一、前言
源码解析Zookeeper的细节，首先从序列化入手，因为在网络通信、数据存储中都用到了序列化。
二、序列化
序列化主要在zookeeper.jute包中，其中涉及的主要接口如下
· InputArchive
· OutputArchive
· Index
· Record
2.1 InputArchive
/**
* 所有的反序列化必须实现的接口
* Interface that all the Deserializers have to implement.
*
*/
public interface InputArchive {
// 读取byte类型
public byte readByte(String tag) throws IOException;
// 读取boolean类型
public boolean readBool(String tag) throws IOException;
public int readInt(String tag) throws IOException;
public long readLong(String tag) throws IOException;
public float readFloat(String tag) throws IOException;
public double readDouble(String tag) throws IOException;
public String readString(String tag) throws IOException;
public byte[] readBuffer(String tag) throws IOException;
public void readRecord(Record r, String tag) throws IOException;
public void startRecord(String tag) throws IOException;
public void endRecord(String tag) throws IOException;
public Index startVector(String tag) throws IOException;
public void endVector(String tag) throws IOException;
// 开始读取Map
public Index startMap(String tag) throws IOException;
// 结束读取Map
public void endMap(String tag) throws IOException;
}
具体实现类有三个
image.png
2.2 OutputArchive
其是所有序列化器都需要实现此接口，其方法如下。
/**
* Interface that alll the serializers have to implement.
*
*/
public interface OutputArchive {
public void writeByte(byte b, String tag) throws IOException;
public void writeBool(boolean b, String tag) throws IOException;
public void writeInt(int i, String tag) throws IOException;
public void writeLong(long l, String tag) throws IOException;
public void writeFloat(float f, String tag) throws IOException;
public void writeDouble(double d, String tag) throws IOException;
public void writeString(String s, String tag) throws IOException;
public void writeBuffer(byte buf[], String tag)
throws IOException;
public void writeRecord(Record r, String tag) throws IOException;
public void startRecord(Record r, String tag) throws IOException;
public void endRecord(Record r, String tag) throws IOException;
public void startVector(List v, String tag) throws IOException;
public void endVector(List v, String tag) throws IOException;
public void startMap(TreeMap v, String tag) throws IOException;
public void endMap(TreeMap v, String tag) throws IOException;
}
实现类：
image.png
2.3 Index
其用于迭代反序列化器的迭代器。
/**
* Interface that acts as an iterator for deserializing maps.
* The deserializer returns an instance that the record uses to
* read vectors and maps. An example of usage is as follows:
*
*
* Index idx = startVector(...);
* while (!idx.done()) {
* .... // read element of a vector
* idx.incr();
* }
*
*
*/
public interface Index {
public boolean done();
public void incr();
}
子类：
image.png
2.4 Record
所有用于网络传输或者本地存储的类型都实现该接口，其方法如下
/**
* Interface that is implemented by generated classes.
*
*/
@InterfaceAudience.Public
public interface Record {
public void serialize(OutputArchive archive, String tag)
throws IOException;
public void deserialize(InputArchive archive, String tag)
throws IOException;
}
所有的实现类都需要实现seriallize和deserialize方法。
example:
public class ArchiveTest {
public static void main(String[] args) throws IOException {
//存储文件路径
String path = "D:\\test.txt";
// write operation
OutputStream outputStream = new FileOutputStream(new File(path));
BinaryOutputArchive binaryOutputArchive = BinaryOutputArchive.getArchive(outputStream);
binaryOutputArchive.writeBool(true, "boolean");
byte[] bytes = "leesf".getBytes();
binaryOutputArchive.writeBuffer(bytes, "buffer");
binaryOutputArchive.writeDouble(13.14, "double");
binaryOutputArchive.writeFloat(5.20f, "float");
binaryOutputArchive.writeInt(520, "int");
Person person = new Person(25, "leesf");
binaryOutputArchive.writeRecord(person, "leesf");
TreeMap map = new TreeMap();
map.put("leesf", 25);
map.put("dyd", 25);
Set keys = map.keySet();
binaryOutputArchive.startMap(map, "map");
int i = 0;
for (String key: keys) {
String tag = i + "";
binaryOutputArchive.writeString(key, tag);
binaryOutputArchive.writeInt(map.get(key), tag);
i++;
}
binaryOutputArchive.endMap(map, "map");
//read operation
InputStream inputStream = new FileInputStream(new File(path));
BinaryInputArchive binaryInputArchive = BinaryInputArchive.getArchive(inputStream);
System.out.println(binaryInputArchive.readBool("boolean"));
System.out.println(new String(binaryInputArchive.readBuffer("buffer")));
System.out.println(binaryInputArchive.readDouble("double"));
System.out.println(binaryInputArchive.readFloat("float"));
System.out.println(binaryInputArchive.readInt("int"));
Person person2 = new Person();
binaryInputArchive.readRecord(person2, "leesf");
System.out.println(person2);
Index index = binaryInputArchive.startMap("map");
int j = 0;
while (!index.done()) {
String tag = j + "";
System.out.println("key = " + binaryInputArchive.readString(tag)
+ ", value = " + binaryInputArchive.readInt(tag));
index.incr();
j++;
}
}
/**
* 必须实现序列化和反序列化接口
*/
static class Person implements Record {
private int age;
private String name;
public Person() {
}
public Person(int age, String name) {
this.age = age;
this.name = name;
}
public void serialize(OutputArchive archive, String tag) throws IOException {
archive.startRecord(this, tag);
archive.writeInt(age, "age");
archive.writeString(name, "name");
archive.endRecord(this, tag);
}
public void deserialize(InputArchive archive, String tag) throws IOException {
archive.startRecord(tag);
age = archive.readInt("age");
name = archive.readString("name");
archive.endRecord(tag);
}
public String toString() {
return "age = " + age + ", name = " + name;
}
}
}
写操作以后文件中内容：
image.png
执行结果：
image.png