HttpHelper有时候会报【本次请求并未返回任何数据】

Kenney

HttpHelper有时候会报【本次请求并未返回任何数据】
这个怎么破？
我是读取人家网站的图片验证码 使用OCR解析，有没有了解这个的朋友帮忙分析下

[C#] 纯文本查看 复制代码

 #region have a try
            //try
            string sCookie = string.Empty;
            string _Referer = string.Empty;
            HttpHelper http = new HttpHelper();
            HttpItem item = new HttpItem()
            {
                URL = "http://www.ems.com.cn/ems/order/singleQuery_t",
                Allowautoredirect = false,
                Method = "GET",
            };
            HttpResult result = http.HttpRequest(item);
            _Referer = result.Html;
            sCookie = result.Cookie;
            item = new HttpItem()
            {
                URL = "http://www.ems.com.cn/ems/rand?d=0.3501349513942344",
                Method = "GET", 
                Cookie = sCookie,
                ResultType = ResultType.Byte,
                Referer = _Referer,
            };
            result = http.HttpRequest(item);
            if (result.ResultByte != null)
            {
                //MessageBox.Show(result.ResultByte.Length.ToString());
                MemoryStream ms = new MemoryStream(result.ResultByte);
                ms.Seek(0, SeekOrigin.Current);
                Bitmap bitmap = (Bitmap)Bitmap.FromStream(ms);

                pictureBox1.Image = Image.FromStream(new MemoryStream(result.ResultByte));

                #region OCR

                UnCodebase ud = new UnCodebase(bitmap);
                bitmap = ud.GrayByPixels();
                ud.ClearNoise(128, 2);

                pictureBox1.Image = bitmap;

                tessnet2.Tesseract ocr = new tessnet2.Tesseract();//声明一个OCR类
                ocr.SetVariable("tessedit_char_whitelist", "0123456789"); //设置识别变量，当前只能识别数字。
                ocr.Init(Application.StartupPath + @"\\tmpe", "eng", true); //应用当前语言包。注，Tessnet2是支持多国语的。语言包下载链接：[url]http://code.google.com/p/tesseract-ocr/downloads/list[/url]
                List<tessnet2.Word> OCRresult = ocr.DoOCR(bitmap, Rectangle.Empty);//执行识别操作
                string code = OCRresult[0].Text;

                #endregion

                item = new HttpItem()
                {
                    URL = "http://www.ems.com.cn/ems/order/singleQuery_t",
                    Method = "POST",
                    Postdata = string.Format("mailNum=BS025000854CN&checkCode={0}", code),
                    Cookie = sCookie,
                    Referer = _Referer,
                };
                result = http.HttpRequest(item);
                textBox1.Text = code;
                richTextBox1.Text = "读取成功 " + DateTime.Now;
                richTextBox1.Text += "\r\n" + result.Html;
                return bitmap;
            }
            else
            {
                richTextBox1.Text = result.Html;
            }
            return null;
            //end try

站长苏飞

这说明请求失败，没有返回任何内容