先通过demo演示效果，然后进行源码分析
demo用Enhancer结合MethodInterceptor以及CallBackFilter完成
这里Enhancer类是CGLib中的一个字节码增强器，它可以方便的对你想要处理的类进行扩展
1.demo
拦截器1
package cglib;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
import java.lang.reflect.Method;
public class CglibProxy implements MethodInterceptor {
//实现MethodInterceptor接口，定义方法的拦截器
@Override
public Object intercept(Object o, Method method, Object[] objects,
MethodProxy methodProxy) throws Throwable {
System.out.println("pre");
//通过代理类调用父类中的方法,即实体类方法
Object result = methodProxy.invokeSuper(o, objects);
System.out.println("after");
return result;
}
}
拦截器2
package cglib;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
import java.lang.reflect.Method;
public class CglibProxy2 implements MethodInterceptor {
//实现MethodInterceptor接口，定义方法的拦截器
@Override
public Object intercept(Object o, Method method, Object[] objects,
MethodProxy methodProxy) throws Throwable {
System.out.println("pre1");
//通过代理类调用父类中的方法,即实体类方法
Object result = methodProxy.invokeSuper(o, objects);
System.out.println("after1");
return result;
}
}
回调过滤器CallbackFilter
package cglib;
import net.sf.cglib.proxy.CallbackFilter;
import java.lang.reflect.Method;
public class filter implements CallbackFilter {
@Override
public int accept(Method method) {
if(method.getName().equals("toString")) {
return 1;
}
return 0;
}
}
测试类
package cglib;
import net.sf.cglib.core.DebuggingClassWriter;
import net.sf.cglib.proxy.Callback;
import net.sf.cglib.proxy.Enhancer;
public class CglibLearn {
//定义委托类，可以不是接口
static class serviceImpl {
void say()
{
System.out.println("say");
}
}
public static Object getProxyInstance(Object realSubject) {
Enhancer enhancer = new Enhancer();
//需要创建子类的类,即定义委托类
enhancer.setSuperclass(realSubject.getClass());
//设置两个CallBack以及CallbackFilter
Callback[] callbacks=new Callback[2];
callbacks[0]=new CglibProxy();
callbacks[1]=new CglibProxy2();
enhancer.setCallbacks(callbacks);
enhancer.setCallbackFilter(new filter());
//通过字节码技术动态创建子类实例
return enhancer.create();
}
public static void main(String[] args) {
//将sam,class文件写到硬盘
System.setProperty(DebuggingClassWriter.DEBUG_LOCATION_PROPERTY, ".//");
//通过生成子类的方式创建代理类
serviceImpl impl = (serviceImpl)getProxyInstance(new serviceImpl());
impl.say();
impl.toString();
}
}
输出,自己想想就知道
2.源码分析
看源码之前，最好先了解下callBack和callBackFilter是有什么作用，再看会带着问题看
直接进测试类的enhancer.create();探究这个代理对象是怎么生成的,下面按照几个注意的环节来讲，会经历整个创建过程
2.1根据代理类的配置作为组合Key
net.sf.cglib.proxy.Enhancer#create()
net.sf.cglib.proxy.Enhancer#createHelper()
private Object createHelper() {
//进行有效性验证，比如有多个callBack却没有callBackFilter
validate();
if (superclass != null) {
setNamePrefix(superclass.getName());
} else if (interfaces != null) {
setNamePrefix(interfaces[ReflectUtils.findPackageProtected(interfaces)].getName());
}
//先根据KEY_FACTORY 以当前代理类的配置信息 生成一个组合Key，再利用这个组合Key，进行create
return super.create(KEY_FACTORY.newInstance((superclass != null) ? superclass.getName() : null,
ReflectUtils.getNames(interfaces),
filter,
callbackTypes,
useFactory,
interceptDuringConstruction,
serialVersionUID));
}
这里注意
KEY_FACTORY 就是前两节讲到的根据KeyFactory，完成multi-value的一个Key
可以理解成这里如果代理类的配置，作为Key，一样的换就能利用缓存了，后面会讲到利用的缓存
private static final EnhancerKey KEY_FACTORY =
(EnhancerKey)KeyFactory.create(EnhancerKey.class);
public interface EnhancerKey {
public Object newInstance(String type,
String[] interfaces,
CallbackFilter filter,
Type[] callbackTypes,
boolean useFactory,
boolean interceptDuringConstruction,
Long serialVersionUID);
}
2.2 利用缓存完成根据Key获取Class信息，进而生成代理对象
这一块代码比较简单，和之前jdk动态代理利用的缓存差不多,在KeyFactory那一节也讲过，还是列出来就行,看注释就够了
