUS_EXCEPTION:
                        break;

                    default:
                        throw new InternalError();
                }
            }
        }

        void setObject(int handle, Object obj) {
            switch (status[handle]) {
                case STATUS_UNKNOWN:
                case STATUS_OK:
                    entries[handle] = obj;
                    break;

                case STATUS_EXCEPTION:
                    break;

                default:
                    throw new InternalError();
            }
        }

        Object lookupObject(int handle) {
            return (handle != NULL_HANDLE &&
                    status[handle] != STATUS_EXCEPTION) ?
                entries[handle] : null;
        }

        ClassNotFoundException lookupException(int handle) {
            return (handle != NULL_HANDLE &&
                    status[handle] == STATUS_EXCEPTION) ?
                (ClassNotFoundException) entries[handle] : null;
        }

        void clear() {
            Arrays.fill(status, 0, size, (byte) 0);
            Arrays.fill(entries, 0, size, null);
            Arrays.fill(deps, 0, size, null);
            lowDep = -1;
            size = 0;
        }

        int size() {
            return size;
        }

        private void grow() {
            int newCapacity = (entries.length << 1) + 1;

            byte[] newStatus = new byte[newCapacity];
            Object[] newEntries = new Object[newCapacity];
            HandleList[] newDeps = new HandleList[newCapacity];

            System.arraycopy(status, 0, newStatus, 0, size);
            System.arraycopy(entries, 0, newEntries, 0, size);
            System.arraycopy(deps, 0, newDeps, 0, size);

            status = newStatus;
            entries = newEntries;
            deps = newDeps;
        }

        private static class HandleList {
            private int[] list = new int[4];
            private int size = 0;

            public HandleList() {
            }

            public void add(int handle) {
                if (size >= list.length) {
                    int[] newList = new int[list.length << 1];
                    System.arraycopy(list, 0, newList, 0, list.length);
                    list = newList;
                }
                list[size++] = handle;
            }

            public int get(int index) {
                if (index >= size) {
                    throw new ArrayIndexOutOfBoundsException();
                }
                return list[index];
            }

            public int size() {
                return size;
            }
        }
    }

    private static Object cloneArray(Object array) {
        if (array instanceof Object[]) {
            return ((Object[]) array).clone();
        } else if (array instanceof boolean[]) {
            return ((boolean[]) array).clone();
        } else if (array instanceof byte[]) {
            return ((byte[]) array).clone();
        } else if (array instanceof char[]) {
            return ((char[]) array).clone();
        } else if (array instanceof double[]) {
            return ((double[]) array).clone();
        } else if (array instanceof float[]) {
            return ((float[]) array).clone();
        } else if (array instanceof int[]) {
            return ((int[]) array).clone();
        } else if (array instanceof long[]) {
            return ((long[]) array).clone();
        } else if (array instanceof short[]) {
            return ((short[]) array).clone();
        } else {
            throw new AssertionError();
        }
    }

    private void validateDescriptor(ObjectStreamClass descriptor) {
        ObjectStreamClassValidator validating = validator;
        if (validating != null) {
            validating.validateDescriptor(descriptor);
        }
    }

    // controlled access to ObjectStreamClassValidator
    private volatile ObjectStreamClassValidator validator;

    private static void setValidator(ObjectInputStream ois, ObjectStreamClassValidator validator) {
        ois.validator = validator;
    }
    static {
        SharedSecrets.setJavaObjectInputStreamAccess(ObjectInputStream::setValidator);
    }
}