动态代理-初级篇

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最近想总结一下java的动态代理，动态代理有很多种实现方案，下面介绍三种最常用的动态搭理方案：1.jdk自带动态代理2.javassist实现动态代理3.cglib实现动态代理

接口和实现类代码：

package com.java.day1.dynamicproxy.one;public interface Interface {void doSomeThing();}

package com.java.day1.dynamicproxy.one;public class RealSubject   implements Interface{@Overridepublic void doSomeThing() {System.out.println("do some things..");}}

jdk自带动态搭理实现

package com.java.day1.dynamicproxy.one;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Method;public class JdkProxyHandler  implements InvocationHandler{//　这个就是我们要代理的真实对象    private Object subject;    //    构造方法，给我们要代理的真实对象赋初值    public JdkProxyHandler(Object subject) {        this.subject = subject;    }@Overridepublic Object invoke(Object proxy, Method method, Object[] args) throws Throwable {System.out.println("do otherthings..jdk..");return method.invoke(subject, args); }}

package com.java.day1.dynamicproxy.one;import java.lang.reflect.InvocationHandler;import java.lang.reflect.Proxy;public class JdkTest {public static void main(String[] args) {//被代理的类RealSubject rs = new RealSubject();// 代理增强类InvocationHandler ih = new JdkProxyHandler(rs);// 用java反射生成代理类Interface proxy = (Interface) Proxy.newProxyInstance(ih.getClass().getClassLoader(), rs.getClass().getInterfaces(), ih);proxy.doSomeThing();}}

javassist实现动态代理

package com.java.day1.dynamicproxy.one;import java.lang.reflect.Method;import javassist.util.proxy.MethodHandler;public class JavassitInterceptor implements MethodHandler{private Object subject;public JavassitInterceptor(Object subject){this.subject = subject;}@Overridepublic Object invoke(Object self, Method m, Method prosess, Object[] args) throws Throwable {System.out.println("do other thing..javassist.");return m.invoke(subject, args);}}

package com.java.day1.dynamicproxy.one;import javassist.util.proxy.ProxyFactory;import javassist.util.proxy.ProxyObject;public class javassistTest {public static void main(String[] args) throws Exception {//被代理的类RealSubject rs = new RealSubject();// 代理增强类JavassitInterceptor ih = new JavassitInterceptor(rs);// 用javassist反射生成代理类    ProxyFactory pf = new ProxyFactory();    pf.setInterfaces(rs.getClass().getInterfaces());   Class<?>  proxyClass = pf.createClass();   Interface proxy = (Interface) proxyClass.newInstance();   ((ProxyObject)proxy).setHandler(ih);   proxy.doSomeThing(); }}

cglib实现动态搭理

package com.java.day1.dynamicproxy.one;import java.lang.reflect.Method;import net.sf.cglib.proxy.MethodInterceptor;import net.sf.cglib.proxy.MethodProxy;public class CglibInterceptor implements MethodInterceptor {private Object subject;public CglibInterceptor(Object subject){this.subject = subject;}@Overridepublic  Object intercept(Object object, Method method, Object[] objects,  MethodProxy methodProxy) throws Throwable  {System.out.println("do other things..cglib...");return methodProxy.invoke(subject, objects);}}

package com.java.day1.dynamicproxy.one;import net.sf.cglib.proxy.Enhancer;public class CgligTest {public static void main(String[] args) {//被代理的类RealSubject rs = new RealSubject();// 代理增强类    Enhancer enhancer = new Enhancer();    CglibInterceptor  ci = new CglibInterceptor(rs);    enhancer.setCallback(ci);        enhancer.setInterfaces(rs.getClass().getInterfaces());            Interface proxy = (Interface)enhancer.create();        proxy.doSomeThing();}}

我还做了实验，但从创建来看jdk是最快的cglib最慢，但创建好后调用，javassist最快，jdk次之，不过是同一个数量级的，cglib最慢比其他2种慢5倍

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