Spring 学习笔记（7）

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Spring 的 AOP 基于 AspectJ 注解开发开发步骤

•         引入jar包
  
•         设置配置文件：
  

<?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"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/aop
http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/tx
http://www.springframework.org/schema/tx/spring-tx.xsd">
</beans>

•         编写配置目标类
  

<bean id="orderDao" class="demo1.OrderDao"></bean>
public class OrderDao {
public void save(){
System.out.println("save order");
}
public void update(){
System.out.println("update order");
}
public void delete(){
System.out.println("delete order");
}
public void find(){
System.out.println("find order");
}
}

•         开启aop注解自动代理
  

<aop:aspectj-autoproxy/>

•         编写切面类并配置
  

@Aspect
public class MyAspectAnno {
@Before(value="execution(* demo1.OrderDao.save(..))")
public void before(){
System.out.println("before");
}
}
<bean id="myAspect" class="demo1.MyAspectAnno">
注解通知类型

•         @Before： 前置通知
  
•         @AfterReturning: 后置通知
  

@AfterReturning(value="execution(* demo1.OrderDao.save(..))",returning="result")
public void after(Object result){
System.out.println("after "+result);
}

•         @Around：环绕通知
  

@Around(value="execution(* demo1.OrderDao.save(..))")
public Object around(ProceedingJoinPoint joinPoint) throws Throwable{
System.out.println("before");
Object obj=joinPoint.proceed();
System.out.println("after");
return obj;
}

•         @AfterThrowing: 抛出异常
  

@AfterThrowing(value="execution(* demo1.OrderDao.save(..))",throwing="e")
public void afterThrowing(Throwable e){
System.out.println("exception:"+e.getMessage();
}

•         @After: 最终通知
  

@After(value="execution(* demo1.OrderDao.save(..))")
public void after(){
System.out.println("finally");
}

•         @PointCut:切入点注解
  

@PointCut(value="execution(* demo1.OrderDao.save(..))")
private void pointcut1(){}
此时，在上述通知的注解中，value可以替换为该函数名，例如：
@After(value="MyAspect.pointcut1()")
public void after(){
System.out.println("finally");
}
这个注解的好处是，只需要维护切入点即可，不用在修改时修改每个注解。