protected Object create(Object key) {
try {
//需要缓存的类
Class gen = null;
synchronized (source) {
ClassLoader loader = getClassLoader();
Map cache2 = null;
//根据来源区分,根据classLoader进行一级缓存
cache2 = (Map)source.cache.get(loader);
if (cache2 == null) {
cache2 = new HashMap();
cache2.put(NAME_KEY, new HashSet());
source.cache.put(loader, cache2);
} else if (useCache) {
//用缓存
Reference ref = (Reference)cache2.get(key);
gen = (Class) (( ref == null ) ? null : ref.get());
}
if (gen == null) {
Object save = CURRENT.get();
CURRENT.set(this);
try {
this.key = key;
if (attemptLoad) {
try {
gen = loader.loadClass(getClassName());
} catch (ClassNotFoundException e) {
// ignore
}
}
if (gen == null) {
//结合生成策略，得到类的字节码
byte[] b = strategy.generate(this);
String className = ClassNameReader.getClassName(new ClassReader(b));
getClassNameCache(loader).add(className);
//根据字节码生成类
gen = ReflectUtils.defineClass(className, b, loader);
}
if (useCache) {
//根据传入的key，进行二级缓存
cache2.put(key, new WeakReference(gen));
}
//根据类，生成实例
return firstInstance(gen);
} finally {
CURRENT.set(save);
}
}
}
return firstInstance(gen);
} catch (RuntimeException e) {
throw e;
} catch (Error e) {
throw e;
} catch (Exception e) {
throw new CodeGenerationException(e);
}
}
可以看出来，关注点集中在代理类的生成,即
byte[] b = strategy.generate(this);
2.3.代理类的生成
继续跟进
net.sf.cglib.core.GeneratorStrategy#generate
net.sf.cglib.core.DefaultGeneratorStrategy#generate
net.sf.cglib.core.ClassGenerator#generateClass
net.sf.cglib.proxy.Enhancer#generateClass
最终就是利用Enhancer来生成代理类,下面有详细的注释
public void generateClass(ClassVisitor v) throws Exception {
Class sc = (superclass == null) ? Object.class : superclass;
if (TypeUtils.isFinal(sc.getModifiers()))
throw new IllegalArgumentException("Cannot subclass final class " + sc);
List constructors = new ArrayList(Arrays.asList(sc.getDeclaredConstructors()));
filterConstructors(sc, constructors);
// Order is very important: must add superclass, then
// its superclass chain, then each interface and
// its superinterfaces.
List actualMethods = new ArrayList();
List interfaceMethods = new ArrayList();
final Set forcePublic = new HashSet();
/*
根据规定的父类，生成需要的方法，参见 CglibLearn$serviceImpl$$EnhancerByCGLIB$$81852b18.class
actualMethods记录所有经过过滤的方法
interfaceMethods和forcePublic的size都为0
*/
getMethods(sc, interfaces, actualMethods, interfaceMethods, forcePublic);
for(int i=0;i备注，上面利用asm完成类的生成,主要步骤如下
1.getMethods(sc, interfaces, actualMethods, interfaceMethods, forcePublic);
这个方法就是递归的将superClass的父类，父接口的函数全部记录在method中,
然后过滤掉原有类的static方法，private方法,和superClass位于不同包的类中的方法(不知道何时会出现这种情况???),以及final方法
获取，并且过滤完之后，剩下的方法是
void cglib.CglibLearn$serviceImpl.say()
protected void java.lang.Object.finalize() throws java.lang.Throwable
public boolean java.lang.Object.equals(java.lang.Object)
public java.lang.String java.lang.Object.toString()
public native int java.lang.Object.hashCode()
protected native java.lang.Object java.lang.Object.clone() throws java.lang.CloneNotSupportedException
2.emitMethods
这个函数是用来生成代理类里面的methods，非常重要，列出源码如下
/*
methods 是方法的信息列表, 每一个类型都是MethodInfo
actualMethods 是真实的方法, 每一个类型都是Method
*/
private void emitMethods(final ClassEmitter ce, List methods, List actualMethods) {
/*
根据callbackTypes得到对应的generator,跟进去看
比如callbackType是MethodInterceptor.class,对应的generator就是MethodInterceptorGenerator.INSTANCE
*/
CallbackGenerator[] generators = CallbackInfo.getGenerators(callbackTypes);
Map groups = new HashMap();
final Map indexes = new HashMap();
final Map originalModifiers = new HashMap();
final Map positions = CollectionUtils.getIndexMap(methods);
