AOP(面向切面编程)基于XML方式配置

 概念解释：（理解基本概念方可快速入手）

1. 连接点（joinpoint）

   被拦截到的点，因为Spring只支持方法类型的连接点，所以在Spring中连接点指的就是被拦截到的方法。

2. 切入点（pointcut）

   切入点是指我们要对哪些连接点进行拦截的定义

3. 通知（advice）

   所谓通知指的就是指拦截到连接点之后要执行的代码，通知分为前置、后置、异常、最终、环绕通知五类

4. 切面（aspect）

   是切入点和通知的结合

 通知顺序：

前置通知：aop:before
            后置通知：aop:after-returning【try】
            最终通知：aop:after【finally】
            异常通知：aop:after-throwing【catch】
            环绕通知：aop:around

            try{
                ...
                return aop:after-returning
            }catch(Exception e){
                ...
                aop:after-throwing
            }finally{
                ...
                aop:after
            }

切点表达式：
        格式：execution([修饰符] 返回值 报名.类名.方法名(参数))
        eg：execution(* com.by.service.*.*(..))

 实例演示：

pom.xml:

<dependencies><!--ioc--><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>6.0.12</version></dependency><!--支持切点表达式AOP --><dependency><groupId>org.springframework</groupId><artifactId>spring-aspects</artifactId><version>5.1.8.RELEASE</version></dependency><dependency><groupId>org.slf4j</groupId><artifactId>slf4j-log4j12</artifactId><version>1.7.19</version></dependency></dependencies>

UserDaoImpl:

package com.by.dao;public class UserDaoImpl implements UserDao {@Overridepublic void addUser(){System.out.println("insert into tb_user......");}
}

UserServiceImpl:

package com.by.service;import com.by.dao.UserDao;public class UserServiceImpl implements UserService {private UserDao userDao;public void setUserDao(UserDao userDao) {this.userDao = userDao;}@Overridepublic void addUser(){userDao.addUser();System.out.println(8/0);}
}

MyLogActive:(增强类)

/** Copyright (c) 2020, 2024,  All rights reserved.**/
package com.by.advice;import org.aspectj.lang.ProceedingJoinPoint;/*** <p>Project: Spring - MyLogAdvice</p>* <p>Powered by scl On 2024-01-05 15:04:11</p>* <p>描述：<p>** @author 孙臣龙 [[e-mail]]* @version 1.0* @since 17*/
public class MyLogAdvice {public void after() {System.out.println("最终通知、、、");}public void before() {System.out.println("前置通知、。、");}public void afterReturn(){System.out.println("后置通知");}public void afterThrowing(){System.out.println("异常通知");}public void around(ProceedingJoinPoint joinPoint) {try {System.out.println("前环绕通知。。。");joinPoint.proceed();System.out.println("后环绕通知。。。");} catch (Throwable e) {throw new RuntimeException(e);}}
}

 applicationContext.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!--注意：添加约束-->
<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"xsi:schemaLocation="http://www.springframework.org/schema/beanshttp://www.springframework.org/schema/beans/spring-beans.xsdhttp://www.springframework.org/schema/aophttp://www.springframework.org/schema/aop/spring-aop.xsd"><bean id="userDao" class="com.by.dao.UserDaoImpl"></bean><bean id="userService" class="com.by.service.UserServiceImpl"><property name="userDao" ref="userDao"></property></bean><!--增强--><bean id="myLogAdvice" class="com.by.advice.MyLogAdvice"></bean><!--aop--><aop:config><!--切点--><aop:pointcut id="pointcut" expression="execution(* com.by.service.*.*(..))"/><!--切面--><aop:aspect ref="myLogAdvice"><aop:before method="before" pointcut-ref="pointcut"></aop:before><aop:after method="after" pointcut-ref="pointcut"></aop:after><aop:around method="around" pointcut-ref="pointcut"></aop:around><aop:after-returning method="afterReturn" pointcut-ref="pointcut"></aop:after-returning><aop:after-throwing method="afterThrowing" pointcut-ref="pointcut"></aop:after-throwing></aop:aspect></aop:config></beans>

没增强前结果展示：

增强之后结果展示：