1. AspectJ

Spirng框架一般都是基于AspectJ实现AOP操作

1.1 什么是AspectJ

AspectJ不是Spring组成部分，独立于AOP框架，一般把AsPectJ和Spring框架一起使用，进行AOP操作。

1.2 基于AspectJ实现AOP操作

1. 基于xml配置文件
2. 基于注解方式（常用）

2. Spring实现AOP

1. 引入jar包
   

2.1 基于注解

2. 创建类，在类里面定义方法

package com.spring.spring5.annotaion;

//被增强的类
public class User {
    public void add(){
        System.out.println("add......");
    }
}
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3. 创建增强类（编写增强逻辑）

在增强类里面，创建不同的方法，让不同的方法代表不同的通知类型

package com.spring.spring5.annotaion;

//增强的类
public class UserProxy {
    //前置通知
    public void before(){
        System.out.println("before......");
    }
}

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4. 进行通知的配置

• 在spring中开启注解的扫描

<?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">
    <!--开启组件扫描-->
    <context:component-scan base-package="com.spring.spring5"></context:component-scan>
</beans>
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• 使用注解创建User和UserProxy对象

package com.spring.spring5.annotaion;

import org.springframework.stereotype.Component;

//被增强的类
@Component
public class User {
    public void add(){
        System.out.println("add......");
    }
}

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package com.spring.spring5.annotaion;

import org.springframework.stereotype.Component;

//增强的类
@Component
public class UserProxy {
    //前置通知
    public void before(){
        System.out.println("before......");
    }
}

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• 在增强类的上面添加注解@Aspect

package com.spring.spring5.annotaion;

import org.aspectj.lang.annotation.Aspect;
import org.springframework.stereotype.Component;

//增强的类
@Aspect//表示生成代理对象
@Component
public class UserProxy {
    //前置通知
    public void before(){
        System.out.println("before......");
    }
}

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• 在spring配置文件中开启生成代理对象

<?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">
    <!--开启组件扫描-->
    <context:component-scan base-package="com.spring.spring5"></context:component-scan>

    <!--开启AspectJ生成代理对象-->
    <aop:aspectj-autoproxy></aop:aspectj-autoproxy>
</beans>
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5. 配置不同类型的通知

在增强类里面，在作为通知方法上面添加类型注解，使用切入点表达式配置
切入点表达式语法参考
相同切入点的抽取

package com.spring.spring5.annotaion;

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

//增强的类
@Aspect//表示生成代理对象
@Component
public class UserProxy {
    //前置通知
    @Before(value = "execution(* com.spring.spring5.annotaion.User.add(..))")//表示作为前置通知
    public void before(){
        System.out.println("Before......");
    }

    //最终通知，不管有没有异常在方法之后都执行
    @After(value = "execution(* com.spring.spring5.annotaion.User.add(..))")
    public void after(){
        System.out.println("After......");
    }

    //后置通知（返回通知），方法无异常结束时执行
    @AfterReturning(value = "execution(* com.spring.spring5.annotaion.User.add(..))")
    public void afterReturning(){
        System.out.println("AfterReturning......");
    }

    //异常通知，add()有异常时才会执行
    @AfterThrowing(value = "execution(* com.spring.spring5.annotaion.User.add(..))")
    public void afterThrowing(){
        System.out.println("AfterThrowing......");
    }

    //环绕通知，在方法之前和之后执行
    @Around("execution(* com.spring.spring5.annotaion.User.add(..))")
    public void around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
        System.out.println("Around之前......");
        proceedingJoinPoint.proceed();
        System.out.println("Around之后......");
    }
}

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6. 测试

package com.spring.spring5.annotaion.test;

import com.spring.spring5.annotaion.User;
import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestAnnotation {
    @Test
    public void test(){
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring-config.xml");
        User user = context.getBean("user", User.class);
        user.add();
        /*
        Around之前......
        Before......
        add.......
        Around之后......
        After......
        AfterReturning......
        */
    }
}
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2.1.1 完全注解开发

配置类：

package com.spring.spring5.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.EnableAspectJAutoProxy;

@Configuration//配置类
@ComponentScan(basePackages = "com.spring.spring5")//开启组件扫描
@EnableAspectJAutoProxy(proxyTargetClass = true)//开启AspectJ生成代理对象
public class Config {
}

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测试：

@Test
    public void test2(){
        ApplicationContext context = new AnnotationConfigApplicationContext(Config.class);
        User user = context.getBean("user", User.class);
        user.add();
        /*
        Person Before......
        UserProxy Before......
        add.......
        */
    }
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2.2 基于配置文件

2. 创建两个类，增强类和被增强类，创建方法

Book类：

package com.spring.spring5.xml;

//被增强类
public class Book {
    public void buy(){
        System.out.println("buy......");
    }
}

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BookProxy类：

package com.spring.spring5.xml;

//增强类
public class BookProxy {
    public void before() {
        System.out.println("before......");
    }
}

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3. 在spring配置文件中创建两个类对象并配置切入点

<?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: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/aop http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!--创建对象-->
    <bean id="bookProxy" class="com.spring.spring5.xml.BookProxy"></bean>
    <bean id="book" class="com.spring.spring5.xml.Book"></bean>

    <!--配置AOP的增强-->
    <aop:config>
        <!--配置切入点-->
        <aop:pointcut id="p" expression="execution(* com.spring.spring5.xml.Book.buy(..))"></aop:pointcut>

        <!--配置切面-->
        <aop:aspect ref="bookProxy">
            <!--增强作用在具体的方法上-->
            <aop:before method="before" pointcut-ref="p"></aop:before>
        </aop:aspect>
    </aop:config>
</beans>
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4. 测试

package com.spring.spring5.xml;

import org.junit.Test;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestXml {
    @Test
    public void test() {
        ClassPathXmlApplicationContext context = new ClassPathXmlApplicationContext("spring-xml.xml");
        Book book = context.getBean("book", Book.class);
        book.buy();
        /*
        before......
        buy......
        */
    }
}

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