Java查看动态代理生成的代码

Java查看动态代理生成的代码

1.创建一个导出生成类的agent

agent是一个用来个jvm打交道的东西,需要实现一个静态的public static void premain(String agentArgs, Instrumentation inst) 方法.我使用如下的代码创建agent

package ctgu.jagent;

import java.io.File;
import java.io.FileOutputStream;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;

public class CustomAgent implements ClassFileTransformer {
 
	public static void premain(String agentArgs, Instrumentation inst) {
		inst.addTransformer(new CustomAgent());
	}

	@Override
	public byte[] transform(ClassLoader loader, String className, Class<?> classBeingRedefined,
			ProtectionDomain protectionDomain, byte[] classfileBuffer) throws IllegalClassFormatException {
		if (!className.startsWith("java") && !className.startsWith("sun")) {
			// 既不是java也不是sun开头的
			// 导出代码
			int lastIndexOf = className.lastIndexOf("/") + 1;
			String fileName = className.substring(lastIndexOf) + ".class";
			exportClazzToFile("E:/javaeeworkspace/bytecode/exported/", fileName, classfileBuffer);
			System.out.println(className + " --> EXPORTED Succeess!");
		}    
		return classfileBuffer;
	}

	/**
	 * 
	 * @param dirPath
	 *目录以/结尾,且必须存在
	 * @param fileName
	 * @param data
	 */
	private void exportClazzToFile(String dirPath, String fileName, byte[] data) {
		try {
			File file = new File(dirPath + fileName);
			if (!file.exists()) {
				file.createNewFile();    
			}    
			FileOutputStream fos = new FileOutputStream(file);
			fos.write(data);
			fos.close();    
		} catch (Exception e) {
			System.out.println("exception occured while doing some file operation");
			e.printStackTrace();
		}
	}
}

然后使用eclipse的导出功能导出jar(注意agent必须是jar的形式存在),在向导中使用指定的MANIFEST.MF文件,MANIFEST.MF文件的内容如下

Manifest-Version: 1.0
Premain-Class: ctgu.jagent.CustomAgent

注意,这个premain-Class就是带有premain静态方法的类。
如果你使用maven,也可以用如下plugin

<plugin>
	<groupId>org.apache.maven.plugins</groupId>
	<artifactId>maven-jar-plugin</artifactId>
	<configuration>
		<archive>
			<manifestFile>src/main/resources/META-INF/MANIFEST.MF</manifestFile>
		</archive>
	</configuration>
</plugin>

把manifestFile换成你存放自定义MANIFEST.MF的路径,然后mvn package就可以了。

导出的jar包这里假设叫jagent.jar

2. 使用jagent.jar

把jagent.jar放到工程下,运行的时候加上jvm参数

-javaagent:jagent.jar

注意:左右都没有空格,要是jvm提示找不到的话,可以用eclispe把jagent.jar加入到buildpath中。

3. 使用动态代理

3.0 原始目标的接口与实现

接口定义如下:

package ctgu.bytecode.proxy.service;

public interface HelloService {
 public String sayHello(String name) ;
}

实现如下:

package ctgu.bytecode.proxy.service.impl;    
import ctgu.bytecode.proxy.service.HelloService;    
public class HelloServiceImpl implements HelloService{    
	@Override
	public String sayHello(String name) {
		return "Hello "+name;
	}    	
}

3.1 使用jdk的代理

private static void javaDynamicProxy() {
	HelloService helloService=new HelloServiceImpl();
	MyInvocationHandler handler=new MyInvocationHandler(helloService);
	
	HelloService proxy = (HelloService)Proxy.newProxyInstance(HelloService.class.getClassLoader(), 
			new Class<?>[]{HelloService.class}, handler);
	
	
	String sayHello = proxy.sayHello("woober");
	
	System.out.println(sayHello);
}

其中MyInvocationHandler的代码如下:

package ctgu.bytecode.proxy;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

public class MyInvocationHandler implements InvocationHandler {

	Object trueTarget;
	
	public MyInvocationHandler(Object target) {
		this.trueTarget=target;
	}
	
	@Override
	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
		System.out.println("before invoke method:"+method.getName());
		Object result = method.invoke(trueTarget, args);
		System.out.println("invoke finish return:"+result);
		return result;
	}

