大家都知道spring的aop.而底层是用了jdk的动态代理，还有cglib.

一般来说代理接口的话就用jdk的动态代理。而当没有接口的时候就用cglib

jdk的动态代理底层是通过生成一个子类实现目标接口，继承 Proxy类，然后在加上eqs ,tostring,hashcode方法

而cglib及可以代理接口，也可以代理类。底层是通过生成一个子类来继承目标类。然后重写里面的方法。因为是继承,所以fianl的方法是重写不了的，代理不了的。下面来看一下cglib具体的代理是如何实现的。

接口类package org.tatan.test;    public interface Worker {        void doSomeWork(int numOfTimes);    }    目标类package org.tatan.test;public class WorkerBean implements Worker {    public void doSomeWork(int numOfTimes) {        for (int i = 0; i < numOfTimes; i++) {            System.out.print("");        }    }}Advice执行流程package org.tatan.test;import java.lang.reflect.Method;import org.aopalliance.intercept.MethodInterceptor;import org.aopalliance.intercept.MethodInvocation;public class AroundAdvice implements MethodInterceptor {    public Object invoke(MethodInvocation invocation) throws Throwable {             Object returnValue = invocation.proceed();        Method m = invocation.getMethod();        Object target = invocation.getThis();        Object[] args = invocation.getArguments();        System.out.println("Executed method: " + m.getName());        System.out.println("On object of type: " + target.getClass().getName());        System.out.println("With arguments:");        for (int i=0;i
    
     " + args[i]);        }        System.out.println();               return returnValue;    }}运行package org.tatan.test;import org.springframework.aop.framework.ProxyFactory;public class AOPExample2 {    public static void main(String[] args) {        Worker bean = getWorkerBean();        bean.doSomeWork(100000000);    }    private static Worker getWorkerBean() {        WorkerBean target = new WorkerBean();        ProxyFactory pf = new ProxyFactory();        pf.setTarget(target);        pf.addAdvice(new AroundAdvice());        pf.setInterfaces(new Class[]{Worker.class});        return (Worker) pf.getProxy();    }}如果调用了setInterfaces();就不要cglib了，使用JDK Dynamic Proxies，只是使用JDK Dynamic Proxies程序执行的效率比较低。使用CGLIB的Frozen效率比标准的CGLIB效率高。package org.tatan.test;import org.springframework.aop.framework.ProxyFactory;public class AOPExample2 {    public static void main(String[] args) {        Worker bean = getWorkerBean();        bean.doSomeWork(100000000);    }    private static Worker getWorkerBean() {        WorkerBean target = new WorkerBean();        ProxyFactory pf = new ProxyFactory();        pf.setTarget(target);        pf.addAdvice(new AroundAdvice());     //  pf.setInterfaces(new Class[]{Worker.class});        pf.setFrozen(true);        return (Worker) pf.getProxy();    }}