asp.net core中使用Ftp上传下载文件

5年前 21,797 0

Microsoft has a C# example of uploading file to FTP server in MSDN https://msdn.microsoft.com/en-us/library/ms229715(v=vs.100).aspx and Microsoft docs https://docs.microsoft.com/en-us/dotnet/framework/network-programming/how-to-upload-files-with-ftp:

// Copy the contents of the file to the request stream.

StreamReader sourceStream = new StreamReader("testfile.txt");

byte[] fileContents = Encoding.UTF8.GetBytes(sourceStream.ReadToEnd());

sourceStream.Close();

request.ContentLength = fileContents.Length;

Stream requestStream = request.GetRequestStream();

requestStream.Write(fileContents, 0, fileContents.Length);

requestStream.Close();

It uses StreamReader to read a string from a text file, then encode the string to bytes and upload.

This document’s title has a general title “Upload Files with FTP". However, this approach with StreamReader only works with text file. If the above code is used to upload a binary file, like a picture, the uploaded file on FTP server becomes corrupted. The general options are:

1. Call File.ReadAllBytes to read the bytes, and write to request stream:

byte[] fileContents = File.ReadAllBytes(filePath);

using (Stream requestStream = request.GetRequestStream())

{

requestStream.Write(fileContents, 0, fileContents.Length);

}

2. Use FileStream to read the file, and copy the file stream to request stream:

public static async Task<FtpStatusCode> FtpUploadAsync(string uri, string userName, string password, string filePath)

{

FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uri);

request.Method = WebRequestMethods.Ftp.UploadFile;

request.Credentials = new NetworkCredential(userName, password);

// request.UsePassive is true by default.

using (FileStream fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read))

using (Stream requestStream = request.GetRequestStream())

{

await fileStream.CopyToAsync(requestStream);

}

using (FtpWebResponse response = (FtpWebResponse)await request.GetResponseAsync())

{

return response.StatusCode;

}

3. Use WebClient, which wraps all the above work flow:

public static async Task FtpUploadAsync(string uri, string userName, string password, string filePath)

{

using (WebClient webClient = new WebClient())

{

webClient.Credentials = new NetworkCredential(userName, password);

await webClient.UploadFileTaskAsync(uri, WebRequestMethods.Ftp.UploadFile, filePath);

}

3 comments

Hi,

Great stuff !. It was nicely explained and very useful. Thanks a lot.

Seb.

Sebastian D - Tuesday, February 5, 2019 3:47:19 AM
Uploading a file to an FTP server fails.

I have a small C# winform in which I generate some text files and then move them to an ftp server. When I try to move them to the production server it fails under

The remote server returned an error: (530) Not logged in.

If I log in to the ftp via cmd/ftp with the same ftp address, username and password, everything is ok. I also installed a local ftp server on my machine and tested it to see if perhaps my code is generating the error, but locally it works like a charm, I have the problem only with the production ftp server. Below is my code to connect and upload the files to the ftp server:

string[] FileName = Directory.GetFiles(outputpath);

foreach (string txtFile in FileName)
{
FileInfo toUpload = new FileInfo(txtFile);

FtpWebRequest request = (FtpWebRequest)WebRequest.Create("ftp://" + tbFTPAddress.Text + @"//" + toUpload.Name);

request.Credentials = new NetworkCredential(tbFTPUserName.Text.Trim(), tbFTPPassword.Text.Trim());

request.Method = WebRequestMethods.Ftp.UploadFile;

Stream ftpStream = request.GetRequestStream();
FileStream file = File.OpenRead(txtFile);

int length = 1024;
byte[] buffer = new byte[length];
int bytesRead = 0;

try
{
do
{
bytesRead = file.Read(buffer, 0, length);
ftpStream.Write(buffer, 0, bytesRead);
}
while (bytesRead != 0);

file.Close();
ftpStream.Close();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message, "Error encountered!", MessageBoxButtons.OK, MessageBoxIcon.Error);
}
finally
{
if (file != null) file.Close();
if (ftpStream != null) ftpStream.Close();
}
}
The error comes at: Stream ftpStream = request.GetRequestStream();

Any ideas?

Thanks!

Outlook Support - Thursday, April 18, 2019 3:23:57 AM
hello. im working in winform.
i have a problem in the same line but th exception is: System.Net.WebException: 'No se puede resolver el nombre remoto: 'pruebaftp.pagexyz.com'' i´ve try all ways the uri and its ok.. what could hapen?

danie avila - Friday, April 26, 2019 11:12:36 AM