}

运行后输出:

ctgu/bytecode/TestMain --> EXPORTED Succeess!    
ctgu/bytecode/proxy/service/impl/HelloServiceImpl --> EXPORTED Succeess!
ctgu/bytecode/proxy/service/HelloService --> EXPORTED Succeess!
ctgu/bytecode/proxy/MyInvocationHandler --> EXPORTED Succeess!
com/sun/proxy/$Proxy0 --> EXPORTED Succeess!
before invoke method:sayHello
invoke finish return:Hello woober
Hello woober

在第4部分会分析生成com/sun/proxy/$Proxy0的反编译代码。

3.2 使用cglib代理

private static void cgLibProxy(){		
	HelloService helloService=new HelloServiceImpl();
	MyMethodIntercepter intercepter=new MyMethodIntercepter(helloService);		 
	HelloService proxy = (HelloService)Enhancer.create(HelloService.class,intercepter);
	System.err.println("Proxy class name is "+proxy.getClass().getName());
	System.out.println(proxy.sayHello("Woober"));
}

其中MyMethodIntercepter代码如下:

package ctgu.bytecode.proxy;

import java.lang.reflect.Method;    
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

public class MyMethodIntercepter  implements MethodInterceptor{

	Object trueTarget;
	
	public MyMethodIntercepter(Object target) {
		 trueTarget=target;
	}
	@Override
	public Object intercept(Object obj, Method method, Object[] args, MethodProxy proxy) throws Throwable {
		System.out.println("In cglib before invoke");
		//这个methodProxy 是目标方法的一个代理,下面可以看出来    		 
		 Object result = proxy.invoke(trueTarget, args);
		System.out.println("In cglib after invoke");
		return result;
	}
}

运行输出:

ctgu/bytecode/TestMain --> EXPORTED Succeess!
net/sf/cglib/proxy/Callback --> EXPORTED Succeess!
ctgu/bytecode/proxy/service/impl/HelloServiceImpl --> EXPORTED Succeess!
ctgu/bytecode/proxy/service/HelloService --> EXPORTED Succeess!
ctgu/bytecode/proxy/MyMethodIntercepter --> EXPORTED Succeess!
net/sf/cglib/proxy/MethodInterceptor --> EXPORTED Succeess!
net/sf/cglib/proxy/Enhancer --> EXPORTED Succeess!
中间省略大量cglib的类还有asm的类.....  

ctgu/bytecode/proxy/service/HelloService$$EnhancerByCGLIB$$1af19a1d --> EXPORTED Succeess!

net/sf/cglib/proxy/MethodProxy --> EXPORTED Succeess!
net/sf/cglib/proxy/MethodProxy$CreateInfo --> EXPORTED Succeess!

In cglib before invoke

Proxy class name is ctgu.bytecode.proxy.service.HelloService$$EnhancerByCGLIB$$1af19a1d

省略大量cglib的类...

ctgu/bytecode/proxy/service/HelloService$$FastClassByCGLIB$$c2826506 --> EXPORTED Succeess!

ctgu/bytecode/proxy/service/HelloService$$EnhancerByCGLIB$$1af19a1d$$FastClassByCGLIB$$a45a31f6 --> EXPORTED Succeess!

In cglib after invoke

Hello Woober

注意这两句话的顺序

In cglib before invoke
Proxy class name is ctgu.bytecode.proxy.service.HelloService$$EnhancerByCGLIB$$1af19a1d

按理说后面应该在后面这句应该在前面的,因为我使用system.err打的Proxy class name is这一句,跟out不是同一个流,所以以顺序不对(因为err会在eclipse里面标红,比较好看...)

下面重点关注ctgu.bytecode.proxy.service.HelloService$$EnhancerByCGLIB$$1af19a1d这个类

4. 查看生成类的源码

找一个顺手的反编译器,我用的是Bytecode Viewer ,github地址https://github.com/Konloch/bytecode-viewer

