Spring基础：AOP编程(5)

基于Schema的AOP编程
基于AspectJ的AOP编程已经可以满足我们的编程需要，为什么这里还要做一套基于Schema的逻辑呢，这里有两个理由：
1.Java语言直到5.0才支持注解功能，所以在5.0之前的版本如果也想体验到AspectJ的便利，就需要使用特殊的方法。
2.AspectJ无法针对切面Advisor编程，但是Schema可以。

前置增强：

public class AdviceMethods {
    public void preGreeting() {
        System.out.println("--how are you--");
    }
}

<bean id="naiveWaiter" class="com.firethewhole.maventest08.NaiveWaiter"/>
<bean id="naughtyWaiter" class="com.firethewhole.maventest08.NaughtyWaiter"/>
<bean id="adviceMethods" class="com.firethewhole.maventest08.schema.AdviceMethods"/>
<bean id="smartSeller" class="com.firethewhole.maventest08.SmartSeller"/>
<aop:config proxy-target-class="true">
    <aop:aspect ref="adviceMethods">
        <aop:pointcut expression="target(com.firethewhole.maventest08.NaiveWaiter) and execution(* greetTo(..))" id="greetToPointcut"/>
        <aop:before method="preGreeting" pointcut-ref="greetToPointcut"/>
    </aop:aspect>
</aop:config>

测试代码：

public class SchemaProxyTest {
    public static void main(String[] args) {
        String configLocation = "com/firethewhole/maventest08/schema/beans.xml";
        ApplicationContext ctx = new ClassPathXmlApplicationContext(configLocation);
        Waiter naiveWaiter = (Waiter) ctx.getBean("naiveWaiter");
        Waiter naughtyWaiter = (Waiter) ctx.getBean("naughtyWaiter");
        naiveWaiter.greetTo("John");
        naughtyWaiter.greetTo("John");
    }
}

输出：

--how are you--
NaiveWaiter.greet to John
NaughtyWaiter: greet to John

我们并没有使用注解或者AspectJ的相关功能，只是在XML配置类相关的Bean和<aop:config>，也达到了相同的效果。

后置增强：

<aop:after-returning method="afterReturning" pointcut="target(com.firethewhole.maventest08.SmartSeller)" returning="retVal"/>

可以看到我们依然可以在配置文件中绑定返回值。

环绕增强：

<aop:around method="aroundMethod" pointcut="execution(* serveTo(..)) and target(com.firethewhole.maventest08.Waiter)"/>

环绕增强可以绑定连接点信息

public void aroundMethod(ProceedingJoinPoint pjp) throws Throwable {
    System.out.println("开始进入方法：" + pjp.getTarget().getClass());
    System.out.println("参数为：" + pjp.getArgs()[0]);
    pjp.proceed();
    System.out.println("开始退出方法：" + pjp.getTarget().getClass());
}

抛出异常增强：

<aop:after-throwing method="afterThrowingMethod" pointcut="execution(* checkBill(..)) and target(com.firethewhole.maventest08.SmartSeller)" throwing="iae"/>

public void afterThrowingMethod(IllegalArgumentException iae) {
    System.out.println("抛出异常：" + iae.getMessage());
}

这里绑定类异常信息。

Final增强：

<aop:after method="afterMethod" pointcut="execution(* com..*.Waiter.greetTo(..))"/>

无论是否有异常都会执行。

引介增强：

<aop:declare-parents types-matching="com.firethewhole.maventest08.Waiter+" implement-interface="com.firethewhole.maventest08.Seller" default-impl="com.firethewhole.maventest08.SmartSeller"/>

增强绑定参数：

<aop:before method="bindParams" pointcut="target(com.firethewhole.maventest08.NaiveWaiter) and args(name,num,..)"/>

public void bindParams(int num, String name) {
    System.out.println("-----bindParams-----");
    System.out.println("name:" + name);
    System.out.println("num:" + num);
    System.out.println("-----bindParams-----");
}

public class SchemaProxyTest {
    public static void main(String[] args) {
        String configLocation = "com/firethewhole/maventest08/schema/beans.xml";
        ApplicationContext ctx = new ClassPathXmlApplicationContext(configLocation);
        Waiter naiveWaiter = (Waiter) ctx.getBean("naiveWaiter");
        ((NaiveWaiter)naiveWaiter).smile("John", 2);
    }
}

输出：

-----bindParams-----
name:John
num:2
-----bindParams-----
NaiveWaiter.smile to John 2 times