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FtpWebRequest下载文件大小不正确

ftpwebresponse ftpwebrequest ftp c#

3

Paul Michaels · 技术社区 · 14 年前

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

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

        request.Method = WebRequestMethods.Ftp.DownloadFile;
        request.Credentials = new NetworkCredential(userName, password);                

        using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
        using (Stream responseStream = response.GetResponseStream())
        using (StreamReader reader = new StreamReader(responseStream))
        using (StreamWriter destination = new StreamWriter(destinationFile))
        {
            destination.Write(reader.ReadToEnd());
            destination.Flush();
        }

        destination.Write(reader.ReadToEnd());
        destination.Flush();

有人能对可能的错误提出什么看法吗?

1 回复 | 直到 14 年前

1

11

Community ahmed 7 年前

StreamReader 和 StreamWriter 使用字符数据,所以您将流从字节解码为字符,然后再将其编码回字节。dll文件包含二进制数据,因此这种往返转换将引入错误。您想直接从 responseStream 对象并写入 FileStream 流作者

如果您使用的是.NET4.0,那么 Stream.CopyTo This StackOverflow question 有一个复制流的好方法:

public static void CopyStream(Stream input, Stream output)
{
    byte[] buffer = new byte[32768];
    while (true)
    {
        int read = input.Read(buffer, 0, buffer.Length);
        if (read <= 0)
            return;
        output.Write(buffer, 0, read);
    }
}

因此,您的代码如下所示:

using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
using (Stream responseStream = response.GetResponseStream())
using (FileStream destination = File.Create(destinationFile))
{
    CopyStream(responseStream, destination);
}