4.1 JDK动态代理反编译

/*
 * Decompiled with CFR 0_110.
 * 
 * Could not load the following classes:
 *  com.sun.proxy.$Proxy0
 *  ctgu.bytecode.proxy.service.HelloService
 */
package com.sun.proxy;

import ctgu.bytecode.proxy.service.HelloService;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.lang.reflect.UndeclaredThrowableException;

public final class $Proxy0
extends Proxy
implements HelloService {
    private static Method m1;
    private static Method m3;
    private static Method m2;
    private static Method m0;

    public $Proxy0(InvocationHandler invocationHandler) {
        super(invocationHandler);
    }

    public final boolean equals(Object object) {
        try {
            return (Boolean)this.h.invoke((Object)this, m1, new Object[]{object});
        }
        catch (Error | RuntimeException v0) {
            throw v0;
        }
        catch (Throwable var2_2) {
            throw new UndeclaredThrowableException(var2_2);
        }
    }

    public final String sayHello(String string) {
        try {
            return (String)this.h.invoke((Object)this, m3, new Object[]{string});
        }
        catch (Error | RuntimeException v0) {
            throw v0;
        }
        catch (Throwable var2_2) {
            throw new UndeclaredThrowableException(var2_2);
        }
    }

    public final String toString() {
        try {
            return (String)this.h.invoke((Object)this, m2, null);
        }
        catch (Error | RuntimeException v0) {
            throw v0;
        }
        catch (Throwable var1_1) {
            throw new UndeclaredThrowableException(var1_1);
        }
    }

    public final int hashCode() {
        try {
            return (Integer)this.h.invoke((Object)this, m0, null);
        }
        catch (Error | RuntimeException v0) {
            throw v0;
        }
        catch (Throwable var1_1) {
            throw new UndeclaredThrowableException(var1_1);
        }
    }

    static {
        try {
            m1 = Class.forName("java.lang.Object").getMethod("equals", Class.forName("java.lang.Object"));
            m3 = Class.forName("ctgu.bytecode.proxy.service.HelloService").getMethod("sayHello", Class.forName("java.lang.String"));
            m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
            m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
            return;
        }
        catch (NoSuchMethodException var1) {
            throw new NoSuchMethodError(var1.getMessage());
        }
        catch (ClassNotFoundException var1_1) {
            throw new NoClassDefFoundError(var1_1.getMessage());
        }
    }
}

可以看出来他实现了HelloService接口,实现了sayHello方法,实际调用的时候是使用的invocationHandler并且传入了m3,m3实际就是靠反射拿到的接口中的sayHello方法。

m3 = Class.forName("ctgu.bytecode.proxy.service.HelloService").getMethod("sayHello", Class.forName("java.lang.String"));

4.2 CGLIB动态代理反编译

package ctgu.bytecode.proxy.service;

import java.lang.reflect.*;
import net.sf.cglib.proxy.*;
import net.sf.cglib.core.*;

public class HelloService$$EnhancerByCGLIB$$1af19a1d implements HelloService, 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 static final Method CGLIB$finalize$0$Method;
    private static final MethodProxy CGLIB$finalize$0$Proxy;
    private static final Object[] CGLIB$emptyArgs;
    private static final Method CGLIB$equals$1$Method;
    private static final MethodProxy CGLIB$equals$1$Proxy;
    private static final Method CGLIB$toString$2$Method;
    private static final MethodProxy CGLIB$toString$2$Proxy;
    private static final Method CGLIB$hashCode$3$Method;
    private static final MethodProxy CGLIB$hashCode$3$Proxy;
    private static final Method CGLIB$clone$4$Method;
    private static final MethodProxy CGLIB$clone$4$Proxy;
    private static final Method CGLIB$sayHello$5$Method;
    private static final MethodProxy CGLIB$sayHello$5$Proxy;
    
    static void CGLIB$STATICHOOK1() {
        CGLIB$THREAD_CALLBACKS = new ThreadLocal();
        CGLIB$emptyArgs = new Object[0];
        final Class<?> forName = Class.forName("ctgu.bytecode.proxy.service.HelloService$$EnhancerByCGLIB$$1af19a1d");
        final Class<?> forName2;
        final Method[] methods = ReflectUtils.findMethods(new String[] { "finalize", "()V", "equals", "(Ljava/lang/Object;)Z", "toString", "()Ljava/lang/String;", "hashCode", "()I", "clone", "()Ljava/lang/Object;" }, (forName2 = Class.forName("java.lang.Object")).getDeclaredMethods());
        CGLIB$finalize$0$Method = methods[0];
        CGLIB$finalize$0$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "()V", "finalize", "CGLIB$finalize$0");
        CGLIB$equals$1$Method = methods[1];
        CGLIB$equals$1$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "(Ljava/lang/Object;)Z", "equals", "CGLIB$equals$1");
        CGLIB$toString$2$Method = methods[2];
        CGLIB$toString$2$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "()Ljava/lang/String;", "toString", "CGLIB$toString$2");
        CGLIB$hashCode$3$Method = methods[3];
        CGLIB$hashCode$3$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "()I", "hashCode", "CGLIB$hashCode$3");
        CGLIB$clone$4$Method = methods[4];
        CGLIB$clone$4$Proxy = MethodProxy.create((Class)forName2, (Class)forName, "()Ljava/lang/Object;", "clone", "CGLIB$clone$4");
        final Class<?> forName3;
        CGLIB$sayHello$5$Method = ReflectUtils.findMethods(new String[] { "sayHello", "(Ljava/lang/String;)Ljava/lang/String;" }, (forName3 = Class.forName("ctgu.bytecode.proxy.service.HelloService")).getDeclaredMethods())[0];
        CGLIB$sayHello$5$Proxy = MethodProxy.create((Class)forName3, (Class)forName, "(Ljava/lang/String;)Ljava/lang/String;", "sayHello", "CGLIB$sayHello$5");
    }
    
