1.Spring AOP简介

AOP (Aspect Oriented Programming)面向切面编程
OOP(Oriented Oriented Programming)面向对象编程
通过OOP的纵向和AOP的横向抽取，程序才可以真正解决问题
AOP的使用场景:日志事务

2.AOP的核心概念

Aspect（切面）
Join Point（连接点）
Advice（通知/增强）
Pointcut（切点）
Introduction（引入）
Target Object（目标对象）
AOP Proxy（AOP代理）
Weaving（织入）

3.HelloWorld前置增强练习

给pom文件中添加aop依赖

 <!--spring-aop依赖-->
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-aop</artifactId>
      <version>${spring.version}</version>
    </dependency>
    <!--aspectj依赖-->
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjrt</artifactId>
      <version>${aspectj.version}</version>
    </dependency>
    <dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
      <version>${aspectj.version}</version>
    </dependency>

Hello接口类

package com.spring.aop;
public interface Hello {
    String getHello();
}

HelloImpl类

package com.spring.aop;
public class HelloImpl implements Hello {
    @Override
    public String getHello() {
        return "Hello,Spring AOP";
    }
}

用户自定义的前置增强类MyBeforeAdvicelei

package com.spring.aop;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/*
 * 用户自定义的前置增强类
 * */
public class MyBeforeAdvice {
    private  static final Logger logger= LoggerFactory.getLogger(MyBeforeAdvice.class);
    /*定义前置方法*/
    public void beforeMethod() {
        logger.info("This is a before method by wxy");
        logger.debug("This is a before method by wxy");
      //System.out.println("This is a before methoad");
    }
}

用日志记录方法

配置文件

     <!--配置一个Hello的bean  等同于Hello hello = new HelloImpl();-->
     <bean id="hello" class="com.spring.HelloImpl"/>
      <!--配置一个MyBeforeAdvice前置增强的bean-->
      <bean id="mybeforeAdvice" class="com.spring.MyBeforeAdvice"/>
    <!--配置Aop-->
    <aop:config>
        <aop:aspect id="before" ref="mybeforeAdvice">
            <aop:pointcut id="myPointcut" expression="execution(* com.spring.aop.*.*(..))"/>
            <aop:before method="beforeMethod" pointcut-ref="myPointcut"/>
        </aop:aspect>
    </aop:config>

HelloApp主类

package com.spring.aop;
import javafx.application.Application;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class HelloApp {
    public static void main(String[] args) {
        ApplicationContext context = new ClassPathXmlApplicationContext("/bean.xml");
        Hello hello = context .getBean(Hello.class);
        System.out.println(hello.getHello());
    }
}