Spring AOP切面变成——创建增强类

说明

Spring使用增强类定义横向逻辑，同时Spring只支持方法连接点，增量类还包含在方法的哪一点添加横切代码的方位信息。所以增强既包含横向逻辑，又包含部分连接点的信息。

类型

按着增强在目标类方法的连接点位置，分为

1. 前置增强
2. 后置增强
3. 环绕增强
4. 异常抛出增强
5. 引介增强

前置增强

场景：服务生提供2中服务：欢迎顾客、服务顾客

package com.jihite;

public interface Waiter {
    void greetTo(String name);
    void serveTo(String name);
}

新来的服务生情况如下

package com.jihite;

public class NaiveWaiter implements Waiter{
    @Override
    public void greetTo(String name) {
        System.out.println("Greet to " + name);
    }

    @Override
    public void serveTo(String name) {
        System.out.println("Serve to " + name);
    }
}

新来的服务生上来就提供服务，比较生猛，在做每件事之前都改打个招呼，下面定义前置增强类

package com.jihite;
import org.springframework.aop.MethodBeforeAdvice;

import java.lang.reflect.Method;

public class GreetingBeforeAdvice implements MethodBeforeAdvice{
    @Override
    public void before(Method method, Object[] args, Object obj) throws Throwable {
        String clientName = (String)args[0];
        System.out.println("How are you! Mr." + clientName);
    }
}

在Spring中配置

在src/main/resources中定义beans.xml

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean id="greetingBeforeAdvice" class="com.jihite.GreetingBeforeAdvice"/>
    <bean id="targetBefore" class="com.jihite.NaiveWaiter"/>
    <bean id="waiterBefore" class="org.springframework.aop.framework.ProxyFactoryBean"
          p:interceptorNames="greetingBeforeAdvice"
          p:target-ref="targetBefore"
          p:proxyTargetClass="true"
          />
</beans>

测试

public class BeforeAdviceTest {
    private Waiter target;
    private BeforeAdvice advice;
    private ProxyFactory pf;

    @BeforeTest
    public void init() {
        target = new NaiveWaiter();
        advice = new GreetingBeforeAdvice();
        pf = new ProxyFactory();
        pf.setTarget(target);
        pf.addAdvice(advice);
    }
}

结果

How are you! Mr.Jphn
Greet to Jphn
How are you! Mr.Tom
Serve to Tom

其他类型的增强类与前置增强类似，可参考代码

代码

链接