final Map declToBridge = new HashMap();
Iterator it1 = methods.iterator();
Iterator it2 = (actualMethods != null) ? actualMethods.iterator() : null;
while (it1.hasNext()) {
MethodInfo method = (MethodInfo)it1.next();
Method actualMethod = (it2 != null) ? (Method)it2.next() : null;
/*
根据定义的callBackFilter的accept值，判断由哪一个callBack来过滤当前方法
filter这里默认是net.sf.cglib.proxy.Enhancer.ALL_ZERO,即accept永远返回0
*/
int index = filter.accept(actualMethod);
if (index >= callbackTypes.length) {
throw new IllegalArgumentException("Callback filter returned an index that is too large: " + index);
}
originalModifiers.put(method, new Integer((actualMethod != null) ? actualMethod.getModifiers() : method.getModifiers()));
//通过indexes这个map记录每个map该由第几个callBack来处理
indexes.put(method, new Integer(index));
//让这个callBack对应的generator 记录下来它要处理这个method
List group = (List)groups.get(generators[index]);
if (group == null) {
groups.put(generators[index], group = new ArrayList(methods.size()));
}
group.add(method);
// Optimization: build up a map of Class -> bridge methods in class
// so that we can look up all the bridge methods in one pass for a class.
if (TypeUtils.isBridge(actualMethod.getModifiers())) {
Set bridges = (Set)declToBridge.get(actualMethod.getDeclaringClass());
if (bridges == null) {
bridges = new HashSet();
declToBridge.put(actualMethod.getDeclaringClass(), bridges);
}
bridges.add(method.getSignature());
}
}
final Map bridgeToTarget = new BridgeMethodResolver(declToBridge).resolveAll();
Set seenGen = new HashSet();
CodeEmitter se = ce.getStaticHook();
se.new_instance(THREAD_LOCAL);
se.dup();
se.invoke_constructor(THREAD_LOCAL, CSTRUCT_NULL);
se.putfield(THREAD_CALLBACKS_FIELD);
final Object[] state = new Object[1];
//下面context定义了如何根据callBack信息，来进行代码生成
CallbackGenerator.Context context = new CallbackGenerator.Context() {
public ClassLoader getClassLoader() {
return Enhancer.this.getClassLoader();
}
public int getOriginalModifiers(MethodInfo method) {
return ((Integer)originalModifiers.get(method)).intValue();
}
//根据method判断对应的callBack下标
public int getIndex(MethodInfo method) {
return ((Integer)indexes.get(method)).intValue();
}
/*
根据下标让当前method生成“调用对应callBack”的代码
这也表现出来一个method只有一个callBack
*/
public void emitCallback(CodeEmitter e, int index) {
emitCurrentCallback(e, index);
}
public Signature getImplSignature(MethodInfo method) {
return rename(method.getSignature(), ((Integer)positions.get(method)).intValue());
}
public void emitInvoke(CodeEmitter e, MethodInfo method) {
// If this is a bridge and we know the target was called from invokespecial,
// then we need to invoke_virtual w/ the bridge target instead of doing
// a super, because super may itself be using super, which would bypass
// any proxies on the target.
Signature bridgeTarget = (Signature)bridgeToTarget.get(method.getSignature());
if (bridgeTarget != null) {
// TODO: this assumes that the target has wider or the same type
// parameters than the current.
// In reality this should always be true because otherwise we wouldn't
// have had a bridge doing an invokespecial.
// If it isn't true, we would need to checkcast each argument
// against the target's argument types
e.invoke_virtual_this(bridgeTarget);
Type retType = method.getSignature().getReturnType();
// Not necessary to cast if the target & bridge have
// the same return type.
// (This conveniently includes void and primitive types,
// which would fail if casted. It's not possible to
// covariant from boxed to unbox (or vice versa), so no having
// to box/unbox for bridges).
