asp.net - 将图像上传到 FTP 时出现错误

Question

我在这个函数中遇到了很多不同的问题:

public static bool UploadToFTP(string strFileName, string strFolderName)
        {
            bool isUploaded = false;
            string strFilename = string.Empty;
            string strFtpURI = string.Empty;
            string strFtpUserId = string.Empty;
            string strFtpPassword = string.Empty;
            byte[] buffer = null;
            FileInfo oFileInfo = null;
            FileStream oFileStream = null;
            FtpWebRequest oFtpWebRequest = null;

            try
            {
                strFilename = strFileName;
                oFileInfo = new FileInfo(strFilename);
                strFtpURI = Constants.FtpUri;
                strFtpUserId = Constants.FtpUserID;
                strFtpPassword = Constants.FtpPassword;

                oFtpWebRequest = (FtpWebRequest)FtpWebRequest.Create(new Uri(strFtpURI + "/" + strFolderName + "/" + oFileInfo.Name));

                oFtpWebRequest.Credentials = new NetworkCredential(strFtpUserId, strFtpPassword);
                oFtpWebRequest.Proxy = null;
                oFtpWebRequest.KeepAlive = false;
                oFtpWebRequest.Method = WebRequestMethods.Ftp.UploadFile;
                oFtpWebRequest.UseBinary = true;
                oFtpWebRequest.ContentLength = oFileInfo.Length;

                int iBufferLength = 2084;

                buffer = new byte[iBufferLength];

                int iContentLength = 0;

                oFileStream = oFileInfo.OpenRead();

                try
                {
                    iContentLength = oFileStream.Read(buffer, 0, iBufferLength);

                    using (Stream oStream = oFtpWebRequest.GetRequestStream())
                    {
                        while (iContentLength != 0)
                        {
                            oStream.Write(buffer, 0, iContentLength);

                            iContentLength = oFileStream.Read(buffer, 0, iBufferLength);
                        }
                        isUploaded = true;
                        FtpUpload.TotalKBFilesUploaded =  FtpUpload.TotalKBFilesUploaded + (int)(oFileInfo.Length / 1000);
                    }
                }
                catch (Exception ex)
                {

                }
                finally
                {
                    if (oFtpWebRequest != null)
                    {
                        oFtpWebRequest.Abort();
                        oFtpWebRequest = null;
                    }

                    if (buffer != null)
                    {
                        buffer = null;
                    }

                    if (oFileStream != null)
                    {
                        oFileStream.Close();
                        oFileStream.Dispose();
                    }
                }
            }
            catch (Exception ex)
            {
            }
            finally
            {
                oFileInfo = null;
            }

            return isUploaded;
        }

这是将 1000 幅图像上传到 FTP，这种方法以多线程方式调用。

不同的错误是:

================================================== ======

消息:操作已超时

错误跟踪:在 System.Net.FtpWebRequest.CheckError() 在 System.Net.FtpWebRequest.GetRequestStream()

================================================== ======

错误信息:无法连接到远程服务器

错误跟踪:在 System.Net.FtpWebRequest.CheckError() 在 System.Net.FtpWebRequest.GetRequestStream()

================================================== ======

错误消息:基础连接已关闭:接收时发生意外错误。

错误跟踪:在 System.Net.FtpWebRequest.CheckError() 在 System.Net.FtpWebRequest.SyncRequestCallback(Object obj) 在 System.Net.CommandStream.Abort(Exception e) 在 System.Net.FtpWebRequest.FinishRequestStage(RequestStage stage) 在System.Net.FtpWebRequest.GetRequestStream()

================================================== ======

错误信息:无法向传输连接写入数据:连接尝试失败，因为连接方在一段时间后没有正确响应，或者由于连接的主机未能响应而建立的连接失败。

错误跟踪:在 System.Net.Sockets.NetworkStream.Write(Byte[] buffer, Int32 offset, Int32 size) at System.Net.FtpDataStream.Write(Byte[] buffer, Int32 offset, Int32 size)
================================================== ======

这些错误来自我从 LOG 文件中检索到的相同方法。

知道是什么原因造成的吗？或者我需要提供更多细节？

Answer 1

达到超时时会遇到以下异常:

Error Message:The underlying connection was closed: An unexpected error occurred on a receive.

如 msdn 文档中所述，超时的默认值是无限的，但 msdn 文档包含一个错误:
http://msdn.microsoft.com/fr-fr/library/vstudio/system.net.ftpwebrequest.timeout(v=vs.80).aspx

事实上，默认值为 100000 毫秒(1 分 40 秒)，因此您可以使用以下命令将超时值声明为无限:oFtpWebRequest.Timeout = -1;

http://www.sidesofmarch.com/index.php/archive/2012/04/06/damn-the-documentation-ftpwebrequest-timeout-default-value-is-not-infinite/