Jad工具反编译JDK动态代理

港控/mmm° 2021-07-24 15:42 367阅读 0赞

**一 JDK动态代理生成对象的步骤**

1 获取被代理对象的引用，并且获取它的所有接口，反射获取。

2 JDK动态代理类生成一个新的类，同时新的类要实现被代理类实现的所有接口。

3 动态生成Java代码，新加的业务逻辑方法由一定的逻辑代码调用（在代码中体现）。

4 编译新生成的Java代码的.class

5 重新加载到JVM中运行。

**二 测试代码**

[https://gitee.com/cakin24/javatest/tree/master/src/main/java/Jdkproxy][https_gitee.com_cakin24_javatest_tree_master_src_main_java_Jdkproxy]

**三 将内存中的字节码输出到文件.class**

package Jdkproxy;
    
    import sun.misc.ProxyGenerator;
    import java.io.FileOutputStream;
    
    public class JDKProxyTest {
        public static void main( String[] args ) {
            try {
                Person obj = (Person)new JDKMeipo().getInstance(new Customer());
                //obj.findLove();
    
    
                //通过反编译工具可以查看源代码
                byte[] bytes = ProxyGenerator.generateProxyClass("$Proxy0",new Class[]{Person.class});
                FileOutputStream os = new FileOutputStream("E://$Proxy0.class");
                os.write(bytes);
                os.close();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

**四 Jad反编译工具**

下载地址：[http://www.javadecompilers.com/jad][http_www.javadecompilers.com_jad]

**五 反翻译命令**

E:\>jad -p $Proxy0.class > $Proxy.java

**六 $Proxy.java的内容**

// Decompiled by Jad v1.5.8g. Copyright 2001 Pavel Kouznetsov.
    // Jad home page: http://www.kpdus.com/jad.html
    // Decompiler options: packimports(3)
    
    
    import Jdkproxy.Person;
    import java.lang.reflect.*;
    
    
    public final class $Proxy0 extends Proxy
        implements Person
    {
    
    
        public $Proxy0(InvocationHandler invocationhandler)
        {
            super(invocationhandler);
        }
    
    
        public final boolean equals(Object obj)
        {
            try
            {
                return ((Boolean)super.h.invoke(this, m1, new Object[] {
                    obj
                })).booleanValue();
            }
            catch(Error _ex) { }
            catch(Throwable throwable)
            {
                throw new UndeclaredThrowableException(throwable);
            }
        }
    
    
        public final void findLove()
        {
            try
            {
                super.h.invoke(this, m3, null);
                return;
            }
            catch(Error _ex) { }
            catch(Throwable throwable)
            {
                throw new UndeclaredThrowableException(throwable);
            }
        }
    
    
        public final String toString()
        {
            try
            {
                return (String)super.h.invoke(this, m2, null);
            }
            catch(Error _ex) { }
            catch(Throwable throwable)
            {
                throw new UndeclaredThrowableException(throwable);
            }
        }
    
    
        public final int hashCode()
        {
            try
            {
                return ((Integer)super.h.invoke(this, m0, null)).intValue();
            }
            catch(Error _ex) { }
            catch(Throwable throwable)
            {
                throw new UndeclaredThrowableException(throwable);
            }
        }
    
    
        private static Method m1;
        private static Method m3;
        private static Method m2;
        private static Method m0;
    
    
        static
        {
            try
            {
                m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[] {
                    Class.forName("java.lang.Object")
                });
                m3 = Class.forName("Jdkproxy.Person").getMethod("findLove", new Class[0]);
                m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);
                m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);
            }
            catch(NoSuchMethodException nosuchmethodexception)
            {
                throw new NoSuchMethodError(nosuchmethodexception.getMessage());
            }
            catch(ClassNotFoundException classnotfoundexception)
            {
                throw new NoClassDefFoundError(classnotfoundexception.getMessage());
            }
        }
    }

[https_gitee.com_cakin24_javatest_tree_master_src_main_java_Jdkproxy]: https://gitee.com/cakin24/javatest/tree/master/src/main/java/Jdkproxy
[http_www.javadecompilers.com_jad]: http://www.javadecompilers.com/jad