private void ReadCallBack(IAsyncResult asyncResult)
        {
            if (this.IsCancled)
            {
                this.ReleaseSource();
                return;
            }

            try
            {

                //RequestState myRequestState = (RequestState)asyncResult.AsyncState;
                Stream responseStream = myRequestState.streamResponse;
                int read = responseStream.EndRead(asyncResult);
                // Read the HTML page and then print it to the console.
                if (read > 0)
                {
                    //string contentType = myRequestState.response.ContentType;
                    //string encodeName = contentType.Substring(contentType.IndexOf("charset") + 8);
                    //Encoding ecd = Encoding.GetEncoding(encodeName);
                    //myRequestState.requestData.Append(ecd.GetString(myRequestState.BufferRead, 0, read));
                    myRequestState.requestData.Append(Encoding.UTF8.GetString(myRequestState.BufferRead, 0, read));
                    IAsyncResult asynchronousResult = responseStream.BeginRead(myRequestState.BufferRead, 0, BUFFER_SIZE, new AsyncCallback(ReadCallBack), myRequestState);
                    return;
                }
                else
                {
                    // 数据从网络上读取完毕,此时需要完成两个工作:
                    // 1. 检查数据中是否有自定义的异常信息
                    // 2.如果没有异常信息,调用完成事件
                    string str = myRequestState.requestData.ToString();

                    if (myErrorParser != null)
                    {
                        if (myErrorParser.HasError(str))
                        {
                            HttpException he = new HttpException();
                            he.Message = myErrorParser.GetErrorMessage(str);
                            this.RaiseException(he);
                            //if (this.AcceptException != null)
                            //    this.AcceptException(he);
                        }
                        else
                            this.RaiseEvents();

                    }
                    else
                        RaiseEvents();

                }

            }
            #region 异常处理

            catch (Exception e)
            {
                this.RaiseException(e);
                //if (this.AcceptException != null)
                //{
                //    HttpException he = new HttpException();
                //    he.Message = e.Message;
                //    this.AcceptException(he);

                //}
            }

            #endregion

            ReleaseSource();
        }
 void RaiseException(Exception e)
 {
     if (this.AcceptException != null)
     {
         HttpException he = new HttpException();
         he.Message = e.Message;
         //this.AcceptException(he);
     }
 }