    final void CGLIB$finalize$0() throws Throwable {
        super.finalize();
    }
    
    protected final void finalize() throws Throwable {
        MethodInterceptor cglib$CALLBACK_2;
        MethodInterceptor cglib$CALLBACK_0;
        if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
            CGLIB$BIND_CALLBACKS(this);
            cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
        }
        if (cglib$CALLBACK_0 != null) {
            cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$finalize$0$Method, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$emptyArgs, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$finalize$0$Proxy);
            return;
        }
        super.finalize();
    }
    
    final boolean CGLIB$equals$1(final Object o) {
        return super.equals(o);
    }
    
    public final boolean equals(final Object o) {
        MethodInterceptor cglib$CALLBACK_2;
        MethodInterceptor cglib$CALLBACK_0;
        if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
            CGLIB$BIND_CALLBACKS(this);
            cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
        }
        if (cglib$CALLBACK_0 != null) {
            final Object intercept = cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$equals$1$Method, new Object[] { o }, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$equals$1$Proxy);
            return intercept != null && (boolean)intercept;
        }
        return super.equals(o);
    }
    
    final String CGLIB$toString$2() {
        return super.toString();
    }
    
    public final String toString() {
        MethodInterceptor cglib$CALLBACK_2;
        MethodInterceptor cglib$CALLBACK_0;
        if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
            CGLIB$BIND_CALLBACKS(this);
            cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
        }
        if (cglib$CALLBACK_0 != null) {
            return (String)cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$toString$2$Method, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$emptyArgs, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$toString$2$Proxy);
        }
        return super.toString();
    }
    
    final int CGLIB$hashCode$3() {
        return super.hashCode();
    }
    
    public final int hashCode() {
        MethodInterceptor cglib$CALLBACK_2;
        MethodInterceptor cglib$CALLBACK_0;
        if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
            CGLIB$BIND_CALLBACKS(this);
            cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
        }
        if (cglib$CALLBACK_0 != null) {
            final Object intercept = cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$hashCode$3$Method, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$emptyArgs, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$hashCode$3$Proxy);
            return (intercept == null) ? 0 : ((Number)intercept).intValue();
        }
        return super.hashCode();
    }
    
    final Object CGLIB$clone$4() throws CloneNotSupportedException {
        return super.clone();
    }
    
    protected final Object clone() throws CloneNotSupportedException {
        MethodInterceptor cglib$CALLBACK_2;
        MethodInterceptor cglib$CALLBACK_0;
        if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
            CGLIB$BIND_CALLBACKS(this);
            cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
        }
        if (cglib$CALLBACK_0 != null) {
            return cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$clone$4$Method, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$emptyArgs, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$clone$4$Proxy);
        }
        return super.clone();
    }
    
    final String CGLIB$sayHello$5(final String s) {
        return super.sayHello(s);
    }
    
    public final String sayHello(final String s) {
        MethodInterceptor cglib$CALLBACK_2;
        MethodInterceptor cglib$CALLBACK_0;
        if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
            CGLIB$BIND_CALLBACKS(this);
            cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
        }
        if (cglib$CALLBACK_0 != null) {
            return (String)cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Method, new Object[] { s }, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Proxy);
        }
        return super.sayHello(s);
    }
    
