简述SpringAOP的实现原理_spring AOP

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发布于 2022-09-21 08:40:24

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发布于 2022-09-21 08:40:24

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AOP

用Spring需要导入包

<dependency>
      <groupId>org.aspectj</groupId>
      <artifactId>aspectjweaver</artifactId>
      <version>1.9.4</version>  
</dependency>

方式一：使用Spring接口

编写java

package com.kuang.log;

import org.springframework.aop.MethodBeforeAdvice;

import java.lang.reflect.Method;

public class Log implements MethodBeforeAdvice { 
   
    //method 要执行的目标对象的方法
    //args 参数
    //target 目标对象
    public void before(Method method, Object[] args, Object target) throws Throwable { 
   
        System.out.println(target.getClass().getName() + "的" + method.getName() + "被执行了");
    }
}

package com.kuang.log;

import org.aspectj.lang.annotation.AfterReturning;
import org.springframework.aop.AfterReturningAdvice;

import java.lang.reflect.Method;

public class AfterLog implements AfterReturningAdvice { 
   

    public void afterReturning(Object returnValue, Method method, Object[] args, Object target) throws Throwable { 
   
        System.out.println("执行了" + method.getName() + "返回结果为:" + returnValue);
    }
}

编写xml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 https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">
    <!--注册bean-->
    <bean id="userService" class="com.kuang.service.UserServiceImpl"/>
    <bean id="log" class="com.kuang.log.Log"/>
    <bean id="afterLog" class="com.kuang.log.AfterLog"/>

    <!--方式一：使用原声Spring API接口-->
    <!--配置opp：需要导入opp的约束-->
    <aop:config>
        <!--切入点：expression：表达式，execution(要执行的位置！* * * * *)-->
        <aop:pointcut id="pointcut" expression="execution(* com.kuang.service.UserServiceImpl.*(..))"/>

        <!--执行环绕增加-->
        <aop:advisor advice-ref="log" pointcut-ref="pointcut"/>
        <aop:advisor advice-ref="afterLog" pointcut-ref="pointcut"/>
    </aop:config>
</beans>

编写测试类

import com.kuang.pojo.User;
import com.kuang.service.UserService;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Mytest  { 
   
    public static void main(String[] args) { 
   
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");

        UserService userService = (UserService)context.getBean("userService");
        userService.add();
    }
}

方式二：使用自定义类来实现AOP

package com.kuang.diy;

public class DiyPointCut { 
   
    public void before(){ 
   
        System.out.println("===========方法执行前==========");
    }

    public void after(){ 
   
        System.out.println("===========方法执行后==========");
    }

}

xml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 https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--方式二：自定义类-->
    <bean id="diy" class="com.kuang.diy.DiyPointCut"/>
    <aop:config>
        <!--自定义切面，ref要引用的类-->
        <aop:aspect ref="diy">
            <!--切入点-->
            <aop:pointcut id="point" expression="execution(* com.kuang.service.UserServiceImpl.*())"/>
            <!--通知-->
            <aop:before method="before" pointcut-ref="point"/>
            <aop:after method="after" pointcut-ref="point"/>
        </aop:aspect>
    </aop:config>
</beans>

测试

import com.kuang.pojo.User;
import com.kuang.service.UserService;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Mytest  { 
   
    public static void main(String[] args) { 
   
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");

        UserService userService = (UserService)context.getBean("userService");
        userService.add();
    }
}

方式三：使用注解实现 xml配置

<?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 https://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop.xsd">
    <!--注册bean-->
    <bean id="userService" class="com.kuang.service.UserServiceImpl"/>

    <bean id="diy" class="com.kuang.diy.DiyPointCut"/>
    <!--方式三：自定义类-->
    <!--开启注解支持-->
    <aop:aspectj-autoproxy/>
</beans>

package com.kuang.diy;

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.Signature;
import org.aspectj.lang.annotation.After;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;

@Aspect
public class DiyPointCut { 
   
    @Before("execution(* com.kuang.service.UserServiceImpl.*(..))")
    public void before(){ 
   
        System.out.println("===========方法执行前==========");
    }
    @After("execution(* com.kuang.service.UserServiceImpl.*(..))")
    public void after(){ 
   
        System.out.println("===========方法执行后==========");
    }
    //在环绕增强中，我们可以传入一个参数，代表我们要获取处理切入的点
    @Around("execution(* com.kuang.service.UserServiceImpl.*(..))")
    public void around(ProceedingJoinPoint jp) throws Throwable { 
   
        System.out.println("环绕前");

        Signature signature = jp.getSignature();//获得签名
        System.out.println("signature:" + signature);

        Object proceed = jp.proceed();
        System.out.println("环绕后");

    }

}

测试

import com.kuang.pojo.User;
import com.kuang.service.UserService;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Mytest  { 
   
    public static void main(String[] args) { 
   
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("beans.xml");

        UserService userService = (UserService)context.getBean("userService");
        userService.add();
    }
}