jquery ajax 不进入后台action

前台是一个onchange的触发事件：
 function refreshCust(){
  var customer = $("#se_cust").val();
  if(customer == 0){
  return;
  }
  var param="customer="+customer;
              $.ajax({
                   type: "POST",
                   url: "columnManager!getProFileInfo.action",
                   data: param,
                   //dataType: "json",
                  contentType: "application/json;charset=utf-8",
                   success: function(json){
                       alert("success!");
                   },
                   error:function(){
                 alert("系统错误");
                 return false;
                   }
               });
  }后台：
public void getProFileInfo() throws IOException{
        HttpServletResponse response = ServletActionContext.getResponse();
        proFileList = customDao.getTransource(customer);
        response.setCharacterEncoding("utf-8");
        response.getWriter().print(JSONObject.fromObject(proFileList));
    }其中proFileList是：
private List<Map<String,Object>> proFileList;
就是不进action,每次执行都返回“success”，请高手指教jqueryajaxjsonactionfunction