Spring框架自动创建 proxy

利用 BeanNameAutoProxyCreator 自动创建 proxy

在前面两节的例子中，在配置文件中，我们必须手动为每一个需要 AOP 的 bean 创建 Proxy bean（ProxyFactoryBean）。

这不是一个好的体验，例如，我们想让 DAO 层的所有 bean 都支持 AOP，以便写 SQL 日志，那么必须手工创建很多的 ProxyFactoryBean，这样会直接导致 xml 配置文件内容成几何级的倍增，不利于 xml 配置维护。幸运的是，Spring 有两种方法，可以为你自动创建 proxy。

手工创建 ProxyFactoryBean 如下：

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

    <bean id = "customerService" class = " com.shiyanlou.spring.aop.advice.CustomerService">
        <property name = "name" value = "lanqiao" />
        <property name = "url" value = "lanqiao.cn" />
    </bean>

    <bean id = "hijackAroundMethodBean" class = " com.shiyanlou.spring.aop.advice.HijackAroundMethod" />

    <bean id = "customerServiceProxy"
        class = "org.springframework.aop.framework.ProxyFactoryBean">
        <property name = "target" ref = "customerService" />
        <property name = "interceptorNames">
            <list>
                <value>customerAdvisor</value>
            </list>
        </property>
    </bean>

    <bean id = "customerAdvisor"    class = "org.springframework.aop.support.NameMatchMethodPointcutAdvisor">
        <property name = "mappedName" value = "printName" />
        <property name = "advice" ref = " hijackAroundMethodBean " />
    </bean>
</beans>

配置完后要得到 customerServiceProxy，需要如下代码：

CustomerService cust = (CustomerService) appContext.getBean("customerServiceProxy");

在自动模式中，我们需要创建 BeanNameAutoProxyCreator，将所有的 bean（通过名字或正则表达式匹配）和 advisor 形成一个独立的单元，SpringAOPAdvice.xml 配置如下：

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

    <bean id = "customerService" class = " com.shiyanlou.spring.aop.advice.CustomerService">
        <property name = "name" value = "lanqiao" />
        <property name = "url" value = "lanqiao.cn" />
    </bean>

    <bean id = "hijackAroundMethodBean" class = " com.shiyanlou.spring.aop.advice.HijackAroundMethod" />

    <bean
    class = "org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator">
        <property name = "beanNames">
            <list>
                <value>*Service</value>
            </list>
        </property>
        <property name = "interceptorNames">
            <list>
                <value>customerAdvisor</value>
            </list>
        </property>
    </bean>

    <bean id = "customerAdvisor" class = "org.springframework.aop.support.NameMatchMethodPointcutAdvisor">
        <property name = "mappedName" value = "printName" />
        <property name = "advice" ref = "hijackAroundMethodBean" />
    </bean>
</beans>

以上配置中只要 bean 的 id 符合 *Service，就会自动创建 proxy，所以，可以用以下代码获得 proxy。

CustomerService cust = (CustomerService) appContext.getBean("customerService");

利用 DefaultAdvisorAutoProxyCreator 创建 Proxy

这种方式利用 DefaultAdvisorAutoProxyCreator 实现自动创建 Proxy，此种方式威力巨大，任何匹配 Advisor 的 bean，都会自动创建 Proxy 实现 AOP，所以慎用。

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

    <bean id = "customerService" class = " com.shiyanlou.spring.aop.advice.CustomerService">
        <property name = "name" value = "Shiyanlou" />
        <property name  ="url" value = "shiyanlou.com" />
    </bean>

    <bean id = "hijackAroundMethodBean" class = " com.shiyanlou.spring.aop.advice.HijackAroundMethod" />

    <bean id = "customerAdvisor"
        class = "org.springframework.aop.support.NameMatchMethodPointcutAdvisor">
        <property name = "mappedName" value = "printName" />
        <property name = "advice" ref = "hijackAroundMethodBean" />
    </bean>

    <bean
        class = "org.springframework.aop.framework.autoproxy.DefaultAdvisorAutoProxyCreator" />
</beans>

以上例子中，xml 中任何 bean，只要有 method 名字为 printName，使用以下代码时，都会自动创建 Proxy，来支持 AOP。

CustomerService cust = (CustomerService) appContext.getBean("customerService");