异常：Name for argument type [java.lang.String] not available, and parameter name information not found in class file either

解决：方案一：在项目名上右键选择Properties—》JavaCompiler—》Add variable attributs...打上对号

         方案二：主动声明参数绑定，

                       public void json(HttpServletResponse response,Model model , @RequestParam(value="username") String username)