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; 
}