从FTP下载具有进度的文件 - TotalBytesToReceive总是-1？ [英] Download file from FTP with Progress - TotalBytesToReceive is always -1?

问题描述

文件正在下载，并且ProgressChanged事件正在调用，除了事件参数TotalBytesToReceive始终为-1。 TotalBytes增加了，但是我无法计算没有总数的百分比。

我想我可以通过其他ftp命令找到文件大小，但是我想知道为什么这样做不能实现，

我的代码：

  FTPClient request = new FTPClient （）; 
 request.Credentials = credentials; 
 request.DownloadProgressChanged + = new DownloadProgressChangedEventHandler（request_DownloadProgressChanged）; 
 //request.DownloadDataCompleted + = new DownloadDataCompletedEventHandler（request_DownloadDataCompleted）; 
 request.DownloadDataAsync（new Uri（folder + file））; 
 while（request.IsBusy）; 
  

....

  static void request_DownloadProgressChanged（object sender，DownloadProgressChangedEventArgs e）
 {
 if（e.TotalBytesToReceive == -1）
 {
 l.reportProgress（ - 1，FormatBytes（e.BytesReceived）+out of？）; 
} 
 else 
 {
 l.reportProgress（e.ProgressPercentage，Downloaded+ FormatBytes（e.BytesReceived）+out of+ FormatBytes（e.TotalBytesToReceive）+ （+ e.ProgressPercentage +％））; 
} 
} 
  

....

  class FTPClient：WebClient 
 {
保护覆盖WebRequest GetWebRequest（System.Uri地址）
 {
 FtpWebRequest req =（FtpWebRequest）base.GetWebRequest（address）; 
 req.UsePassive = false; 
 return req; 
 
 
 $ / code $ / pre 
 $ b $ p感谢。
 
解决方案
所以我有同样的问题。我通过首先检索文件大小来解决它。
  //获取用于与服务器通信的对象。 
 FtpWebRequest请求=（FtpWebRequest）WebRequest.Create（URL）; 
 request.Method = WebRequestMethods.Ftp.GetFileSize; 
 request.Credentials = networkCredential; 
 FtpWebResponse response =（FtpWebResponse）request.GetResponse（）; 
 
 Stream responseStream = response.GetResponseStream（）; 
 bytes_total = response.ContentLength; //这是一个int成员变量，用于以后存储
 Console.WriteLine（Fetch Complete，ContentLength {0}，response.ContentLength）; 
 response.Close（）; 
 
 webClient = new MyWebClient（）; 
 webClient.Credentials = networkCredential; ; 
 webClient.DownloadDataCompleted + = new DownloadDataCompletedEventHandler（FTPDownloadCompleted）; 
 webClient.DownloadProgressChanged + = new DownloadProgressChangedEventHandler（FTPDownloadProgressChanged）; 
 webClient.DownloadDataAsync（new Uri（URL））; 
  
然后在回调中进行数学运算。
 
 
 < pre $  private void FTPDownloadProgressChanged（object sender，DownloadProgressChangedEventArgs e）
 {
 progressBar.Value =（int）（（（float）e.BytesReceived /（float）bytes_total ）* 100.0）; 
} 
  




I am trying to download a file from an FTP server with a progress bar.

The file is downloading, and the ProgressChanged event is calling, except in the event args TotalBytesToReceive is always -1. TotalBytes increases, but I am unable to calculate the percentage without the total.

I imagine I could find the file size through other ftp commands, but I wonder why this doesn't work?

My code:

FTPClient request = new FTPClient();
request.Credentials = credentials;
request.DownloadProgressChanged += new DownloadProgressChangedEventHandler(request_DownloadProgressChanged);
//request.DownloadDataCompleted += new DownloadDataCompletedEventHandler(request_DownloadDataCompleted);
request.DownloadDataAsync(new Uri(folder + file));
while (request.IsBusy) ;

....

static void request_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
    if (e.TotalBytesToReceive == -1)
    {
        l.reportProgress(-1, FormatBytes(e.BytesReceived) + " out of ?" );
    }
    else
    {
        l.reportProgress(e.ProgressPercentage, "Downloaded " + FormatBytes(e.BytesReceived) + " out of " + FormatBytes(e.TotalBytesToReceive) + " (" + e.ProgressPercentage + "%)");
    }
}

....

class FTPClient : WebClient
{
    protected override WebRequest GetWebRequest(System.Uri address)
    {
        FtpWebRequest req = (FtpWebRequest)base.GetWebRequest(address);
        req.UsePassive = false;
        return req;
    }
}

Thanks.

解决方案

So I had the same issue. I got around it by retrieving the file size first.

        // Get the object used to communicate with the server.
        FtpWebRequest request = (FtpWebRequest)WebRequest.Create("URL");
        request.Method = WebRequestMethods.Ftp.GetFileSize;
        request.Credentials = networkCredential;
        FtpWebResponse response = (FtpWebResponse)request.GetResponse();

        Stream responseStream = response.GetResponseStream();
        bytes_total = response.ContentLength; //this is an int member variable stored for later
        Console.WriteLine("Fetch Complete, ContentLength {0}", response.ContentLength);
        response.Close();

        webClient = new MyWebClient();
        webClient.Credentials = networkCredential; ;
        webClient.DownloadDataCompleted += new DownloadDataCompletedEventHandler(FTPDownloadCompleted);
        webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(FTPDownloadProgressChanged);
        webClient.DownloadDataAsync(new Uri("URL"));

Then do the math in the callback.

private void FTPDownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)
{
     progressBar.Value = (int)(((float)e.BytesReceived / (float)bytes_total) * 100.0);
}

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