Extjs4如何处理后台json数据中日期和时间

 [ScriptMethod(ResponseFormat = ResponseFormat.Json), WebMethod(EnableSession = true)]
    public List<EUser> Users()//参数测试用
    {
      List<EUser> l = new List<EUser>();
      Random aran = new Random();
      for (int i = 0; i < 24; i++)
      {
        DateTime date = DateTime.Parse("2015-08-21");
        date = date.AddHours(i);
        var u = new EUser(date,Math.Round(aran.NextDouble() * 100) , 
          Math.Round(aran.NextDouble() * 100), Math.Round(aran.NextDouble() * 100));
        l.Add(u);
      }
      return l;
    }

{ 
   text:'审核时间', 
   dataIndex:'Date', 
   width:200, 
   renderer: function(value) { 
     if(value){ 
       var dt=eval("new " + value.substr(1, value.length - 2)).toString(); 
     return Ext.util.Format.date(dt, "Y年m月d日H时i分s秒");//"Y年m月d日H时i分s秒"    
     }   
    } 
 }

  Hashtable ht = new Hashtable(); 
  ht.Add("total", listu.Count); 
  ht.Add("rows", listu); 
  JsonStr = JsonConvert.SerializeObject(ht);//使用json.net序列化 
  context.Response.Write(JsonStr); 

{ 
  text:'审核时间', 
  dataIndex:'Date', 
  width:200, 
  xtype:'datecolumn', 
  format:'Y年m月d日H时i分s秒' 
}

JSONObject object = JSONObject.fromObject(updateUser); 


//在<span style="font-family: Arial;">JSONObject.toBean加上这行代码就可以了</span> 


JSONUtils.getMorpherRegistry().registerMorpher(new DateMorpher(new String[] {"yyyy-MM-dd", "yyyy-MM-dd HH:mm:ss"})); 


User user = (User) JSONObject.toBean(object, User.class);