JDK动态代理笔记

1、

/*** 被代理的接口*/public interface IBiz {    void fun();}

2、

/*** 被代理的接口实现*/public class BizImpl implements IBiz{    public void fun() {        System.out.println(">>>>BizImpl fun()");    }}

3、

import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;/** * 生成代理类的类 */public class ProxyBuilder implements InvocationHandler {    /**     * 被代理对象     */    Object target;    private ProxyBuilder(Object target) {        this.target = target;    }    /**     * 创建代理对象     */    public static Object getProxy(Object target){        return Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), new ProxyBuilder(target));    }    /**     * 代理处理逻辑     * @param proxy     * @param method     * @param args     * @return     * @throws Throwable     */    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {        Object result = null;        System.out.println(">>>>start:" + System.currentTimeMillis());        //执行被代理对象的方法        result = method.invoke(target, args);        System.out.println(">>>>end:" + System.currentTimeMillis());        return result;    }}

4、

/** * 使用动态代理 */public class Test {    public static void main(String[] args) {        IBiz biz = (IBiz) ProxyBuilder.getProxy(new BizImpl());        biz.fun();    }}

5、

    /**    * 将生成的代理类写到class文件    */    public static void createProxyClassFile() {        String name = "BizProxy";        byte[] data = ProxyGenerator.generateProxyClass(name, new Class[]{IBiz.class});        try {            FileOutputStream out = new FileOutputStream(name + ".class");            out.write(data);            out.close();        } catch (Exception e) {            e.printStackTrace();        }    }

6、生成的代理类

import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;import java.lang.reflect.Proxy;import java.lang.reflect.UndeclaredThrowableException;import proxy.IBiz;public final class BizProxy extends Proxy implements IBiz {    private static Method m1;    private static Method m3;    private static Method m0;    private static Method m2;    public BizProxy(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 fun() throws  {        try {            super.h.invoke(this, m3, (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);        }    }    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);        }    }    static {        try {            m1 = Class.forName("java.lang.Object").getMethod("equals", new Class[]{Class.forName("java.lang.Object")});            m3 = Class.forName("proxy.IBiz").getMethod("fun", new Class[0]);            m0 = Class.forName("java.lang.Object").getMethod("hashCode", new Class[0]);            m2 = Class.forName("java.lang.Object").getMethod("toString", new Class[0]);        } catch (NoSuchMethodException var2) {            throw new NoSuchMethodError(var2.getMessage());        } catch (ClassNotFoundException var3) {            throw new NoClassDefFoundError(var3.getMessage());        }    }}