ajax前台传到后台乱码，显示问号的问题

         response.setContentType("text/html;charset=gbk");
         response.setHeader("Cache-Control", "no-cache");
         response.setCharacterEncoding("gbk");
4         PrintWriter out=response.getWriter();
         request.setCharacterEncoding("gbk");
         //获取搜索框输入的内容
 
         String userqygs=request.getParameter("userQygs");
         userqygs=new String(userqygs.getBytes("iso-8859-1"), "gbk");

我的前后台编码都为  gbk,可以按照自己的编码改