10

我正在尝试使用FtpWebRequest.

private void DownloadFile(string userName, string password, string ftpSourceFilePath, string localDestinationFilePath)
{
    int bytesRead = 0;
    byte[] buffer = new byte[1024];

    FtpWebRequest request = CreateFtpWebRequest(ftpSourceFilePath, userName, password, true);
    request.Method = WebRequestMethods.Ftp.DownloadFile;

    Stream reader = request.GetResponse().GetResponseStream();
    BinaryWriter writer = new BinaryWriter(File.Open(localDestinationFilePath, FileMode.CreateNew));

    while (true)
    {
        bytesRead = reader.Read(buffer, 0, buffer.Length);

        if (bytesRead == 0)
            break;

        writer.Write(buffer, 0, bytesRead);
    }        
}

它使用CreateFtpWebRequest我创建的这种方法：

private FtpWebRequest CreateFtpWebRequest(string ftpDirectoryPath, string userName, string password, bool keepAlive = false)
{
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(new Uri(ftpDirectoryPath));

    //Set proxy to null. Under current configuration if this option is not set then the proxy that is used will get an html response from the web content gateway (firewall monitoring system)
    request.Proxy = null;

    request.UsePassive = true;
    request.UseBinary = true;
    request.KeepAlive = keepAlive;

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

    return request;
}

它下载它。但信息总是被破坏。有谁知道发生了什么？

4

2 回答 2

26

刚刚想通了：

    private void DownloadFile(string userName, string password, string ftpSourceFilePath, string localDestinationFilePath)
    {
        int bytesRead = 0;
        byte[] buffer = new byte[2048];

        FtpWebRequest request = CreateFtpWebRequest(ftpSourceFilePath, userName, password, true);
        request.Method = WebRequestMethods.Ftp.DownloadFile;

        Stream reader = request.GetResponse().GetResponseStream();
        FileStream fileStream = new FileStream(localDestinationFilePath, FileMode.Create);

        while (true)
        {
            bytesRead = reader.Read(buffer, 0, buffer.Length);

            if (bytesRead == 0)
                break;

            fileStream.Write(buffer, 0, bytesRead);
        }
        fileStream.Close();       
    }

不得不改用 FileStream 。

于 2012-09-20T20:25:07.963 回答
14

最简单的方法

使用 .NET 框架从 FTP 服务器下载文件的最简单方法是使用WebClient.DownloadFile方法：

WebClient client = new WebClient();
client.Credentials = new NetworkCredential("username", "password");
client.DownloadFile(
    "ftp://ftp.example.com/remote/path/file.zip", @"C:\local\path\file.zip");

高级选项

使用FtpWebRequestclass，如果您只需要更大的控制，则WebClient该类不提供（如TLS/SSL 加密、进度监控、ascii/文本传输模式、恢复传输等）。一种简单的方法，就是将 FTP 响应流复制到FileStreamusingStream.CopyTo方法：

FtpWebRequest request =
    (FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/remote/path/file.zip");
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.DownloadFile;

using (Stream ftpStream = request.GetResponse().GetResponseStream())
using (Stream fileStream = File.Create(@"C:\local\path\file.zip"))
{
    ftpStream.CopyTo(fileStream);
}

进度监控

如果您需要监控下载进度，您必须自己按块复制内容：

FtpWebRequest request =
    (FtpWebRequest)WebRequest.Create("ftp://ftp.example.com/remote/path/file.zip");
request.Credentials = new NetworkCredential("username", "password");
request.Method = WebRequestMethods.Ftp.DownloadFile;

using (Stream ftpStream = request.GetResponse().GetResponseStream())
using (Stream fileStream = File.Create(@"C:\local\path\file.zip"))
{
    byte[] buffer = new byte[10240];
    int read;
    while ((read = ftpStream.Read(buffer, 0, buffer.Length)) > 0)
    {
        fileStream.Write(buffer, 0, read);
        Console.WriteLine("Downloaded {0} bytes", fileStream.Position);
    }
}

有关 GUI 进度 (WinForms ProgressBar)，请参阅：
FtpWebRequest FTP 下载与 ProgressBar

下载文件夹

如果要从远程文件夹下载所有文件，请参阅
C# 通过 FTP 下载所有文件和子目录。

于 2017-07-12T06:40:38.807 回答