// TODO: It also isn't necessary to checkcast if the return is
// assignable from the target. (This would happen if a subclass
// used covariant returns to narrow the return type within a bridge
// method.)
if (!retType.equals(bridgeTarget.getReturnType())) {
e.checkcast(retType);
}
} else {
e.super_invoke(method.getSignature());
}
}
public CodeEmitter beginMethod(ClassEmitter ce, MethodInfo method) {
CodeEmitter e = EmitUtils.begin_method(ce, method);
if (!interceptDuringConstruction &&
!TypeUtils.isAbstract(method.getModifiers())) {
Label constructed = e.make_label();
e.load_this();
e.getfield(CONSTRUCTED_FIELD);
e.if_jump(e.NE, constructed);
e.load_this();
e.load_args();
e.super_invoke();
e.return_value();
e.mark(constructed);
}
return e;
}
};
for (int i = 0; i < callbackTypes.length; i++) {
CallbackGenerator gen = generators[i];
if (!seenGen.contains(gen)) {
seenGen.add(gen);
/*
每个callBack对应的generator要处理的列表为fmethods
下面将每个method对应的callBack调用关系，生成代码
*/
final List fmethods = (List)groups.get(gen);
if (fmethods != null) {
try {
gen.generate(ce, context, fmethods);
gen.generateStatic(se, context, fmethods);
} catch (RuntimeException x) {
throw x;
} catch (Exception x) {
throw new CodeGenerationException(x);
}
}
}
}
se.return_value();
se.end_method();
}
这里的主要工作如下
int index = filter.accept(actualMethod); 这里是判断当前method是由哪一个callBack来处理
...
定义如何根据callBack信息，来进行代码生成
CallbackGenerator.Context context = new CallbackGenerator.Context(){xxx}
...
每个callBack对应的generator要处理的列表为fmethods
下面将每个method对应的callBack调用关系，生成代码
final List fmethods = (List)groups.get(gen);
2.4.代理类的结果
本地生成了文件
image.png
其中，CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b文件的细节在intellij并没有显示完全，用
http://www.javadecompilers.com/result 去decompile一下，可以看到细节,一定要展示出来，方便理解代理类创建的过程
/*
* Decompiled with CFR 0_118.
*
* Could not load the following classes:
* cglib.CglibLearn
* cglib.CglibLearn$serviceImpl
* net.sf.cglib.core.ReflectUtils
* net.sf.cglib.core.Signature
* net.sf.cglib.proxy.Callback
* net.sf.cglib.proxy.Factory
* net.sf.cglib.proxy.MethodInterceptor
* net.sf.cglib.proxy.MethodProxy
*/
package cglib;
import cglib.CglibLearn;
import java.lang.reflect.Method;
import net.sf.cglib.core.ReflectUtils;
import net.sf.cglib.core.Signature;
import net.sf.cglib.proxy.Callback;
import net.sf.cglib.proxy.Factory;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
public class CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b
extends CglibLearn.serviceImpl
implements Factory {
private boolean CGLIB$BOUND;
private static final ThreadLocal CGLIB$THREAD_CALLBACKS;
private static final Callback[] CGLIB$STATIC_CALLBACKS;
private MethodInterceptor CGLIB$CALLBACK_0;
private MethodInterceptor CGLIB$CALLBACK_1;
private static final Method CGLIB$say$0$Method;
private static final MethodProxy CGLIB$say$0$Proxy;
private static final Object[] CGLIB$emptyArgs;
private static final Method CGLIB$finalize$1$Method;
private static final MethodProxy CGLIB$finalize$1$Proxy;
private static final Method CGLIB$equals$2$Method;
private static final MethodProxy CGLIB$equals$2$Proxy;
private static final Method CGLIB$toString$3$Method;
private static final MethodProxy CGLIB$toString$3$Proxy;
private static final Method CGLIB$hashCode$4$Method;
private static final MethodProxy CGLIB$hashCode$4$Proxy;
private static final Method CGLIB$clone$5$Method;
private static final MethodProxy CGLIB$clone$5$Proxy;
static void CGLIB$STATICHOOK1() {
CGLIB$THREAD_CALLBACKS = new ThreadLocal();
CGLIB$emptyArgs = new Object[0];
Class class_ = Class.forName("cglib.CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b");
Class class_2 = Class.forName("java.lang.Object");
