Spring -- 基于注解的AOP开发

Posted 2021-12-05 CodeJiao

01：Spring – AOP简介
02：Spring – 基于XML的AOP开发
03：Spring – 基于注解的AOP开发

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1. 快速入门

只要明白了基于XML的AOP开发，那么基于注解就很简单。

开发步骤：

准备工作：导入相关依赖

pom.xml

<?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">
    <parent>
        <artifactId>spring_study</artifactId>
        <groupId>com.tian</groupId>
        <version>1.0-SNAPSHOT</version>
    </parent>
    <modelVersion>4.0.0</modelVersion>

    <artifactId>spring_aop</artifactId>
    <dependencies>
        <!--        Spring依赖-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>5.0.5.RELEASE</version>
        </dependency>
        <!--        aop织入依赖-->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.8.4</version>
        </dependency>
        <!--        spring-test依赖-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>5.0.5.RELEASE</version>
        </dependency>
        <!--        junit单元测试-->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.13.2</version>
        </dependency>
    </dependencies>
    <properties>
        <maven.compiler.source>8</maven.compiler.source>
        <maven.compiler.target>8</maven.compiler.target>
    </properties>
</project>

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示例代码：

TargetInterface.java

package com.tian.anno;

public interface TargetInterface {
    public void save();
}

Target.java

package com.tian.anno;

import org.springframework.stereotype.Component;

@Component("target")
public class Target implements TargetInterface {
    public void save() {
        System.out.println("save running.....");
    }
}

MyAspect.java

package com.tian.anno;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.*;
import org.springframework.stereotype.Component;

@Component("myAspect")
@Aspect //标注当前MyAspect是一个切面类
public class MyAspect {

    //配置前置通知 
    @Before("execution(* com.tian.anno.*.*(..))")
    public void before() {
        System.out.println("前置增强..........");
    }

    @After("execution(* com.tian.anno.*.*(..))")
    public void afterReturning() {
        System.out.println("后置增强..........");
    }

    //Proceeding JoinPoint:  切点
//    @Around("execution(* com.tian.anno.*.*(..))")
    @Around("pointcut()")
    public Object around(ProceedingJoinPoint pjp) throws Throwable {
        System.out.println("环绕前增强....");
        Object proceed = pjp.proceed();//切点方法
        System.out.println("环绕后增强....");
        return proceed;
    }

    @AfterThrowing("MyAspect.pointcut()")
    public void afterThrowing() {
        System.out.println("异常抛出增强..........");
    }

    @After("MyAspect.pointcut()")
    public void after() {
        System.out.println("最终增强..........");
    }

    //定义切点表达式
    @Pointcut("execution(* com.tian.anno.*.*(..))")
    public void pointcut() {
    }
}

配置文件：

applicationContext.xml

配置组件扫描和aop自动代理即可

<?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">
    <!--组件扫描-->
    <context:component-scan base-package="com.tian.anno"/>
    <!--aop自动代理-->
    <aop:aspectj-autoproxy/>
</beans>

测试代码：

AnnoTest.java

package test;

import com.tian.anno.TargetInterface;
import org.junit.Test;
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:applicationContext.xml")
public class AnnoTest {

    @Autowired
    private TargetInterface target;

    @Test
    public void test1() {
        target.save();
    }
}

运行结果：

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2. 注解配置AOP详解

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2.1 注解通知的类型

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2.2 切点表达式的抽取

同xml配置 aop一样，我们可以将切点表达式抽取。抽取方式是在切面内定义方法，在该方法上使用@Pointcut注解定义切点表达式，然后在在增强注解中进行引用。具体如下:

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3. 小结

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