spring aop as cglib

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.length;i++) {
System.out.println("---->" + 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();
}
}