jdk 代理 和 cglib 代理深度分析

参考 http://lrd.ele.me/2017/01/09/dynamic_proxy/

jdk 代理
rem  target 实例化的对象

--> Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), this);
--> Class<?> cl = getProxyClass0(loader, intfs);  // intfs 对象接口
重点 :
--> return proxyClassCache.get(loader, interfaces);  // proxyClassCache 缓存
-->  Object subKey = Objects.requireNonNull(subKeyFactory.apply(key, parameter)); // 获取subkey   [KeyFactory类型] subKeyFactory
--> Supplier<V> supplier = valuesMap.get(subKey); value 域  <ProxyClassFactory> 类型  supplier.apply() == ProxyClassFactory.apply()
--> Map<Class<?>, Boolean> interfaceSet = new IdentityHashMap<>(interfaces.length);
//Verify that the class loader resolves the name of this interface to the same Class object.
//Verify that the Class object actually represents an interface.
//Verify that this interface is not a duplicate.
--> interfaceClass = Class.forName(intf.getName(), false, loader);  // 逐个遍历 interfaces
--> long num = nextUniqueNumber.getAndIncrement();
--> String proxyName = proxyPkg + proxyClassNamePrefix + num; //生成名称
--> byte[] proxyClassFile = ProxyGenerator.generateProxyClass( proxyName, interfaces, accessFlags); // 生成classbyte  [核心]
--> return defineClass0(loader, proxyName,  proxyClassFile, 0, proxyClassFile.length); //定义类
--> factory = new Factory(key, parameter, subKey, valuesMap);// valueFactory 即 valuesMap 中 value 的封装
--> final Constructor<?> cons = cl.getConstructor(constructorParams);
--> final InvocationHandler ih = h;
--> return cons.newInstance(new Object[]{h});

--------------------------------------------
生成$Proxy0 class 反编译

static {
try {
m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
m2 = Class.forName("java.lang.Object").getMethod("toString");
m3 = Class.forName("BookFacade").getMethod("addBook");
m0 = Class.forName("java.lang.Object").getMethod("hashCode");
} catch (NoSuchMethodException var2) {
throw new NoSuchMethodError(var2.getMessage());
} catch (ClassNotFoundException var3) {
throw new NoClassDefFoundError(var3.getMessage());
}
}
生成的方法
public final void addBook() throws  {
try {
super.h.invoke(this, m3, (Object[])null);
} catch (RuntimeException | Error var2) {
throw var2;
} catch (Throwable var3) {
throw new UndeclaredThrowableException(var3);
}
}

jdk proxy的调用是一个反射调用的过程

cglib 动态代理的实现分析

代理类继承自org.springframework.cglib.proxy.MethodInterceptor  实现intercept方法
关键代码 ::
Enhancer enhancer = new Enhancer();
enhancer.setSuperclass(this.target.getClass()); // 将接口直接设置成BookFacadeProxyCglib 实现类
// 回调方法
// enhancer.setCallbackType(this.getClass());
enhancer.setCallback(this);     //设置回调
// 创建代理对象
return enhancer.create();
--> return this.createHelper();
-->  this.setNamePrefix(this.superclass.getName());设置NamePrefix
--> return super.create(KEY_FACTORY.newInstance(this.superclass != null ? this.superclass.getName() : null, ReflectUtils.getNames(this.interfaces), this.filter, this.callbackTypes, this.useFactory, this.interceptDuringConstruction, this.serialVersionUID));

// 代理产生的几个类

fastclass        --> public class BookFacadeImpl$$EnhancerByCGLIB$$677aba98$$FastClassByCGLIB$$dcb5b9cc extends FastClass
class            --> public class BookFacadeImpl$$EnhancerByCGLIB$$677aba98 extends BookFacadeImpl implements Factory
keyFactory       --> public class Enhancer$EnhancerKey$$KeyFactoryByCGLIB$$4ce19e8f extends KeyFactory implements EnhancerKey
methodwrapperkey --> public class MethodWrapper$MethodWrapperKey$$KeyFactoryByCGLIB$$552be97a extends KeyFactory implements MethodWrapperKey

