Ajax校验是否重复的实现代码

@ResponseBody @RequestMapping("entityFindByCode") public String entityFindByCode(Entity bean, HttpSession httpSession, Model m,HttpServletResponse res) throws IOException{   res.setContentType("text/plain; charset=UTF-8");   //res.reset();   //PrintWriter out = res.getWriter();   String data=null;   @SuppressWarnings("unchecked")   List<Entity> list = (List<Entity>) this.service.find("beanByCode", "Entity", new Object[]{bean.getCode()});   if(list.size()==0){     data="YES";   }else{     data="NO";   }   res.getOutputStream().write(data.getBytes());   //out.print(data);   //out.flush();   //out.close();   return data; }

$.ajax({       url    :'entityFindByCode',       type   :'post',       dataType :'text',       data   :{code:$("#code").val()},//{key,value}       success  :function(data) {         if (data == "YES"){           document.getElementById("msg-code").innerHTML = "(<fmt:message key='warn.field.required.unique' bundle='${bundle }' />)";           return true;         }         else {           $("#div-code").addClass("has-error");           document.getElementsByName("code")[0].value = "";            //document.getElementsByName("code")[0].setAttribute("placeholder", "<fmt:message key='warn.duplicate' bundle='${bundle }' />");            document.getElementById("msg-code").innerHTML = "(<fmt:message key='warn.duplicate' bundle='${bundle }' /> !!!)";           return false;         }       }     });