A simple try on IntroductionInterceptor

[Bang Nguyen]

Hi, I've started experimenting Spring just for sometimes. Recently I got a strange case with IntroductionInterceptor. I don't know it's my understanding problem or the way I configured the framework was wrong.

Main Idea: I wanted to implement a greeting service which has the method sayGreeting(). Then I added an Introduction Interceptor to control if people can use that service or not.

public class GreetingServiceImpl implements GreetingService {
.....
    @Override
    public void sayGreeting() {
        System.out.println(greeting);
    }
....
}

public class GreetingMixin extends DelegatingIntroductionInterceptor
        implements LockMixin {

    private boolean locked;

    @Override
    public void lock() {
        this.locked = true;
    }

    @Override
    public void unlock() {
        this.locked = false;
    }

    @Override
    public boolean locked() {
        return this.locked;
    }

    @Override
    public Object invoke(MethodInvocation invocation) throws Throwable {
        if (locked() && invocation.getMethod().getName().indexOf("set") == 0)
            throw new RuntimeException("Locked already");
        return super.invoke(invocation);
    }
}

public class StandaloneHelloApp {

    public static void main(String[] args) throws Exception {
        Resource resource = new FileSystemResource("src/main/java/hello.xml");
        BeanFactory factory =
                new XmlBeanFactory(resource);
        GreetingService greetingService =
                (GreetingService) factory.getBean("greetingService");
        LockMixin lockMixin= (LockMixin) factory.getBean("lockMixin");
        lockMixin.lock();
        greetingService.sayGreeting();


    }
}

so as you can see I called the lock() method on the lockMixin but the method was still running smoothly without throwing any RuntimeException.

This is my configuration of hello.xml:

<beans>
    <bean id="greetingServiceTarget"
          class="com.bang.helloworld.GreetingServiceImpl" singleton="false">
        <property name="greeting">
            <value>Buenos Dias!</value>
        </property>
    </bean>
    <bean id="lockMixin"
          class="com.bang.helloworld.GreetingMixin" [b]singleton="true"[/b]/>
    <bean id="lockAdvisor"
          class="org.springframework.aop.support.DefaultIntroductionAdvisor" 
          [b]singleton="true"[/b]>
        <constructor-arg>
            <ref bean="lockMixin"/>
        </constructor-arg>
    </bean>
    <bean id="greetingService"
          class="org.springframework.aop.framework.ProxyFactoryBean">
        <property name="proxyTargetClass">
            <value>false</value>
        </property>
        
        <property name="proxyInterfaces">
            <list>
                <value>com.bang.helloworld.GreetingService</value>
            </list>
        </property>
        <property name="interceptorNames">
            <list>
                <value>lockAdvisor</value>
            </list>
        </property>
        <property name="target">
            <ref bean="greetingServiceTarget"/>
        </property>
    </bean>
</beans>

Please pay attention to the bold parts with singleton="true"! I want to try that so I can retrieve back the bean for lockMixin and call the method lock() on it!

Please help me out!

[Bang Nguyen]

Really appreciate your time if anyone can help me on this! Thank very much!