调用路径
//使用的是这个对象
--> BookFacadeImpl$$EnhancerByCGLIB$$677aba98
|    private boolean CGLIB$BOUND;
|    private static final ThreadLocal CGLIB$THREAD_CALLBACKS;  //threadlocal 中存放callback
|    private static final Callback[] CGLIB$STATIC_CALLBACKS;   // static callback
|    private MethodInterceptor CGLIB$CALLBACK_0;               // 用户自己实现的MethodInterceptor
|    private static final Method CGLIB$addBook$0$Method;       // 父类中的callback 方法
|    private static final MethodProxy CGLIB$addBook$0$Proxy;   // 方法代理 MethodProxy 类
|    private static final Object[] CGLIB$emptyArgs;            // 方法参数
|    private static final Method CGLIB$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 var0 = Class.forName("BookFacadeImpl$$EnhancerByCGLIB$$677aba98"); //当前类的实例
|        Class var1;
|        Method[] var10000 = ReflectUtils.findMethods(new String[]{"finalize", "()V", "equals", "(Ljava/lang/Object;)Z", "toString", "()Ljava/lang/String;", "hashCode", "()I", "clone", "()Ljava/lang/Object;"}, (var1 = Class.forName("java.lang.Object")).getDeclaredMethods());
|        CGLIB$finalize$1$Method = var10000[0];
|        CGLIB$finalize$1$Proxy = MethodProxy.create(var1, var0, "()V", "finalize", "CGLIB$finalize$1");
|        CGLIB$equals$2$Method = var10000[1];
|        CGLIB$equals$2$Proxy = MethodProxy.create(var1, var0, "(Ljava/lang/Object;)Z", "equals", "CGLIB$equals$2");
|        CGLIB$toString$3$Method = var10000[2];
|        CGLIB$toString$3$Proxy = MethodProxy.create(var1, var0, "()Ljava/lang/String;", "toString", "CGLIB$toString$3");
|        CGLIB$hashCode$4$Method = var10000[3];
|        CGLIB$hashCode$4$Proxy = MethodProxy.create(var1, var0, "()I", "hashCode", "CGLIB$hashCode$4");
|        CGLIB$clone$5$Method = var10000[4];
|        CGLIB$clone$5$Proxy = MethodProxy.create(var1, var0, "()Ljava/lang/Object;", "clone", "CGLIB$clone$5");
// var1 赋值
|        CGLIB$addBook$0$Method = ReflectUtils.findMethods(new String[]{"addBook", "()V"}, (var1 = Class.forName("BookFacadeImpl")).getDeclaredMethods())[0];
|        CGLIB$addBook$0$Proxy = MethodProxy.create(var1, var0, "()V", "addBook", "CGLIB$addBook$0");
|    }
--> addBook()
-->
-->| public final void addBook() {
-->|     MethodInterceptor var10000 = this.CGLIB$CALLBACK_0;//获取当前类中的methodintercepter
-->|     if (this.CGLIB$CALLBACK_0 == null) {
-->|         CGLIB$BIND_CALLBACKS(this);                //如果为空
-->|         var10000 = this.CGLIB$CALLBACK_0;
-->|     }
-->|
-->|     if (var10000 != null) {
// 执行MethodInterceptor 类中的方法 <实现了MethodInterceptor的类> -->
-->|         var10000.intercept(this, CGLIB$addBook$0$Method, CGLIB$emptyArgs, CGLIB$addBook$0$Proxy);
-->|     } else {
-->|         super.addBook();
-->|     }
-->| }

-->| private static final void CGLIB$BIND_CALLBACKS(Object var0) {
-->|     BookFacadeImpl$$EnhancerByCGLIB$$677aba98 var1 = (BookFacadeImpl$$EnhancerByCGLIB$$677aba98)var0;
-->|     if (!var1.CGLIB$BOUND) {
-->|         var1.CGLIB$BOUND = true;
-->|         Object var10000 = CGLIB$THREAD_CALLBACKS.get();
-->|         if (var10000 == null) {
-->|             var10000 = CGLIB$STATIC_CALLBACKS;
-->|             if (CGLIB$STATIC_CALLBACKS == null) {
-->|                 return;
-->|             }
-->|        }
-->|
-->|         var1.CGLIB$CALLBACK_0 = (MethodInterceptor)((Callback[])var10000)[0];
-->|     }
-->|
-->| }

