利用JDK提供的Proxy类和cglib.jar实现Aop功能

最新推荐文章于 2025-02-21 01:50:10 发布

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最新推荐文章于 2025-02-21 01:50:10 发布

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本文介绍了Java中使用JDK Proxy和CGLIB实现面向切面编程（AOP）的技术，详细阐述了如何通过代理类实现前置、后置、异常和最终通知，以及这两种实现方式之间的区别。

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1、利用Proxy实现用户权限控制；
接口类

package cn.ts.service;

public interface PersonService {
	public void save(String name);
	public void update(String name, Integer personid);
	public String getPersonName(Integer personid);
	
}

实现接口类：
package cn.ts.service;

import cn.ts.service.PersonService;

public class PersonServiceBean implements PersonService{
	private String user = null;
	
	public String getUser() {
		return user;
	}

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

	public String getPersonName(Integer personid) {
		System.out.println("我是getPersonName()方法");
		return "xxx";
	}

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

	public void update(String name, Integer personid) {
		System.out.println("我是update()方法");
	}

}

Proxy实现的代理类：
package cn.ts.aop;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

import cn.ts.service.PersonServiceBean;

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 proxy, Method method, Object[] args)
			throws Throwable {//环绕通知
		PersonServiceBean bean = (PersonServiceBean) this.targetObject;
		Object result = null; 
		if(bean.getUser()!=null){
			//..... advice()-->前置通知
			try {
				result = method.invoke(targetObject, args);
				// afteradvice() -->后置通知
			} catch (RuntimeException e) {
				//exceptionadvice()--> 例外通知
			}finally{
				//finallyadvice(); -->最终通知
			}
		}
		return result;
	}

}

cglib.jar实现的代理类：
import java.lang.reflect.Method;

import cn.ts.service.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());//非final
		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){
			result = methodProxy.invoke(targetObject, args);
		}
		return result;
	}
}

测试类：
package cn.ts.junit;


import org.junit.BeforeClass;
import org.junit.Test;


import cn.ts.aop.JDKProxyFactory;
import cn.ts.aop.cglibProxyFactory;
import cn.ts.service.PersonService;
import cn.ts.service.PersonServiceBean;

public class AOPTest {

	@BeforeClass
	public static void setUpBeforeClass() throws Exception {
	}

	@Test public void proxyTest(){
		JDKProxyFactory factory = new JDKProxyFactory();
		PersonService service = (PersonService) factory.createProxyIntance(new PersonServiceBean("xxx"));
		service.save("888");
	}
	
	@Test public void proxyTest2(){
		cglibProxyFactory factory = new cglibProxyFactory();
		PersonServiceBean service = (PersonServiceBean) factory.createProxyIntance(new PersonServiceBean("eee"));
		service.save("999");
	}
}

两种实现方式的区别在于：JDK的Proxy类的实现一个接口。cglib.jar则不定要实现某个接口；