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 {

    @Override
    public 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;
    }

    @Override
    public 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 [1846080280@qq.com]
 * @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/beans
       			   http://www.springframework.org/schema/beans/spring-beans.xsd
       			   http://www.springframework.org/schema/aop
       			   http://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：