一、spring对AOP的支持(在JDK动态代理和CGLIB之间的选择)
1、如果目标对象实现了接口,默认情况下会采用JDK的动态代理实现AOP
2、如果目标对象实现了接口,可以强制使用CGLIB实现AOP
3、如果目标对象没有实现了接口,必须采用CGLIB库,
4、如果有些实现有些没有实现,spring会自动在JDK动态代理和CGLIB之间转换
如何强制使用CGLIB实现AOP?
* 添加CGLIB库,SPRING_HOME/cglib/*.jar
* 在spring配置文件中加入<aop:aspectj-autoproxy proxy-target-class="true"/>
JDK动态代理和CGLIB字节码生成的区别?
* JDK动态代理只能对实现了接口的类生成代理,而不能针对类
* CGLIB是针对类实现代理,主要是对指定的类生成一个子类,覆盖其中的方法
因为是继承,所以该类或方法最好不要声明成final
二、原程序
package com.bjsxt.spring; public class UserManagerImpl { // implements UserManager { public void addUser(String username, String password) { System.out.println("-------UserManagerImpl.addUser()----------"); } public void deleteUser(int id) { System.out.println("-------UserManagerImpl.deleteUser()----------"); } public String findUserById(int id) { System.out.println("-------UserManagerImpl.findUserById()----------"); return null; } public void modifyUser(int id, String username, String password) { System.out.println("-------UserManagerImpl.modifyUser()----------"); } }
package com.bjsxt.spring; import org.aspectj.lang.JoinPoint; public class SecurityHandler { private void checkSecurity(JoinPoint joinPoint) { Object[] args = joinPoint.getArgs(); for (int i=0; i<args.length; i++) { System.out.println(args[i]); } System.out.println(joinPoint.getSignature().getName()); System.out.println("----------checkSecurity()---------------"); } }
package com.bjsxt.spring; import org.springframework.beans.factory.BeanFactory; import org.springframework.context.support.ClassPathXmlApplicationContext; public class Client { public static void main(String[] args) { BeanFactory factory = new ClassPathXmlApplicationContext("applicationContext.xml"); UserManagerImpl userManager = (UserManagerImpl)factory.getBean("userManager"); userManager.addUser("张三", "123"); } }
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.0.xsd"> <!-- <aop:aspectj-autoproxy proxy-target-class="true"/> --> <bean id="securityHandler" class="com.bjsxt.spring.SecurityHandler"/> <bean id="userManager" class="com.bjsxt.spring.UserManagerImpl"/> <aop:config> <aop:aspect id="security" ref="securityHandler"> <aop:pointcut id="allAddMethod" expression="execution(* com.bjsxt.spring.UserManagerImpl.add*(..))"/> <aop:before method="checkSecurity" pointcut-ref="allAddMethod"/> </aop:aspect> </aop:config> </beans>