Spring-AOP

• 概念：AOP(Aspect Oriented Programming)面向切面编程，一种编程范式，指导开发者如何组织程序结构
  • OOP(Object Oriented Programming) 面向对象编程
• 作用：在不惊动原有设计的基础上为其进行功能增强
• Spring理念：无入侵式/无侵入式

1.入门案例

1.1 模拟业务执行一万次

package com.ttc.dao.impl;import com.ttc.dao.BookDao;
import org.springframework.stereotype.Repository;@Repository
public class BookDaoImpl implements BookDao{public void save(){Long startTime = System.currentTimeMillis();for(int i=0;i<10000;i++){System.out.println("book dao save");}Long endTime = System.currentTimeMillis();System.out.println("业务执行万次所需时间：" + (endTime - startTime));         }public void select(){System.out.println("book dao select");}public void delete(){System.out.println("book dao delete");}public void update(){System.out.println("book dao update");}}

package com.ttc.aop;public class MyAdvice{public void method(){Long startTime = System.currentTimeMillis();for(int i=0;i<10000;i++){// 调用原始操作}Long endTime = System.currentTimeMills();System.out.println("业务执行万次所需时间：" + (endTime - startTime));}
}

1.2 AOP核心概念

• 连接点(JoinPoint)：原始方法是连接点
• 切入点(PointCut)：需要追加功能的方法是切入点
• 通知(Advice)：MyAdvice类中的method方法
• 切面(Aspect)：切面就是描述在哪个切入点上执行哪些通知

1.3 坐标导入

• 导入spring-context的坐标包含了spring-aop
• 导入aspect的坐标

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>com.ttc</groupId><artifactId>aop-demo</artifactId><version>1.0-SNAPSHOT</version><dependencies><dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId><version>5.2.10.RELEASE</version></dependency><!-- 导入aspect坐标 --><dependency><groupId>org.aspectj</groupId><artifactId>aspectjweaver</artifactId><version>1.9.4</version></dependency></dependencies>
</project>

1.4 aop初体验

1. 制作MyAdvice

package com.ttc.aop;import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.stereotype.Component;@Component
@Aspect
public class MyAdvice {// 描述切入点@Pointcut("execution (void com.ttc.dao.BookDao.update())")private void pt() {}// 在切入点之前执行通知@Before("pt()")public void method() {System.out.println(System.currentTimeMillis());}
}

2. 配置SpringConfig

package com.ttc.config;import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;@Configuration
@ComponentScan("com.ttc")
// 启用注解开发的AOP
@EnableAspectJAutoProxy
public class SpringConfig {
}

3. 启动类测试

package com.ttc;import com.ttc.config.SpringConfig;
import com.ttc.dao.BookDao;
import org.springframework.context.ApplicationContext;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;public class App {public static void main(String[] args) {ApplicationContext ctx = new AnnotationConfigApplicationContext(SpringConfig.class);BookDao bookDao = ctx.getBean(BookDao.class);bookDao.update();}
}