    public static MethodProxy CGLIB$findMethodProxy(final Signature signature) {
        final String string = signature.toString();
        switch (string.hashCode()) {
            case -1816210712: {
                if (string.equals("sayHello(Ljava/lang/String;)Ljava/lang/String;")) {
                    return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Proxy;
                }
                break;
            }
            case -1574182249: {
                if (string.equals("finalize()V")) {
                    return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$finalize$0$Proxy;
                }
                break;
            }
            case -508378822: {
                if (string.equals("clone()Ljava/lang/Object;")) {
                    return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$clone$4$Proxy;
                }
                break;
            }
            case 1826985398: {
                if (string.equals("equals(Ljava/lang/Object;)Z")) {
                    return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$equals$1$Proxy;
                }
                break;
            }
            case 1913648695: {
                if (string.equals("toString()Ljava/lang/String;")) {
                    return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$toString$2$Proxy;
                }
                break;
            }
            case 1984935277: {
                if (string.equals("hashCode()I")) {
                    return HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$hashCode$3$Proxy;
                }
                break;
            }
        }
        return null;
    }
    
    public HelloService$$EnhancerByCGLIB$$1af19a1d() {
        CGLIB$BIND_CALLBACKS(this);
    }
    
    public static void CGLIB$SET_THREAD_CALLBACKS(final Callback[] array) {
        HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$THREAD_CALLBACKS.set(array);
    }
    
    public static void CGLIB$SET_STATIC_CALLBACKS(final Callback[] cglib$STATIC_CALLBACKS) {
        CGLIB$STATIC_CALLBACKS = cglib$STATIC_CALLBACKS;
    }
    
    private static final void CGLIB$BIND_CALLBACKS(final Object o) {
        final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = (HelloService$$EnhancerByCGLIB$$1af19a1d)o;
        if (!helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$BOUND) {
            helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$BOUND = true;
            Object o2;
            if ((o2 = HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$THREAD_CALLBACKS.get()) != null || (o2 = HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$STATIC_CALLBACKS) != null) {
                helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$CALLBACK_0 = (MethodInterceptor)((Callback[])o2)[0];
            }
        }
    }
    
    public Object newInstance(final Callback[] array) {
        CGLIB$SET_THREAD_CALLBACKS(array);
        final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
        CGLIB$SET_THREAD_CALLBACKS(null);
        return helloService$$EnhancerByCGLIB$$1af19a1d;
    }
    
    public Object newInstance(final Callback callback) {
        CGLIB$SET_THREAD_CALLBACKS(new Callback[] { callback });
        final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
        CGLIB$SET_THREAD_CALLBACKS(null);
        return helloService$$EnhancerByCGLIB$$1af19a1d;
    }
    
    public Object newInstance(final Class[] array, final Object[] array2, final Callback[] array3) {
        CGLIB$SET_THREAD_CALLBACKS(array3);
        switch (array.length) {
            case 0: {
                final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
                CGLIB$SET_THREAD_CALLBACKS(null);
                return helloService$$EnhancerByCGLIB$$1af19a1d;
            }
            default: {
                throw new IllegalArgumentException("Constructor not found");
            }
        }
    }
    
    public Callback getCallback(final int n) {
        CGLIB$BIND_CALLBACKS(this);
        Object cglib$CALLBACK_0 = null;
        switch (n) {
            case 0: {
                cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0;
                break;
            }
            default: {
                cglib$CALLBACK_0 = null;
                break;
            }
        }
        return (Callback)cglib$CALLBACK_0;
    }
    
    public void setCallback(final int n, final Callback callback) {
        switch (n) {
            case 0: {
                this.CGLIB$CALLBACK_0 = (MethodInterceptor)callback;
                break;
            }
        }
    }
    
    public Callback[] getCallbacks() {
        CGLIB$BIND_CALLBACKS(this);
        return new Callback[] { this.CGLIB$CALLBACK_0 };
    }
    
    public void setCallbacks(final Callback[] array) {
        this.CGLIB$CALLBACK_0 = (MethodInterceptor)array[0];
    }
    
    static {
        CGLIB$STATICHOOK1();
    }
}

生成的类同样实现了 HelloService接口并且实现了Factory接口,Factory接口如下:

public interface Factory {
    
    Object newInstance(Callback callback);	    
     
    Object newInstance(Callback[] callbacks);	
    
    Object newInstance(Class[] types, Object[] args, Callback[] callbacks);	
   
