spring2.5学习笔记（六）：AOP（1）用JDK中的Proxy实现与用CGlib实现的比较

这里我们就需要用到cglib-nodep-2.1_3.jar这个包

下面代码是演示的是一个用户权限判断，并赋予这个用户相应的操作。这里我做的是这样的用户权限设置：只要用户名不为空，那么就赋予它操作目标类中的所有方法的权利

代码一：

package cn.itcast.service;
public interface IPersonService {
	public void save(String name);
}

代码二 CGlibProxyFactory.java和JDKProxyFactory.java

package cn.itcast.service.aop;
import java.lang.reflect.Method;
import cn.itcast.service.impl.personServiceBean;
import net.sf.cglib.proxy.Enhancer;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;
public class CGlibProxyFactory implements MethodInterceptor{
	private Object targetObject;
	public Object createProxyIntance(Object targetObject){
		this.targetObject = targetObject;
		Enhancer enhancer = new Enhancer();
		enhancer.setSuperclass(this.targetObject.getClass());//CGlib是集成目标类，然后覆盖目标类中的非final方法，这样达到代理的效果
		enhancer.setCallback(this);
		return enhancer.create();
	}
	public Object intercept(Object proxy, Method method, Object[] args,
			MethodProxy methodProxy) throws Throwable {
		personServiceBean bean =(personServiceBean) this.targetObject;
		Object result = null;
		if(bean.getUser()!=null){
			//advice -->AOP术语：前置通知
			 try {
				result = methodProxy.invoke(targetObject, args);
				//afteradvice-->AOP术语：后置通知
			} catch (Exception e) {
				//Exceptionadvice-->AOP术语：例外通知
			}finally{
				//finallyadvice-->AOP术语：最终通知
			}
		}
		return result;
	}
}

package cn.itcast.service.aop;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import cn.itcast.service.impl.personServiceBean2;
public class JDKProxyFactory implements InvocationHandler{
	private Object targetObject;
	public Object createProxyIntance(Object targetObject){
		this.targetObject =targetObject;
		return Proxy.newProxyInstance(this.targetObject.getClass().getClassLoader()
					, this.targetObject.getClass().getInterfaces(), this);
	}
	public Object invoke(Object arg0, Method arg1, Object[] arg2)
			throws Throwable {
		personServiceBean2 bean =(personServiceBean2) this.targetObject;
		Object result = null;
		if(bean.getUser()!=null){
			 result = arg1.invoke(targetObject, arg2);
		}
		return result;
	}
}

代码三：personServiceBean.java和personServiceBean2.java

package cn.itcast.service.impl;
import cn.itcast.service.IPersonService;
public class personServiceBean  {
	private String user ;

	public String getUser() {
		return user;
	}
	public personServiceBean() {
	}

	public personServiceBean(String user) {
		this.user = user;
	}

	public String getPersonName(Integer personId) {
		return "postino";
	}

	public void save(String name) {
		System.out.println("这是save方法");
	}
}

package cn.itcast.service.impl;
import cn.itcast.service.IPersonService;
public class personServiceBean2 implements IPersonService {
	private String user ;
	public String getUser() {
		return user;
	}
	public personServiceBean2() {
	}
	public personServiceBean2(String user) {
		this.user = user;
	}
	public String getPersonName(Integer personId) {
		return "postino";
	}
	public void save(String name) {
		System.out.println("这是save方法");
	}
	public void update(String name, Integer personId) {
		System.out.println("这是update方法");
	}
}

测试类：AOPTest.java

package junit.test;
import static org.junit.Assert.*;
import org.junit.BeforeClass;
import org.junit.Test;
import cn.itcast.service.aop.CGlibProxyFactory;
import cn.itcast.service.aop.JDKProxyFactory;
import cn.itcast.service.impl.personServiceBean;
import cn.itcast.service.impl.personServiceBean2;
import cn.itcast.service.IPersonService;
public class AOPTest {
	@BeforeClass
	public static void setUpBeforeClass() throws Exception {
	}
	@Test public void proxyTest(){
		JDKProxyFactory jdkpf = new JDKProxyFactory();
		IPersonService ipersonService = (IPersonService)jdkpf.createProxyIntance(new personServiceBean2(""));
		ipersonService.save("");
	}
	@Test public void proxyTest2(){
		CGlibProxyFactory jdkpf = new CGlibProxyFactory();
		personServiceBean service = (personServiceBean)jdkpf.createProxyIntance(new personServiceBean(""));
		service.save("");
	}
}

学习总结：
1:JDKProxy拦截是，通过新建一个Proxy对象来实现的，里面传入三个参数，一个目标类的类加载器，一个目标类实现了的接口，一个目标类对象Proxy.newProxyInstance(this.targetObject.getClass().getClassLoader() , this.targetObject.getClass().getInterfaces(), this);

2：CGlib是通过定义Enhancer类的对象，然后覆盖目标类的非final方法实现的集成，在通过回调

3：如果是用JDKProxy实现拦截，那么目标类必须是面向接口编程。而CGlib则不需要