如何使用struts 2在extjs网格中显示数据

Question

我是struts 2和extjs的新手。我想显示来自struts到extjs网格的数据 那么，我们怎么能显示出来呢？ 我的struts.xml是

<package name="example" extends="json-default" > 
    <action name="gridDisplay" class="sample.extjs.StudentList" method="GridData"> 
        <result type="json" /> 
    </action> 
</package>

java代码

 public String GridData() throws Exception{

// this list returns all the name of student in arraylist
    List listdata = studentInfo.listNameDetails();

    if(!listdata.isEmpty()){

        JSONObject myobje = new JSONObject(); // json object
        myobje.put("title", listdata); // create a json of the student list

      //ServletActionContext.getResponse().getOutputStream().println(myobje+"");
    // also tried this but didnt work

        return myobje.toString(); 
    }else{
        ServletActionContext.getResponse().getOutputStream().print("0");
         return null;
    }
}

extjs代码是

Ext.onReady( function() {
Ext.define("StudentList",{
    extend:"Ext.data.Model",
    fields:["firstName","lastName","Gender"]
});
  var ListStore = Ext.create("Ext.data.JsonStore",{
   model: "StudentList",
   proxy: {
       type:'ajax',
       url:"/gridDisplay",
       reader:{
           type:"json",
           root:"title"
       }
    }    
  });
   ListStore.load();
  Ext.create("Ext.grid.Panel",{
    title:"List Of Student",
    store: ListStore,
    renderTo: Ext.getBody(),
    height:250,
    width:500,
    columns:[        
        {text: 'firstName',  dataIndex: 'firstName',  flex: 2},
        {text: 'lastName',  dataIndex: 'lastName',  flex: 2},
        {text: 'Gender',  dataIndex: 'Gender',  flex: 2},        
     ]
  });
});

这是我的extjs代码，我想在网格中显示数据。   我在json formate中对struts的调用是否正确？

感谢您的回复