使用AspectJ来产生动态代理
AOP的实现者:
AspectJ , AspectWerkz, JBoss AOP, Spring AOP.
在Spring2.0中,Spring AOP , IoC和AspectJ整合到一起了。
要理解AOP就必须要先知道动态代理,Spring AOP底层使用了两种代理机制:一种是基于JDK的动态代理;一种是基于CGLib的动态代理。之所以要有两种代理机制,很大程度上是因为JDK本身只提供接口的代理,而不支持类的代理。
看api理解那几个专业名词
下面就是一个AspectJ产生代理的一个例子
先要让程序支持AspectJ,看bean.xml文件的配置
<?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:context="http://www.springframework.org/schema/context" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd"> <context:annotation-config /> <context:component-scan base-package="com.lbx"/> <aop:aspectj-autoproxy /> </beans>
需要在目标类中方法执行前加入的处理(相当于拦截器)@AspectJ
注意:一定要加@Componnent
package com.lbx.aop; import org.aspectj.lang.annotation.Aspect; import org.aspectj.lang.annotation.Before; import org.springframework.stereotype.Component; @Aspect @Component public class LogInterceptor { @Before("execution(public void com.lbx.dao.impl.UserDaoImpl.add(com.lbx.po.User))") public void before(){ System.out.println("LogInterceptor.before()");; } }
其他的类
package com.lbx.service.impl; import javax.annotation.Resource; import org.springframework.stereotype.Component; import com.lbx.dao.UserDao; import com.lbx.po.User; import com.lbx.service.UserService; @Component("userService") public class UserServiceImpl implements UserService { private UserDao userDao; public void add(User user) { userDao.add(user); } public UserDao getUserDao() { return userDao; } @Resource(name="userDao") //最好用@Resource 不要用@Autowired public void setUserDao( UserDao userDao) { this.userDao = userDao; } }
package com.lbx.dao.impl; import org.springframework.stereotype.Component; import com.lbx.dao.UserDao; import com.lbx.po.User; @Component("userDao") //UserDaoImpl public class UserDaoImpl implements UserDao { public void add(User user) { // TODO Auto-generated method stub System.out.println("一个user添加进来"); } }