spring AOP小例子

下面編碼開始：

讓我們先寫兩個簡單的類：

package com.longthsoft.learn.spring.models;

public class A {
    public void sayHello() {
        System.out.println("Hello, I'm a");
    }
}

package com.longthsoft.learn.spring.models;

public class B {
    public void sayHi() {
        System.out.println("Hi, I'm b");
    }
}

沒什麼實際的東西， 只是小A和小B在打招呼

接下來把他們交給Spring吧（有點殘忍）。

<?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-2.0.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">

    <bean id="a" class="com.longthsoft.learn.spring.models.A" />
    <bean id="b" class="com.longthsoft.learn.spring.models.B" />
</beans>

接下來寫個Boot

package com.longthsoft.learn.spring;

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

import com.longthsoft.learn.spring.models.A;
import com.longthsoft.learn.spring.models.B;

public final class Boot {

    public static void main(String[] args) {
        ApplicationContext ctx = new ClassPathXmlApplicationContext("applicationContext.xml");
        A a = (A) ctx.getBean("a");
        a.sayHello();

        B b = (B) ctx.getBean("b");
        b.sayHi();
    }

}

嘿， 這裏的運行結果不帖了， 大家腦子裏閃過即可。

聖誕到了， 小A小B 介紹完自己之後，也應該說句 "Merry Christmas"

Spring 說， 既然你們交給我， 這等 routine 就不用再麻煩了， 直接一併處理掉。

於是：

package com.longthsoft.learn.spring;

import org.aspectj.lang.annotation.AfterReturning;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;

@Aspect
public class SimpleAspect {

    @Pointcut("execution(* com.longthsoft.learn.spring.models.*.say*())")
    public void simplePointcut() { }

    @AfterReturning(pointcut="simplePointcut()")
    public void simpleAdvice() {
        System.out.println("Merry Christmas");
    }
}

然後修改一下配置文件

<?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:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.0.xsd">

    <aop:aspectj-autoproxy />

    <bean id="a" class="com.longthsoft.learn.spring.models.A" />
    <bean id="b" class="com.longthsoft.learn.spring.models.B" />

    <bean id="simpleAspect" class="com.longthsoft.learn.spring.SimpleAspect" />
</beans>

OK， 運行一下：

Hello, I'm a

Merry Christmas

Hi, I'm b

Merry Christmas