public class IsUserLoginAdvice{

  public void isUserLogin() throws UserNotFoundException{
    // TODO Auto-generated method stub
    int id=0;
    Map sessionMap=ActionContext.getContext().getSession();
    System.out.println(sessionMap);
    try {
      //这里在一开始时userId是不存在的可能会抛出NullPointException，catch起来
      id=(int) sessionMap.get("userId");
      //在用户注销时我把session中的userId设为0
      if(id==0){
        throw new UserNotFoundException();
      }
    } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
      throw new UserNotFoundException();
    }
  }
}

  <package name="struts-global" namespace="/" extends="struts-default">

    <global-results>
      <result name="userNotFound">/web_resource/error_jsp/user_not_found.jsp
      </result>
    </global-results>

    <global-exception-mappings>
      <exception-mapping result="userNotFound" exception="com.lsj.market.exception.UserNotFoundException"></exception-mapping>
    </global-exception-mappings>
  </package>

<package name="com.lsj.market.action.user" extends="struts-global">

  <!-- aop设置 --> 
  <aop:config proxy-target-class="true">
    <aop:aspect ref="isUserLoginAdvice">
      <aop:pointcut id="isUserLoginPointcut" 
        expression="execution (* com.lsj.market.action..GetUser*.*(..)) 
          or execution (* com.lsj.market.action..*Update*Action*.*(..)) 
          or execution (* com.lsj.market.action..*Delete*Action*.*(..))
          or execution (* com.lsj.market.action..GetMarketCar*.*(..))
          or execution (* com.lsj.market.action..MarketCar*.*(..))
          or execution (* com.lsj.market.action..ToFlower*.*(..))
          or execution (* com.lsj.market.action..Flower*Add*.*(..))"/>
      <aop:before method="isUserLogin" pointcut-ref="isUserLoginPointcut"/>
    </aop:aspect>
  </aop:config>
  <!-- 声明advice Bean -->
  <bean id="isUserLoginAdvice" class="com.lsj.market.aop.IsUserLoginAdvice"></bean>

<constant name="struts.objectFactory" value="spring" />

  <!-- 总是确保使用spring的自动装备策略 -->
  <constant name="struts.objectFactory.spring.autoWire.alwaysRespect" value="true" />