Spring+Maven学习实验- Spring AOP面向切面编程

Posted 2020-09-04 不积跬步无以至千里

在 Spring AOP 中，有 3 个常用的概念，Advices 、 Pointcut 、 Advisor ，解释如下：

• Advices ：表示一个 method 执行前或执行后的动作。
• Pointcut ：表示根据 method 的名字或者正则表达式去拦截一个 method 。
• Advisor ： Advice 和 Pointcut 组成的独立的单元，并且能够传给 proxy factory 对象。

我们可以用名字匹配法和正则表达式匹配法去匹配要拦截的 method 。

1 Pointcut - Name match example

通过 pointcut 和 advisor 拦截 printName() 方法。创建一个 NameMatchMethodPointcut 的 bean ，将你想拦截的方法的名字 printName 注入到属性 mappedName ，如下：

<bean id="customerPointcut"
        class="org.springframework.aop.support.NameMatchMethodPointcut">
        <property name="mappedName" value="printName" />
</bean>

创建一个 DefaultPointcutAdvisor 的 advisor bean ，将 pointcut 和 advice 关联起来。

<bean id="customerAdvisor"
        class="org.springframework.aop.support.DefaultPointcutAdvisor">
        <property name="pointcut" ref="customerPointcut" />
        <property name="advice" ref=" hijackAroundMethodBean " />
</bean>

更改代理的 interceptorNames 值，将上边的 advisor（ customerAdvisor ）替代原来的 hijackAroundMethodBean 。

<bean id="customerServiceProxy"
        class="org.springframework.aop.framework.ProxyFactoryBean">

        <property name="target" ref="customerService" />

        <property name="interceptorNames">
            <list>
                <value>customerAdvisor</value>
            </list>
        </property>
</bean>

整个xml如下：

<?xml version="1.0" encoding="UTF-8"?>
<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.CustomerService">
        <property name="name" value="Shiyanlou" />
        <property name="url" value="shiyanlou.com" />
    </bean>

    <bean id="hijackAroundMethodBean" class="com.shiyanlou.spring.aop.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="customerPointcut" class="org.springframework.aop.support.NameMatchMethodPointcut">
        <property name="mappedName" value="printName" />
    </bean>

    <bean id="customerAdvisor" class="org.springframework.aop.support.DefaultPointcutAdvisor">
        <property name="pointcut" ref="customerPointcut" />
        <property name="advice" ref="hijackAroundMethodBean" />
    </bean>

</beans>

2 Pointcut - Regular exxpression match example

你可以配置用正则表达式匹配需要拦截的 method ，如下配置：

<?xml version="1.0" encoding="UTF-8"?>
<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="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.RegexpMethodPointcutAdvisor">
        <property name="patterns">
            <list>
                <value>.*URL.*</value>
            </list>
        </property>
        <property name="advice" ref="hijackAroundMethodBean" />
    </bean>


</beans>