C#生成Bar Code Image

public class Barcode : IHttpHandler
    {
        private object _code = "";
        private int _height = 52;
        private string code = "";
        public void ProcessRequest(HttpContext context)
        {
            if (context.Request.QueryString["code"] != null)
            {
                _code = context.Request.QueryString["code"].ToString();
                _code = "*" + _code + "*";
            }
            code = bar_code(_code);
            int p_w = code.Length;
   //int p_h = _height + 20;
   int p_h = _height;
            context.Response.ContentType = "image/gif";
            Bitmap myBitmap = new Bitmap(p_w, p_h);
            Graphics myGrap = Graphics.FromImage(myBitmap);
            myGrap.Clear(Color.White);
            for (int i = 0; i < p_w; i++)
            {
                Pen myPen = new Pen(Color.White, 1);
                if (code.Substring(i, 1) == "|")
                {
                    myPen.Color = Color.Black;
                }
                myGrap.DrawLine(myPen, i, 0, i, _height);
            }
   //myGrap.DrawString(_code.ToString(), new Font("Courier New", 10), new SolidBrush(Color.Black), -4, _height);
            myBitmap.Save(context.Response.OutputStream, ImageFormat.Gif);
            context.Response.End();
        }
        public string bar_code(object str)
        {
            string strTmp = str.ToString();
            string code = strTmp;
            strTmp = strTmp.ToLower();
            strTmp = strTmp.Replace("0", "_|_|__||_||_|");
            strTmp = strTmp.Replace("1", "_||_|__|_|_||");
            strTmp = strTmp.Replace("2", "_|_||__|_|_||");
            strTmp = strTmp.Replace("3", "_||_||__|_|_|");
            strTmp = strTmp.Replace("4", "_|_|__||_|_||");
            strTmp = strTmp.Replace("5", "_||_|__||_|_|");
            strTmp = strTmp.Replace("7", "_|_|__|_||_||");
            strTmp = strTmp.Replace("6", "_|_||__||_|_|");
            strTmp = strTmp.Replace("8", "_||_|__|_||_|");
            strTmp = strTmp.Replace("9", "_|_||__|_||_|");
            strTmp = strTmp.Replace("a", "_||_|_|__|_||");
            strTmp = strTmp.Replace("b", "_|_||_|__|_||");
            strTmp = strTmp.Replace("c", "_||_||_|__|_|");
            strTmp = strTmp.Replace("d", "_|_|_||__|_||");
            strTmp = strTmp.Replace("e", "_||_|_||__|_|");
            strTmp = strTmp.Replace("f", "_|_||_||__|_|");
            strTmp = strTmp.Replace("g", "_|_|_|__||_||");
            strTmp = strTmp.Replace("h", "_||_|_|__||_|");
            strTmp = strTmp.Replace("i", "_|_||_|__||_|");
            strTmp = strTmp.Replace("j", "_|_|_||__||_|");
            strTmp = strTmp.Replace("k", "_||_|_|_|__||");
            strTmp = strTmp.Replace("l", "_|_||_|_|__||");
            strTmp = strTmp.Replace("m", "_||_||_|_|__|");
            strTmp = strTmp.Replace("n", "_|_|_||_|__||");
            strTmp = strTmp.Replace("o", "_||_|_||_|__|");
            strTmp = strTmp.Replace("p", "_|_||_||_|__|");
            strTmp = strTmp.Replace("r", "_||_|_|_||__|");
            strTmp = strTmp.Replace("q", "_|_|_|_||__||");
            strTmp = strTmp.Replace("s", "_|_||_|_||__|");
            strTmp = strTmp.Replace("t", "_|_|_||_||__|");
            strTmp = strTmp.Replace("u", "_||__|_|_|_||");
            strTmp = strTmp.Replace("v", "_|__||_|_|_||");
            strTmp = strTmp.Replace("w", "_||__||_|_|_|");
            strTmp = strTmp.Replace("x", "_|__|_||_|_||");
            strTmp = strTmp.Replace("y", "_||__|_||_|_|");
            strTmp = strTmp.Replace("z", "_|__||_||_|_|");
            strTmp = strTmp.Replace("-", "_|__|_|_||_||");
            strTmp = strTmp.Replace("*", "_|__|_||_||_|");
            strTmp = strTmp.Replace("/", "_|__|__|_|__|");
            strTmp = strTmp.Replace("%", "_|_|__|__|__|");
            strTmp = strTmp.Replace("+", "_|__|_|__|__|");
            strTmp = strTmp.Replace(".", "_||__|_|_||_|");
            return strTmp;
        }
        public bool IsReusable
        {
            get
            {
                return false;
            }
        }
    }