实现了 MethodInterceptor的类
-->|>|public class BookFacadeProxyCglib implements MethodInterceptor {
-->|>|    private Object target;
-->|>|
-->|>|    public Object getInstance(Object target) {
-->|>|        this.target = target;
-->|>|        Enhancer enhancer = new Enhancer();
-->|>|        enhancer.setSuperclass(this.target.getClass());
-->|>|        // 回调方法
-->|>|        // enhancer.set
b9d8
CallbackType(this.getClass());
-->|>|        enhancer.setCallback(this);
-->|>|        // 创建代理对象
-->|>|        return enhancer.create();
-->|>|    }
-->|>|
-->|>|    @Override
-->|>|    public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
-->|>|        System.out.println("before run!");
// 执行MethodProxy的invokeSuper
-->|>|        proxy.invokeSuper(obj, args);
-->|>|        System.out.println("after run!");
-->|>|        return null;
-->|>|    }
-->|>|}

MethodProxy的invokeSuper 方法
-->| public Object invokeSuper(Object obj, Object[] args) throws Throwable {
-->|     try {
-->|         this.init();

------> | private void init() {
------> |     if (this.fastClassInfo == null) {
------> |         Object var1 = this.initLock;
------> |         synchronized(this.initLock) {
------> |             if (this.fastClassInfo == null) {
------> |                 MethodProxy.CreateInfo ci = this.createInfo;
----------------------- 对应  --> CGLIB$addBook$0$Proxy = MethodProxy.create(var1, var0, "()V", "addBook", "CGLIB$addBook$0");
MethodProxy 中的变量赋值
[ c1 = var1 = BookFacadeImpl                            ]
[ c2 = var0 = BookFacadeImpl$$EnhancerByCGLIB$$677aba98 ]
[ name1 = addBook         = new Signature(name1, desc); ]
[ name2 = CGLIB$addBook$0 = new Signature(name2, desc); ]
--> | public static MethodProxy create(Class c1, Class c2, String desc, String name1, String name2) {
--> |     MethodProxy proxy = new MethodProxy();
--> |     proxy.sig1 = new Signature(name1, desc);
--> |     proxy.sig2 = new Signature(name2, desc);
--> |     proxy.createInfo = new MethodProxy.CreateInfo(c1, c2);
--> |     return proxy;
--> | }
-----------------------
------> |                 MethodProxy.FastClassInfo fci = new MethodProxy.FastClassInfo(); //实例化FastClassInfo
------> |                 fci.f1 = helper(ci, ci.c1);
----------------------------------------------------------------------------------------------------------------------
---->| private static FastClass helper(MethodProxy.CreateInfo ci, Class type) {
---->|    Generator g = new Generator();
---->|    g.setType(type);
---->|    g.setClassLoader(ci.c2.getClassLoader());
---->|    g.setNamingPolicy(ci.namingPolicy);
---->|    g.setStrategy(ci.strategy);
---->|    g.setAttemptLoad(ci.attemptLoad);
---->|    return g.create();
>| org.springframework.cglib.core.AbstractClassGenerator#create //最终调用AbstractClassGenerator的create方法
---->|   }
----------------------------------------------------------------------------------------------------------------------
------> |                 fci.f2 = helper(ci, ci.c2);
------> |                 fci.i1 = fci.f1.getIndex(this.sig1);
------> |                 fci.i2 = fci.f2.getIndex(this.sig2);
------> |                 this.fastClassInfo = fci;
------> |                 this.createInfo = null;
------> |             }
------> |         }
------> |     }
------> | }
-->|         MethodProxy.FastClassInfo fci = this.fastClassInfo;
-->|         return fci.f2.invoke(fci.i2, obj, args);
-->|     } catch (InvocationTargetException var4) {
-->|         throw var4.getTargetException();
-->|     }
-->| }