Method[] arrmethod = ReflectUtils.findMethods((String[])new String[]{"finalize", "()V", "equals", "(Ljava/lang/Object;)Z", "toString", "()Ljava/lang/String;", "hashCode", "()I", "clone", "()Ljava/lang/Object;"}, (Method[])class_2.getDeclaredMethods());
CGLIB$finalize$1$Method = arrmethod[0];
CGLIB$finalize$1$Proxy = MethodProxy.create(class_2, class_, (String)"()V", (String)"finalize", (String)"CGLIB$finalize$1");
CGLIB$equals$2$Method = arrmethod[1];
CGLIB$equals$2$Proxy = MethodProxy.create(class_2, class_, (String)"(Ljava/lang/Object;)Z", (String)"equals", (String)"CGLIB$equals$2");
CGLIB$toString$3$Method = arrmethod[2];
CGLIB$toString$3$Proxy = MethodProxy.create(class_2, class_, (String)"()Ljava/lang/String;", (String)"toString", (String)"CGLIB$toString$3");
CGLIB$hashCode$4$Method = arrmethod[3];
CGLIB$hashCode$4$Proxy = MethodProxy.create(class_2, class_, (String)"()I", (String)"hashCode", (String)"CGLIB$hashCode$4");
CGLIB$clone$5$Method = arrmethod[4];
CGLIB$clone$5$Proxy = MethodProxy.create(class_2, class_, (String)"()Ljava/lang/Object;", (String)"clone", (String)"CGLIB$clone$5");
class_2 = Class.forName("cglib.CglibLearn$serviceImpl");
CGLIB$say$0$Method = ReflectUtils.findMethods((String[])new String[]{"say", "()V"}, (Method[])class_2.getDeclaredMethods())[0];
CGLIB$say$0$Proxy = MethodProxy.create(class_2, class_, (String)"()V", (String)"say", (String)"CGLIB$say$0");
}
final void CGLIB$say$0() {
super.say();
}
final void say() {
MethodInterceptor methodInterceptor = this.CGLIB$CALLBACK_0;
if (methodInterceptor == null) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)this);
methodInterceptor = this.CGLIB$CALLBACK_0;
}
if (methodInterceptor != null) {
Object object = methodInterceptor.intercept((Object)this, CGLIB$say$0$Method, CGLIB$emptyArgs, CGLIB$say$0$Proxy);
return;
}
super.say();
}
final void CGLIB$finalize$1() throws Throwable {
super.finalize();
}
protected final void finalize() throws Throwable {
MethodInterceptor methodInterceptor = this.CGLIB$CALLBACK_0;
if (methodInterceptor == null) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)this);
methodInterceptor = this.CGLIB$CALLBACK_0;
}
if (methodInterceptor != null) {
Object object = methodInterceptor.intercept((Object)this, CGLIB$finalize$1$Method, CGLIB$emptyArgs, CGLIB$finalize$1$Proxy);
return;
}
super.finalize();
}
final boolean CGLIB$equals$2(Object object) {
return super.equals(object);
}
public final boolean equals(Object object) {
MethodInterceptor methodInterceptor = this.CGLIB$CALLBACK_0;
if (methodInterceptor == null) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)this);
methodInterceptor = this.CGLIB$CALLBACK_0;
}
if (methodInterceptor != null) {
Object object2 = methodInterceptor.intercept((Object)this, CGLIB$equals$2$Method, new Object[]{object}, CGLIB$equals$2$Proxy);
return object2 == null ? false : (Boolean)object2;
}
return super.equals(object);
}
final String CGLIB$toString$3() {
return super.toString();
}
public final String toString() {
MethodInterceptor methodInterceptor = this.CGLIB$CALLBACK_1;
if (methodInterceptor == null) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)this);
methodInterceptor = this.CGLIB$CALLBACK_1;
}
if (methodInterceptor != null) {
return (String)methodInterceptor.intercept((Object)this, CGLIB$toString$3$Method, CGLIB$emptyArgs, CGLIB$toString$3$Proxy);
}
return super.toString();
}
final int CGLIB$hashCode$4() {
return super.hashCode();
}
public final int hashCode() {
MethodInterceptor methodInterceptor = this.CGLIB$CALLBACK_0;
if (methodInterceptor == null) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)this);
methodInterceptor = this.CGLIB$CALLBACK_0;
}
if (methodInterceptor != null) {
