spring aop的两种写法aspect和advisor

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剑握在手 2022-02-28 13:51:00 博主文章分类：Spring

首先看个例子，如下

接口代码：

package com.lei.demo.aop.schema;

public interface IHello {
    public void sayHello();
}

接口实现：

package com.lei.demo.aop.schema;

public class HelloService implements IHello {

    public void sayHello() {
        System.out.println("-----Hello World!-----");
    }

}

接下来我们要实现AOP，即调用sayHello方法时切入通知。

1. 第一种方法aop:config中配置aop:pointcut和aop:aspect

定义一个切面支持类HelloAspect.java

package com.lei.demo.aop.schema;

/*
 * 切面支持类
 */
public class HelloAspect {

    //前置通知  
    public void beforeAdvice() {  
        System.out.println("===========before advice");  
    }

    //后置最终通知  
    public void afterFinallyAdvice() {  
        System.out.println("===========after finally advice");
    }
}

Xml配置：Spring-AOP-Schema.xml

<?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-3.2.xsd  
           http://www.springframework.org/schema/aop  
           http://www.springframework.org/schema/aop/spring-aop-3.2.xsd">


    <!-- 目标类 -->
    <bean id="helloService" class="com.lei.demo.aop.schema.HelloService" />

    <bean id="helloAspect" class="com.lei.demo.aop.schema.HelloAspect" />


    <!-- 配置切面 -->
    <!-- aop:advisor，是有顺序的，必须放在aop:pointcut之后 -->
    <aop:config>
        <aop:pointcut id="helloPointcut" expression="execution(* com.lei.demo.aop.schema..*.*(..))" />

        <aop:aspect ref="helloAspect">
            <!—以下使用了两种方法定义切入点  pointcut-ref和pointcut-->
            <aop:before pointcut-ref="helloPointcut" method="beforeAdvice" />
            <aop:after pointcut="execution(* com.lei.demo.aop.schema..*.*(..))" method="afterFinallyAdvice" />
        </aop:aspect>


    </aop:config>
</beans>

以上配置中method="beforeAdvice"、method="afterFinallyAdvice"对应helloAspect中的方法

测试，App.java

package com.lei.demo.aop.schema;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class App {

    private static ApplicationContext ctx;

    public static void main(String[] args) {

        ctx = new ClassPathXmlApplicationContext("Spring-AOP-Schema.xml");

        IHello helloService = ctx.getBean("helloService",IHello.class);

        helloService.sayHello();
    }

}

运行App.java，结果如下：

===========before advice

-----Hello World!-----

===========after finally advice

2. 第二种方法aop:config中配置aop:pointcut和aop:advisor

实现org.aopalliance.intercept.MethodInvocation接口，

HelloAroundAdvice.java如下：

package com.lei.demo.aop.schema;

import java.lang.reflect.Method;

import org.aopalliance.intercept.MethodInterceptor;
import org.aopalliance.intercept.MethodInvocation;

public class HelloAroundAdvice implements MethodInterceptor {

    public Object invoke(MethodInvocation arg0) throws Throwable {

        System.out.println("++++++before advice");
        arg0.proceed();
        System.out.println("++++++after advice");

        return null;
    }

}

Xml配置：Spring-AOP-Schema.xml

<?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-3.2.xsd  
           http://www.springframework.org/schema/aop  
           http://www.springframework.org/schema/aop/spring-aop-3.2.xsd">

    <!-- 目标类 -->
    <bean id="helloService" class="com.lei.demo.aop.schema.HelloService" />

    <bean id="helloArroundAdvice" class="com.lei.demo.aop.schema.HelloAroundAdvice" />

    <!-- 配置切面 -->
    <aop:config>
        <aop:pointcut id="helloPointcut" expression="execution(* com.lei.demo.aop.schema..*.*(..))" />
        <aop:advisor advice-ref="helloArroundAdvice" pointcut-ref="helloPointcut"/>

    </aop:config>
</beans>