    Callback getCallback(int index);
 
    void setCallback(int index, Callback callback);	
    
    void setCallbacks(Callback[] callbacks);	
     
    Callback[] getCallbacks();
}

直接看生成的sayHello实现

  public final String sayHello(final String s) {
        MethodInterceptor cglib$CALLBACK_2;
        MethodInterceptor cglib$CALLBACK_0;
        if ((cglib$CALLBACK_0 = (cglib$CALLBACK_2 = this.CGLIB$CALLBACK_0)) == null) {
            CGLIB$BIND_CALLBACKS(this);
            cglib$CALLBACK_2 = (cglib$CALLBACK_0 = this.CGLIB$CALLBACK_0);
        }
        if (cglib$CALLBACK_0 != null) {
            return (String)cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Method, new Object[] { s }, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Proxy);
        }
        return super.sayHello(s);
    }

可以看到cglib$CALLBACK_0是通过CGLIB$BIND_CALLBACKS(this)完成的,glib$CALLBACK_2跟glib$CALLBACK_2是一个东西。

再看CGLIB$BIND_CALLBACKS(this)做了啥

private static final void CGLIB$BIND_CALLBACKS(final Object o) {
    final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = (HelloService$$EnhancerByCGLIB$$1af19a1d)o;
    if (!helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$BOUND) {
        helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$BOUND = true;
        Object o2;
        if ((o2 = HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$THREAD_CALLBACKS.get()) != null || (o2 = HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$STATIC_CALLBACKS) != null) {
            helloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$CALLBACK_0 = (MethodInterceptor)((Callback[])o2)[0];
        }
    }
}

CGLIB$CALLBACK_0是CGLIB$THREAD_CALLBACKS.get()或者CGLIB$STATIC_CALLBACKS,
CGLIB$THREAD_CALLBACKS是一个threadlocal的成员变量。

CGLIB$THREAD_CALLBACKS是由下面的CGLIB$SET_THREAD_CALLBACKS方法来设置的,

public static void CGLIB$SET_THREAD_CALLBACKS(final Callback[] array) {
    HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$THREAD_CALLBACKS.set(array);
}

这个方法被Factory接口的newInstance调用

public Object newInstance(final Callback[] array) {
    CGLIB$SET_THREAD_CALLBACKS(array);
    final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
    CGLIB$SET_THREAD_CALLBACKS(null);
    return helloService$$EnhancerByCGLIB$$1af19a1d;
}

public Object newInstance(final Callback callback) {
    CGLIB$SET_THREAD_CALLBACKS(new Callback[] { callback });
    final HelloService$$EnhancerByCGLIB$$1af19a1d helloService$$EnhancerByCGLIB$$1af19a1d = new HelloService$$EnhancerByCGLIB$$1af19a1d();
    CGLIB$SET_THREAD_CALLBACKS(null);
    return helloService$$EnhancerByCGLIB$$1af19a1d;
}

我看不懂的就是他为什么 CGLIB$SET_THREAD_CALLBACKS(array); 之后又 CGLIB$SET_THREAD_CALLBACKS(null); ???反编译的问题?

对于CGLIB$STATIC_CALLBACKS是由

public static void CGLIB$SET_STATIC_CALLBACKS(final Callback[] cglib$STATIC_CALLBACKS) {
    CGLIB$STATIC_CALLBACKS = cglib$STATIC_CALLBACKS;
}

这个方法赋值上的,但是我没找到调用的地方。

最后看实际上执行的方法的地方,就是掉的intercepter的intercept方法。

(String)cglib$CALLBACK_2.intercept((Object)this, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Method, new Object[] { s }, HelloService$$EnhancerByCGLIB$$1af19a1d.CGLIB$sayHello$5$Proxy);

最后一个参数是个MethodProxy

 CGLIB$sayHello$5$Proxy = MethodProxy.create((Class)forName3, (Class)forName, "(Ljava/lang/String;)Ljava/lang/String;", "sayHello", "CGLIB$sayHello$5");

我猜应该是对方法生成了一个代理

final String CGLIB$sayHello$5(final String s) {
    return super.sayHello(s);
}

关于这个cglib生成的字节码好多反编译工具都不能解析。不保证上面生成代码的正确性

posted @ 2015-12-01 23:08  ctgulong  阅读(9092)  评论(0编辑  收藏  举报