using System;
using System.Web;

namespace TestGridSimple
{
     public class Handler : IHttpHandler
     {
         public void ProcessRequest(HttpContext context)
         {
             string response="blah-blah-blah";

             context.Response.Clear();
             context.Response.ClearHeaders();
             context.Response.ClearContent();
             context.Response.CacheControl = "no-cache";
             context.Response.Expires = -1;
             context.Response.ContentType = "application/json; charset=utf-8";
             context.Response.Charset = "utf=8";
             context.Response.ContentEncoding = Encoding.UTF8;
             byte[] bytes = context.Response.ContentEncoding.GetBytes(response);
             context.Response.AddHeader("Content-Length", bytes.Length.ToString());
             context.Response.Write(response);
             context.Response.Flush();
             context.Response.Close();
             context.Response.End();
         }

         public bool IsReusable
         {
             get { return false; }
         }
     }
}

 context.Response.ContentType = "application/json; charset=utf-8";
             context.Response.Charset = "utf=8";
             context.Response.ContentEncoding = Encoding.UTF8;