用ajax如何从action那里拿数据？

public String ajaxSubmit(){
  try{
   Integer tId = this.TId;
   String tName = this.TName;
   System.out.println(tId+":"+tName);
   PrintWriter p = null;
   HttpServletResponse response = ServletActionContext.getResponse();
   response.setContentType("text;charset=utf-8");
   SpsTitle spsTitle = createTitleService.findByTid(tId);
   spsTitle.setTName(tName);
   createTitleService.update(spsTitle);
   p = response.getWriter();
   JSONObject jsonObject = JSONObject.fromObject(spsTitle);
   p.print(jsonObject);
//   p.print(spsTitle.getTName());
   p.flush();
   p.close();
  }catch(Exception e){
   e.printStackTrace();
  }
  return null;
 }

 

 

 $.ajax({type:'POST',
      url:'createTitleAction!ajaxSubmit',
      data:{TId:id ,TName:tName},   // 数据 
      success:function(data){
    alert(data);//为什么我拿不到数据？ 要怎么拿？
       },
     error:function(err){
      alert("失败");
    }})