Spring AOP 复习

骑猪看日落 2022-10-08 02:24 145阅读 0赞

个人理解：可以分离代码，降低方法耦合度，增强方法功能

# 一、注解方式 #

package com.sunj.dao;
    
    import org.springframework.stereotype.Repository;
    
    @Repository("userDao2")
    public class UserDao {
        public void add(){
            System.out.println("flag= "+ this.flag);
            System.out.println("添加方法1");
        }
    
        private boolean flag;
    
        public void setFlag(boolean flag) {
            System.out.println("注解构造bean");
            this.flag = flag;
        }
    
    }

package com.sunj.service;
    
    import com.sunj.dao.UserDao;
    import org.springframework.beans.factory.annotation.Autowired;
    import org.springframework.stereotype.Service;
    
    @Service
    public class UserService {
    
        @Autowired
    //    @Resource(name = "userDao")
        private UserDao userDao1;
    
        public void add(){
    //        int i = 1/0;
            System.out.println("service方法");
            userDao1.add();
        }
    }

package com.sunj.aop;
    
    import org.aspectj.lang.ProceedingJoinPoint;
    import org.aspectj.lang.annotation.*;
    import org.springframework.stereotype.Component;
    
    @Component  //该注解把类实例化到spring容器中
    @Aspect
    public class TransactionAop {
    
    
        @Before("execution(* com.sunj.service.UserService.add(..))")
        public void  begin(){
            System.out.println("前置通知");
        }
    
        @After("execution(* com.sunj.service.UserService.add(..))")
        public void end(){
            System.out.println("后置通知");
        }
    
        @Around("execution(* com.sunj.service.UserService.add(..))")
        public void around(ProceedingJoinPoint joinPoint) throws Throwable {
            System.out.println("环绕处理之前");
            joinPoint.proceed();
            System.out.println("环绕处理之后");
        }
    
    
        /*
        该方法在位切面方法未遇到错误时不会执行
         */
        @AfterThrowing("execution(* com.sunj.service.UserService.add(..))")
        public void meetException() throws Throwable {
            System.out.println("异常通知");
        }
    
    
    //    @AfterReturning("execution(* com.sunj.service.UserService.add(..))")
    //    public void returnNo() throws Throwable {
    //        System.out.println("返回通知");
    //    }
    
    
    
    
    }

package com.sunj.entity;
    
    import com.sunj.UserController;
    import com.sunj.service.UserService;
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    import org.springframework.stereotype.Controller;
    
    public class Test3 {
        public static void main(String[] args) {
    
            ApplicationContext applicationContext =new ClassPathXmlApplicationContext("applicationContext2.xml");
            UserService userService = (UserService) applicationContext.getBean("userService");
            userService.add();
        }
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1N1bl9vZl9SYWlueQ_size_16_color_FFFFFF_t_70][]

1、首先需要在xml开启aop注解

![20210619173626659.png][]

2、各注解讲解

1）、@Component   该注解把类实例化到spring容器中

2）、@Aspect， 表示切面

3）、 @Before ，切入点方法之前执行

4）、@After, 切入点方法之后执行

5）、@around，比@Before和@After都晚

6）、@AfterThrowing，切入点方法报错时会执行，不报错则不执行

# 二、xml方式 #

1、背景：去掉@Component之后， aop的切面类就不能注入到ioc容器中，所以切面则不会起作用

2、采用xml配置解决

<?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:p="http://www.springframework.org/schema/p"
           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.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">
    
        <context:component-scan base-package="com.sunj"></context:component-scan>
        <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
        <bean id="transactionAop" class="com.sunj.aop.TransactionAop"></bean>  
        <aop:config>
            <aop:pointcut expression="execution(* com.sunj.service.UserService.add(..))" id="pt" /> 
            <aop:aspect ref="transactionAop">
                <aop:around method="around" pointcut-ref="pt"/>      
                <aop:after-throwing method="meetException" pointcut-ref="pt"/>
                <aop:before method="begin" pointcut-ref="pt"/>
                <aop:after method="end" pointcut-ref="pt"/>
            </aop:aspect>
    
    
        </aop:config>
    
    
    </beans>

package com.sunj.aop;
    
    import org.aspectj.lang.ProceedingJoinPoint;
    import org.aspectj.lang.annotation.*;
    import org.springframework.stereotype.Component;
    
    //@Component  //该注解把类实例化到spring容器中
    @Aspect
    public class TransactionAop {
    
    
    //    @Before("execution(* com.sunj.service.UserService.add(..))")
        public void  begin(){
            System.out.println("前置通知");
        }
    
    //    @After("execution(* com.sunj.service.UserService.add(..))")
        public void end(){
            System.out.println("后置通知");
        }
    
    //    @Around("execution(* com.sunj.service.UserService.add(..))")
        public void around(ProceedingJoinPoint joinPoint) throws Throwable {
            System.out.println("环绕处理之前");
            joinPoint.proceed();
            System.out.println("环绕处理之后");
        }
    
    
        /*
        该方法在位切面方法未遇到错误时不会执行
         */
    //    @AfterThrowing("execution(* com.sunj.service.UserService.add(..))")
        public void meetException() throws Throwable {
            System.out.println("异常通知");
        }
    
    
    }

[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L1N1bl9vZl9SYWlueQ_size_16_color_FFFFFF_t_70]: /images/20221005/375a84372d63413db79070827c90e327.png
[20210619173626659.png]: /images/20221005/5f655a382fde4d34be138fc75b10df57.png