Object object = methodInterceptor.intercept((Object)this, CGLIB$hashCode$4$Method, CGLIB$emptyArgs, CGLIB$hashCode$4$Proxy);
return object == null ? 0 : ((Number)object).intValue();
}
return super.hashCode();
}
final Object CGLIB$clone$5() throws CloneNotSupportedException {
return super.clone();
}
protected final Object clone() throws CloneNotSupportedException {
MethodInterceptor methodInterceptor = this.CGLIB$CALLBACK_0;
if (methodInterceptor == null) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)this);
methodInterceptor = this.CGLIB$CALLBACK_0;
}
if (methodInterceptor != null) {
return methodInterceptor.intercept((Object)this, CGLIB$clone$5$Method, CGLIB$emptyArgs, CGLIB$clone$5$Proxy);
}
return super.clone();
}
public static MethodProxy CGLIB$findMethodProxy(Signature signature) {
String string = signature.toString();
switch (string.hashCode()) {
case -1574182249: {
if (!string.equals("finalize()V")) break;
return CGLIB$finalize$1$Proxy;
}
case -909388886: {
if (!string.equals("say()V")) break;
return CGLIB$say$0$Proxy;
}
case -508378822: {
if (!string.equals("clone()Ljava/lang/Object;")) break;
return CGLIB$clone$5$Proxy;
}
case 1826985398: {
if (!string.equals("equals(Ljava/lang/Object;)Z")) break;
return CGLIB$equals$2$Proxy;
}
case 1913648695: {
if (!string.equals("toString()Ljava/lang/String;")) break;
return CGLIB$toString$3$Proxy;
}
case 1984935277: {
if (!string.equals("hashCode()I")) break;
return CGLIB$hashCode$4$Proxy;
}
}
return null;
}
public CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b() {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b = this;
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b);
}
public static void CGLIB$SET_THREAD_CALLBACKS(Callback[] arrcallback) {
CGLIB$THREAD_CALLBACKS.set(arrcallback);
}
public static void CGLIB$SET_STATIC_CALLBACKS(Callback[] arrcallback) {
CGLIB$STATIC_CALLBACKS = arrcallback;
}
private static final void CGLIB$BIND_CALLBACKS(Object object) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b = (CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b)((Object)object);
if (!cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BOUND) {
cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BOUND = true;
Object t = CGLIB$THREAD_CALLBACKS.get();
if (t != null || (v312 = CGLIB$STATIC_CALLBACKS) != null) {
Callback[] arrcallback = (Callback[])t;
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b2 = cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b;
cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b2.CGLIB$CALLBACK_1 = (MethodInterceptor)arrcallback[1];
cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b2.CGLIB$CALLBACK_0 = (MethodInterceptor)arrcallback[0];
}
}
}
public Object newInstance(Callback[] arrcallback) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$SET_THREAD_CALLBACKS(arrcallback);
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$SET_THREAD_CALLBACKS(null);
return new CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b();
}
public Object newInstance(Callback callback) {
throw new IllegalStateException("More than one callback object required");
}
/*
* Unable to fully structure code
* Enabled aggressive block sorting
* Lifted jumps to return sites
*/
public Object newInstance(Class[] var1_1, Object[] var2_2, Callback[] var3_3) {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$SET_THREAD_CALLBACKS(var3_3);
switch (var1_1.length) {
case 0: {
** break;
}
}
throw new IllegalArgumentException("Constructor not found");
lbl6: // 1 sources:
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$SET_THREAD_CALLBACKS(null);
return new CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b();
}
public Callback getCallback(int n) {
MethodInterceptor methodInterceptor;
