aop 笔记 引入

引入和其它类型的spring通知有所不同.其它类型的通知是在方法调用的周围织入到不同的连接点.而引入则是影响整个类.
引入让你能动态地建立复合对象.
spring 通过一个特殊的方法拦截接口IntroductionInterceptor
                     

java 代码

boolean implementsInterface(Class intf);
这个方法判断是否是引入的接口

要引入的接口

java 代码

package aop.introduction;

public interface IChange {
        public boolean ichange();
}

现在我们实现一个introductionInterceptor

java 代码

package aop.introduction;

import org.aopalliance.intercept.MethodInvocation;
import org.springframework.aop.IntroductionInterceptor;


public class IChangeAdvisora implements IntroductionInterceptor,IChange{

    public Object invoke(MethodInvocation m) throws Throwable {
        if(implementsInterface(m.getMethod().getDeclaringClass())){
            return m.getMethod().invoke(this, m.getArguments());
            //通过MethodInvocation 和invoke代理要引入的方法
        }else{
            return m.proceed();  //委托其它方法,不是引入,就像那个环绕通知
        }
    }

    public boolean implementsInterface(Class intf) {
        return intf.isAssignableFrom(IChange.class);
    }

    public boolean ichange() {
        System.out.println("intrduction");
        return false;
    }

}

spring 为我们提供一个方便类的处理大多数的应用.DelegatingIntroductInterceptor

java 代码

package aop.introduction;

import org.springframework.aop.support.DelegatingIntroductionInterceptor;

public class IChangeAdvisor extends DelegatingIntroductionInterceptor
                   implements IChange  {

    public boolean ichange() {
        // TODO 自动生成方法存根
        System.out.println("ichage");

        return false;
    }
}  //比起上面那个类算得比较简洁,DelegatingIntroductionInterceptor 替我们实现invoke()

如果你想实现方法的拦截调用invoke方法

java 代码

package aop.introduction;

import org.aopalliance.intercept.MethodInvocation;
import org.springframework.aop.support.DelegatingIntroductionInterceptor;

public class IChangeAdvisorb extends DelegatingIntroductionInterceptor implements IChange {

    public boolean ichange() {
        // TODO 自动生成方法存根
        return false;
    }
    public Object invoke(MethodInvocation e) throws Throwable{
        String name = e.getMethod().getName();
        if(name.indexOf("set") == 0){   //这里拦截set方法
            throw new IllegalMonitorStateException();
        }
        return super.invoke(e);
    }

}

下面是配制

java 代码

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
    <bean id="targetbean" class="aop.introduction.TagetBean" />

    <bean id="iChangeAdvisor" class="aop.introduction.IChangeAdvisorb" />
 //这里配制引入advisor,看你用得是那个
    <bean id="advisor"
        class="org.springframework.aop.support.DefaultIntroductionAdvisor">
        <constructor-arg>
            <ref bean="iChangeAdvisor" />
        </constructor-arg>
    </bean>
    <bean id="bean"
        class="org.springframework.aop.framework.ProxyFactoryBean">
        <property name="target">
            <ref bean="targetbean" />
        </property>
        <property name="interceptorNames">
            <list>
                <value>advisor</value>
            </list>
        </property>
        <property name="proxyInterfaces">
            <value>aop.introduction.IChange</value>
        </property>
        <property name="proxyTargetClass">
            <value>true</value>
        </property>
    </bean>
</beans>

java 代码

package aop.introduction;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.FileSystemXmlApplicationContext;

public class IntroductionTest {

    public static void main(String[] args) {
        ApplicationContext ctx = new FileSystemXmlApplicationContext(
                "./src/applicationContext.xml");

        TagetBean bean = (TagetBean) ctx.getBean("bean");
//                 ((IChange) ctx.getBean("bean")).ichange();
       IChange mod = (IChange) bean;

        // test interfaces
        System.out.println("Is TargetBean?: " + (bean instanceof TagetBean));
        System.out.println("Is IsModified?: " + (bean instanceof IChange));

        // test is modified implementation
//        mod.ichange();
       // bean.setName("ddd");
        System.out.println("Has been modified?: " + mod.ichange());
    }
}

评论

2 楼 songfuqiang 2008-07-04  

谢谢楼主,把代码复制下来就可以用了!

1 楼 lindongxiao 2007-07-16  

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
<bean id="targetbean" class="aop.introduction.TagetBean" />

<bean id="iChangeAdvisor" class="aop.introduction.IChangeAdvisorb" />
<bean id="advisor"
class="org.springframework.aop.support.DefaultIntroductionAdvisor">
<constructor-arg>
<ref bean="iChangeAdvisor" />
</constructor-arg>
</bean>
<bean id="bean"
class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="target">
<ref bean="targetbean" />
</property>
<property name="interceptorNames">
<list>
<value>advisor</value>
</list>
</property>
<property name="proxyInterfaces">
<value>aop.introduction.IChange</value>
</property>
<property name="proxyTargetClass">
<value>true</value>
</property>
</bean>
</beans>