java - Struts 2 中的范围模型驱动拦截器未将模型绑定(bind)到 session 范围

Question

我想在多个请求之间共享模型(表单数据)，因此在操作类中实现了 ScopedModelDriven Interceptor。

下面是我的代码

模型 - EventSearchBean.java

public class EventSearchBean {

   private Integer eventId;

   private String location;

   //getters and setters

}

操作 - EventSearchAction

public class EventSearchAction implements ScopedModelDriven<EventSearchBean>
{
   private EventSearchBean eventSearchBean;

   public static final String EVENT_MODEL_SESSION_KEY = "eventSearchBean"; 

   public EventSearchBean getModel() {
        return eventSearchBean;
   }

   public String getScopeKey() {
        return EVENT_MODEL_SESSION_KEY;
   }

   public void setModel(EventSearchBean eventSearchBean) {
        this.eventSearchBean = eventSearchBean;  
   }

   public void setScopeKey(String arg0) {
        // TODO Auto-generated method stub
   }

   public String execute();
   {
     String locale = eventSearchBean.getLocation();

     //Calling business service to fetch events based on location
     List<> eventList = eventManager.getEvents(locale);

     return "success";

   }
}

struts.xml

     <!-- old stack used for other action classes -->

    <interceptor-stack name="oldStack">
      <interceptor-ref name="servletConfig"/>
      <interceptor-ref name="modelDriven"/>
      <interceptor-ref name="exception"/>  
      <interceptor-ref name="fileUpload"/>
      <interceptor-ref name="params"/>
    </interceptor-stack>

   <!-- new stack used for EventSearchAction class -->
    <interceptor-stack name="newStack">
      <interceptor-ref name="servletConfig"/>
      <interceptor-ref name="scopedModelDriven"/>
      <interceptor-ref name="exception"/>  
      <interceptor-ref name="fileUpload"/>
      <interceptor-ref name="params"/>
    </interceptor-stack> 

    <action name="eventSearch" class="com.karthik.EventSearchAction">
       <interceptor-ref name="newStack">
         <param  name="scope">session</param>
         <param  name="name">eventSearchBean</param>
         <param  name="className">com.karthik.beans.EventSearchBean</param> 
       </interceptor-ref>
       <result name="success">/jsp/eventlist.jsp</result>
       <result name="error">/jsp/generalExceptionPage.jsp</result>
    </action>

1) 每个请求都会创建新模型(不会从 session 中复制模型数据以用于后续请求)。 需要更改代码中的哪些内容才能将模型置于 session 范围内？
如何使模型表现得像Struts1中 session 范围的ActionForm？

2) 如果我在声明模型时删除操作类中的 new 运算符，即
private EventSearchBean eventSearchBean;
当我访问操作类中的模型时，出现空指针异常。
如何声明/初始化模型？

3) 仅当在 UI 中提交表单时如何覆盖/更新 session 中的模型？

Answer 1

爆炸defaultStack ，这就是您所定义的:

<interceptor-stack name="defaultStack">
    <interceptor-ref name="exception"/>
    <interceptor-ref name="alias"/>
    <interceptor-ref name="servletConfig"/>
    <interceptor-ref name="i18n"/>
    <interceptor-ref name="prepare"/>
    <interceptor-ref name="chain"/>
    <interceptor-ref name="scopedModelDriven"/> <!-- here -->
    <interceptor-ref name="modelDriven"/>
    <interceptor-ref name="fileUpload"/>
    <interceptor-ref name="checkbox"/>
    <interceptor-ref name="datetime"/>
    <interceptor-ref name="multiselect"/>
    <interceptor-ref name="staticParams"/>
    <interceptor-ref name="actionMappingParams"/>
    <interceptor-ref name="params"/>
    <interceptor-ref name="conversionError"/>
    <interceptor-ref name="validation">
        <param name="excludeMethods">input,back,cancel,browse</param>
    </interceptor-ref>
    <interceptor-ref name="workflow">
        <param name="excludeMethods">input,back,cancel,browse</param>
    </interceptor-ref>
    <interceptor-ref name="debugging"/>
    <interceptor-ref name="deprecation"/>
</interceptor-stack>

<interceptor-ref name="scopedModelDriven">
    <param  name="scope">session</param>
    <param  name="name">eventSearchBean</param>
    <param  name="className">com.karthik.beans.EventSearchBean</param> 
</interceptor-ref>

如您所见，它已经包含 ScopedModelDriven 拦截器。因此，您定义了两次，第一次在 defaultStack 中，第二次手动定义，但只有第二次设置了参数，第一次所有内容都是空的:)

然后，代替

<interceptor-ref name="defaultStack"/>
<interceptor-ref name="scopedModelDriven">
    <param  name="scope">session</param>
    <param  name="name">eventSearchBean</param>
    <param  name="className">com.karthik.beans.EventSearchBean</param> 
</interceptor-ref>

只需使用

<interceptor-ref name="defaultStack">
    <param  name="scopedModelDriven.scope">session</param>
    <param  name="scopedModelDriven.name">eventSearchBean</param>
    <param  name="scopedModelDriven.className">com.karthik.beans.EventSearchBean</param> 
</interceptor-ref>