HttpHandler动态生成图片

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Web;
namespace Web1
{
    /// <summary>
    /// ContentTypeTest 的摘要说明
    /// </summary>
    public class ContentTypeTest : IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            context.Response.ContentType = "image/gif";
            string FilePath = context.Server.MapPath("~/1.gif");
            using(Stream instream=File.OpenRead(FilePath))//new FileStream(....);
            {
                instream.CopyTo(context.Response.OutputStream);
            }
       
        }
        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }
}