被代理的类及其实现的接口

package proxy.demo;public interface ServiceDemo {    /**     * 返回姓名     */    void getName();    /**     * 返回年龄     */    void getAge();}

package proxy.demo;public class ServiceDemoImpl implements ServiceDemo {    @Override    public void getName() {        System.out.println("kevin");    }    @Override    public void getAge() {        System.out.println("20");    }}

为ServiceDemoImpl动态创建代理类

首先编写InvocationHandler

package proxy.demo;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;public class MyInvocationHandler implements InvocationHandler {    private Object target;//被代理的对象，通过构造函数传入    public MyInvocationHandler(Object target){        this.target = target;    }    @Override    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {                System.out.println("before");//调用目标方法前执行的代码        Object result = method.invoke(target, args);        System.out.println("after");//调用目标方法后调用的代码         return result;    }}

创建代理类并调用

import proxy.demo.Demo2;import proxy.demo.MyInvocationHandler;import proxy.demo.ServiceDemo;import proxy.demo.ServiceDemoImpl;import sun.misc.ProxyGenerator;import java.io.FileOutputStream;import java.io.IOException;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Proxy;/** * Created with IntelliJ IDEA * * @Author: bit hup * @Date: 11/10 0010 * @Time: 18:17 */public class Demo {    public static void main(String[] args) throws Exception {        ServiceDemo serviceDemo = new ServiceDemoImpl();               //创建InvocationHandler，注入被代理类的实例        InvocationHandler invocationHandler = new MyInvocationHandler(serviceDemo);        //获取代理类对象        ServiceDemo serviceDemoProxy = (ServiceDemo) Proxy.newProxyInstance(serviceDemo.getClass().getClassLoader(),                serviceDemo.getClass().getInterfaces(),invocationHandler);        //将动态创建的代理类写入到磁盘class文件中，然后反编译查看生成的代码        String path = "D://$Proxy0.class";        byte[] classFile = ProxyGenerator.generateProxyClass("$Proxy0",serviceDemo.getClass().getInterfaces());        FileOutputStream out = null;        try {            out = new FileOutputStream(path);            out.write(classFile);            out.flush();        } catch (Exception e) {            e.printStackTrace();        } finally {            try {                out.close();            } catch (IOException e) {                e.printStackTrace();            }        }        //调用代理类        serviceDemoProxy.getName();        serviceDemoProxy.getAge();    }}

生产的代理类，反编译后的代码

//// Source code recreated from a .class file by IntelliJ IDEA// (powered by Fernflower decompiler)//import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import java.lang.reflect.UndeclaredThrowableException;import proxy.demo.ServiceDemo;public final class $Proxy0 extends Proxy implements ServiceDemo {    private static Method m1;    private static Method m3;    private static Method m2;    private static Method m4;    private static Method m0;    public $Proxy0(InvocationHandler var1) throws  {        super(var1);    }    public final boolean equals(Object var1) throws  {        try {            return ((Boolean)super.h.invoke(this, m1, new Object[]{var1})).booleanValue();        } catch (RuntimeException | Error var3) {            throw var3;        } catch (Throwable var4) {            throw new UndeclaredThrowableException(var4);        }    }    public final void getName() throws  {        try {            super.h.invoke(this, m3, (Object[])null);        } catch (RuntimeException | Error var2) {            throw var2;        } catch (Throwable var3) {            throw new UndeclaredThrowableException(var3);        }    }    public final String toString() throws  {        try {            return (String)super.h.invoke(this, m2, (Object[])null);        } catch (RuntimeException | Error var2) {            throw var2;        } catch (Throwable var3) {            throw new UndeclaredThrowableException(var3);        }    }    public final void getAge() throws  {        try {            super.h.invoke(this, m4, (Object[])null);        } catch (RuntimeException | Error var2) {            throw var2;        } catch (Throwable var3) {            throw new UndeclaredThrowableException(var3);        }    }    public final int hashCode() throws  {        try {            return ((Integer)super.h.invoke(this, m0, (Object[])null)).intValue();        } catch (RuntimeException | Error var2) {            throw var2;        } catch (Throwable var3) {            throw new UndeclaredThrowableException(var3);        }    }    static {        try {            m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[]{Class.forName("java.lang.Object")});            m3 = Class.forName("proxy.demo.ServiceDemo").getMethod("getName", new Class[0]);            m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);            m4 = Class.forName("proxy.demo.ServiceDemo").getMethod("getAge", new Class[0]);            m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);        } catch (NoSuchMethodException var2) {            throw new NoSuchMethodError(var2.getMessage());        } catch (ClassNotFoundException var3) {            throw new NoClassDefFoundError(var3.getMessage());        }    }}

1.静态代理三种角色