Stream分段写入提示“请求被中止: 请求已被取消”
为了实现一个文件上传的功能，我将上传的文件分段写入Stream类的对象，如果文件过大（貌似大于3M）就会提示“请求被中止: 请求已被取消”，如果不分段的话就能成功上传不提示任何问题。看代码

                int UploadNum=0;

                Stream dataStream = request.GetRequestStream();

                UploadNum = postData.Length / 5000;

                System.Threading.Timer FileTm = new System.Threading.Timer(CalculateSpeedTime, null, 0, 1500);

                for (int i = 0; i <= UploadNum; i++)

                {

                    if (i == UploadNum)

                    {

                        dataStream.Write(postData, i * 5000, postData.Length - i * 5000);

                        TempDataSize += postData.Length - i * 5000;

                    }

                    else

                    {

                        dataStream.Write(postData, i * 5000, 5000);//这里会报错

                        TempDataSize += 5000;

                    }

                    setprogressbar(true, (i * 5000.0 / postData.Length) * 100.0, UploadSpeed);

                }

                dataStream.Close();