Spring AOP之切面

静态普通方法名匹配切面

1.定义两个业务类  服务生和售货员

public class Waiter {

    public void greetTo(String name) {

        System.out.println("waiter greet to " + name + "...");
    }

    public void serveTo(String name) {

        System.out.println("waiter serving " + name + "...");
    }
}

public class Seller {

    public void greetTo(String name) {

        System.out.println("seller greet to " + name + "...");
    }


}

Seller和Waiter拥有一个相同名称的方法greetTo()；

现在通过StaticMathodMatcherPointcutAdvisor定义一个切面，在Waiter类greetTo()方法调用前织入一个前置增强。

public class GreetingAdvisor extends StaticMethodMatcherPointcutAdvisor {


    //切点方法匹配  匹配greetTo()方法
    public boolean matches(Method method, Class<?> aClass) {

        return "greetTo".equals(method.getName());
    }

    //仅匹配Waiter类及其子类
    @Override
    public ClassFilter getClassFilter() {

        return new ClassFilter() {
            public boolean matches(Class<?> clazz) {

                return Waiter.class.isAssignableFrom(clazz);
            }
        };
    }
}

StaticMathodMatcherPointcutAdvisor抽象为唯一定义的方法为matches()方法。

默认情况该切面匹配所有类，这里通过覆盖getClassFilter()方法，让他仅匹配Waiter类及其子类。

定义一个前置增强

public class GreetingBeforeAdvice implements MethodBeforeAdvice {


    public void before(Method method, Object[] args, Object o) throws Throwable {

        System.out.println(o.getClass().getName() + "." + method.getName());

        String clientName = (String) args[0];

        System.out.println("How are you ! Mr " + clientName + " .");
    }
}

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:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <!-- 代理对象 -->
    <bean id="waiterTarget" class="com.smart.advisor.Waiter"/>
    <bean id="sellerTarget" class="com.smart.advisor.Seller"/>

    <!-- 前置增强 -->
    <bean id="greetingBeforeAdvice" class="com.smart.advisor.GreetingBeforeAdvice"/>

    <!-- 配置切面 向切面注入一个前置增强 -->
    <bean id="greetingAdvisor" class="com.smart.advisor.GreetingAdvisor"
          p:advice-ref="greetingBeforeAdvice"/>

    <!-- 配置代理 -->
    <bean id="waiterProxy" class="org.springframework.aop.framework.ProxyFactoryBean"
          p:interceptorNames="greetingAdvisor"
          p:target-ref="waiterTarget"
          p:proxyTargetClass="true"/>

    <!-- 配置代理 -->
    <bean id="sellerProxy" class="org.springframework.aop.framework.ProxyFactoryBean"
          p:interceptorNames="greetingAdvisor"
          p:target-ref="sellerTarget"
          p:proxyTargetClass="true"/>
</beans>

测试：

public class AdvisorTest {

    public static void main(String[] args) {

        String configPath = "beans.xml";
        ApplicationContext applicationContext = new ClassPathXmlApplicationContext(configPath);
        Waiter waiterProxy = (Waiter) applicationContext.getBean("waiterProxy");
        Seller sellerProxy = (Seller) applicationContext.getBean("sellerProxy");
        waiterProxy.greetTo("john");
        System.out.println("---------------");
        waiterProxy.serveTo("john");
        System.out.println("---------------");
        sellerProxy.greetTo("messi");
    }
}

运行结果：

com.smart.advisor.Waiter.greetTo
How are you ! Mr john .
waiter greet to john...
---------------
waiter serving john...
---------------
seller greet to messi...

切面只织入了Waiter类的greetTo()方法之前，Waiter类的serveTo()和Seller类的greetTo()方法都没有织入切面。

静态正则表达式匹配切面

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

    <!-- 代理对象 -->
    <bean id="waiterTarget" class="com.smart.advisor.Waiter"/>
    <bean id="sellerTarget" class="com.smart.advisor.Seller"/>

    <!-- 前置增强 -->
    <bean id="greetingBeforeAdvice" class="com.smart.advisor.GreetingBeforeAdvice"/>

    <!-- 配置切面 向切面注入一个前置增强 -->
    <bean id="greetingAdvisor" class="com.smart.advisor.GreetingAdvisor"
          p:advice-ref="greetingBeforeAdvice"/>

    <!--通过正则表达式定义切面 -->
    <bean id="regexpAdvisor" class="org.springframework.aop.support.RegexpMethodPointcutAdvisor"
          p:advice-ref="greetingBeforeAdvice"
          p:patterns=".*greet.*"
    />

    <!-- 配置代理 -->
    <bean id="waiterProxy" class="org.springframework.aop.framework.ProxyFactoryBean"
          p:interceptorNames="regexpAdvisor"
          p:target-ref="waiterTarget"
          p:proxyTargetClass="true"
    />

    <bean id="waiterProxy1" class="org.springframework.aop.framework.ProxyFactoryBean"
          p:interceptorNames="greetingAdvisor"
          p:target-ref="waiterTarget"
          p:proxyTargetClass="true"/>

    <!-- 配置代理 -->
    <bean id="sellerProxy" class="org.springframework.aop.framework.ProxyFactoryBean"
          p:interceptorNames="greetingAdvisor"
          p:target-ref="sellerTarget"
          p:proxyTargetClass="true"/>
</beans>

结果与第一种方法相同

自动代理机制 让容器自动生成代理，Spring使用BeanPostProcessor自动完成