1：aop:面向切面编程

aop术语：

Joinpoint 连接点：原对象的方法

Pointcut 切入点：代理中已增强的方法

Advice 通知增强：增强的代码

Target 目标对象：被代理的对象，原对象

Waving 织入：通知应用到切入点的过程

proxy 代理：织入目标对象后，形成代理对象

aspect 切面：切入点+通知。通常为切面类

通知对象：

前置通知 before：目标方法之前加的代码

后置通知 After：目标方法之后加的代码。无论是否出现异常都会调用。相当于python异常try代码块中的finally

后置返回通知 AfterRetruning：目标方法之后的代码。出现异常不调用。相当于python异常try代码块中的else

环绕通知 AroundReturning ：在目标方法的前后调用

异常通知 After：在目标方法出现异常后调用

2：底层为代理模式

代理模式详见以前文章: 代理模式  https://blog.csdn.net/xinyuebaihe/article/details/104202951

3：使用：

分为配置方式与注解方式

示例目录结构

目录结构

lib

1）用配置方式

切面

package com.csdn.advice;import org.aspectj.lang.ProceedingJoinPoint;
import org.springframework.stereotype.Component;@Component
public class MyAdvice {public void before() throws Throwable {System.out.println("这是前置通知");}public void after(){System.out.println("这是后置通知");}public void afterReturning(){System.out.println("这是没有异常的后置通知，相当于python中的else");}public void exception(){System.out.println("这是发生异常后的通知");}/*** 增强版的环绕通知。强大无比，可以替代其它通知* @param jp* @throws Throwable*/public void around2(ProceedingJoinPoint jp) throws Throwable {System.out.println("这是环绕通知前");try{//前置通知this.before();jp.proceed();}catch (Exception e){//异常通知this.exception();}finally {//后置通知this.after();}//无异常后置通知this.afterReturning();System.out.println("这是环绕通知后");}
}

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"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.csdn.*"/><!--切面类，通知对象的bean--><bean id = "myAdvice" class="com.csdn.advice.MyAdvice"/><!--切面配置--><aop:config><!--切入点定义，目标方法，要增强哪些方法--><!--第一个星号：返回值。第二个星号：匹配的实现类。第三个星号：任意方法。两个点：方法的属性--><aop:pointcut id="pointcut" expression="execution(* com.csdn.service.impl.*ServiceImpl.*(..))"/><!--切面引入--><aop:aspect ref = "myAdvice"><!--不同类型的通知--><aop:before method="before" pointcut-ref="pointcut"/><aop:after method="after" pointcut-ref="pointcut"/><aop:after-returning method="afterReturning" pointcut-ref="pointcut"/><aop:after-throwing method="exception" pointcut-ref="pointcut"/><aop:around method="around2" pointcut-ref="pointcut"/></aop:aspect></aop:config><bean id="queryRunner" class="org.apache.commons.dbutils.QueryRunner"><constructor-arg name="ds" ref="dataSource"/></bean><context:property-placeholder location="classpath*:db.properties"/><bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"><property name="driverClass" value="${db.driver}"/><property name="jdbcUrl" value="${db.url}"/><property name="user" value="${db.username}"/><property name="password" value="${db.password}"/></bean>
</beans>

测试类

package com.csdn.test;import com.csdn.pojo.Student;
import com.csdn.service.StudentService;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;import java.sql.SQLException;
import java.util.List;@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:spring.xml")
public class Test {@Autowiredprivate StudentService studentService;@org.junit.Testpublic void test01(){
//        List<Student> all = null;
//        try {
//            all = studentService.findAll();
//
//        } catch (SQLException e) {
//            e.printStackTrace();
//        }
//        System.out.println(all);studentService.add();}
}

2）用注解方式

切面

<?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.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"><!--包扫描。会生成bean--><context:component-scan base-package="com.csdn.*"/><!--配置自动切面生成。一定要有，要不然只有切面类注解也无效--><aop:aspectj-autoproxy/><bean id="queryRunner" class="org.apache.commons.dbutils.QueryRunner"><constructor-arg name="ds" ref="dataSource"/></bean><context:property-placeholder location="classpath*:db.properties"/><bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"><property name="driverClass" value="${db.driver}"/><property name="jdbcUrl" value="${db.url}"/><property name="user" value="${db.username}"/><property name="password" value="${db.password}"/></bean>
</beans>

配置文件

package com.csdn.advice;import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.stereotype.Component;@Component
@Aspect
public class MyAdvice2 {@Pointcut("execution(* com.csdn.service.impl.*ServiceImpl2.*(..))")public void pointcut(){}@Before("MyAdvice2.pointcut()")public void before() throws Throwable {System.out.println("这是前置通知");}@After("MyAdvice2.pointcut()")public void after(){System.out.println("这是后置通知");}@AfterReturning("MyAdvice2.pointcut()")public void afterReturning(){System.out.println("这是没有异常的后置通知，相当于python中的else");}@AfterThrowing("MyAdvice2.pointcut()")public void exception(){System.out.println("这是发生异常后的通知");}/*** 增强版的环绕通知。强大无比，可以替代其它通知* @param jp* @throws Throwable*/@Around("MyAdvice2.pointcut()")public void around2(ProceedingJoinPoint jp) throws Throwable {System.out.println("这是环绕通知前");try{//前置通知this.before();jp.proceed();}catch (Exception e){//异常通知this.exception();}finally {//后置通知this.after();}//无异常后置通知this.afterReturning();System.out.println("这是环绕通知后");}}

测试类

package com.csdn.test;import com.csdn.service.StudentService;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:spring2.xml")
public class Test2 {@Autowired()private StudentService studentService2;@org.junit.Testpublic void test01(){
//        List<Student> all = null;
//        try {
//            all = studentService.findAll();
//
//        } catch (SQLException e) {
//            e.printStackTrace();
//        }
//        System.out.println(all);studentService2.add();}
}