$("#nickForm").ajaxSubmit({
     type: "post",
     url: "http://localhost:8080/test/myspace.do?method=updateNick¶m=1",
     dataType: "json",
     success: function(result){

           //返回提示信息      
           alert(result.nickMsg);
     }
 });

public ActionForward toUpdateNickName(ActionMapping mapping, ActionForm form,
   HttpServletRequest request, HttpServletResponse response){

       PrintWriter pw = response.getWriter();
      JSONObject obj = new JSONObject();

      obj.put("nickMsg", "昵称修改成功！");

      pw.print(obj);
      pw.close();

}