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)this);
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b = this;
switch (n) {
case 0: {
methodInterceptor = cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$CALLBACK_0;
break;
}
case 1: {
methodInterceptor = cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$CALLBACK_1;
break;
}
default: {
methodInterceptor = null;
}
}
return methodInterceptor;
}
public void setCallback(int n, Callback callback) {
switch (n) {
case 0: {
this.CGLIB$CALLBACK_0 = (MethodInterceptor)callback;
break;
}
case 1: {
this.CGLIB$CALLBACK_1 = (MethodInterceptor)callback;
break;
}
}
}
public Callback[] getCallbacks() {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$BIND_CALLBACKS((Object)this);
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b = this;
return new Callback[]{this.CGLIB$CALLBACK_0, this.CGLIB$CALLBACK_1};
}
public void setCallbacks(Callback[] arrcallback) {
Callback[] arrcallback2 = arrcallback;
this.CGLIB$CALLBACK_0 = (MethodInterceptor)arrcallback2[0];
Callback[] arrcallback3 = arrcallback2;
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b cglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b = this;
this.CGLIB$CALLBACK_1 = (MethodInterceptor)arrcallback2[1];
}
static {
CglibLearn$serviceImpl$$EnhancerByCGLIB$$4e65f4b.CGLIB$STATICHOOK1();
}
}
3.测试类的结果分析
自己的demo中
cglib.CglibProxy#intercept和cglib.CglibProxy2#intercept是如何工作的，即调用
impl.say();的时候
拦截器是如何拦截的
参照上面得到的decompile文件
final void say() {
MethodInterceptor methodInterceptor = this.CGLIB$CALLBACK_0;
if (methodInterceptor == null) {
CGLIB$BIND_CALLBACKS(this);
methodInterceptor = this.CGLIB$CALLBACK_0;
}
if (methodInterceptor != null) {
methodInterceptor.intercept(this, CGLIB$say$0$Method, CGLIB$emptyArgs, CGLIB$say$0$Proxy);
} else {
say();
}
}
很容易看出来了，
另外比较一下
image.png
这里就是CGLIB$CALLBACK_1了，这个是怎么办到的?
其实在之前讲net.sf.cglib.proxy.Enhancer#emitMethods时候就说了
net.sf.cglib.proxy.CallbackGenerator.Context#getIndex
配合net.sf.cglib.proxy.MethodInterceptorGenerator#generate里面
context.emitCallback(e, context.getIndex(method));
完成了每个method知道自己对应的callBack是第几个
另外，拦截器拦截时，
Object result = methodProxy.invokeSuper(o, objects);
invokeSuper是干吗的
这在下一节FastClass会讲
4.思考
4.1 CallbackFilter 和 CallBack有什么关系
一个method只能有一个CallBack(不定义也会有默认的)
CallBackFilter就是完成一个mapping的过程，比如
a,b method 用 A callBack
c,d method 用 B callBack
源码里也有体现出来一个method对应一个callBack
4.2 method与callBack之间的对应的关系是如何实现的
net.sf.cglib.proxy.Enhancer#emitMethods中
每个method通过 int index = filter.accept(actualMethod); 知道当前method由第几个callBack处理
然后由net.sf.cglib.proxy.MethodInterceptorGenerator#generate
context.emitCallback(e, context.getIndex(method));
将这种对应关系写到类中去
4.3 Enhancer如何根据callBack,callBackFilter完成代理类class文件的定义
net.sf.cglib.proxy.Enhancer#generateClass
主要是
net.sf.cglib.proxy.Enhancer#getMethods(java.lang.Class, java.lang.Class[], java.util.List, java.util.List, java.util.Set)
net.sf.cglib.proxy.Enhancer#emitMethods
4.4 与jdk动态代理区别
这里cglib底层是用的asm，而jdk动态代理没有
4.5 Enhancer的"enhance"体现在哪
个人理解，可能并不准确
1.完成callBack以及callBackFilter等的aop处理
2.完成代理类say()的调用 转发给 方法代理即CGLIB$say$0$Proxy
methodInterceptor.intercept(this, CGLIB$say$0$Method, CGLIB$emptyArgs, CGLIB$say$0$Proxy);
//其中
CGLIB$say$0$Proxy = MethodProxy.create(cls2, cls, "()V", "say", "CGLIB$say$0");
最终将cls2的say方法转发给cls的CGLIB$say$0方法(并不是上文列出来的CGLIB$say$0)，这个和fastClass相关，下一节再讲。
4.6 CGLIB$STATICHOOK1()作用
创建各种方法代理即MethodProxy,在下一节和fastClass一起讲
5.备注
net.sf.cglib.proxy.Enhancer#generateClass还有一些emit其他细节，目前没有涉及到，没有看
6.问题
findMethodProxy作用是啥，没有看到调用
7.refer
http://javadox.com/cglib/cglib/2.2/net/sf/cglib/proxy/Enhancer.html#generateClass(org.objectweb.asm.ClassVisitor)
http://cglib.sourceforge.net/apidocs/
http://www.cnblogs.com/cruze/p/3865180.html