Question

我想从某个网址下载ZIP文件。当我打开浏览器并写入URL时，浏览器直接开始下载ZIP文件。但是我想要的是使用C＃代码自动执行此操作。

我尝试过以下代码：

private void btnDownload_Click(object sender, EventArgs e) {
  WebClient webClient = new WebClient();
  webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed); 
  webClient.DownloadFileAsync(new Uri("http://---/file.zip"), @"c:\file.zip");
}     

private void Completed(object sender, AsyncCompletedEventArgs e) {
  MessageBox.Show("Download completed!");
}

似乎下载工作正常，但当我检查下载的文件时，我发现它是 0 KB。

知道发生了什么事吗？

Answer 1

正如我所看到的，您的代码对应于已知的反模式Timer and Garbage Collector。

btnDownload_Click完成后，webClient变量无法访问，垃圾收集器会将其与其功能一起销毁。

试试这个：

private WebClient webClient = null;

private void btnDownload_Click(object sender, EventArgs e) {
  // Is file downloading yet?
  if (webClient != null)
    return;

  webClient = new WebClient();
  webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(Completed); 
  webClient.DownloadFileAsync(new Uri("http://---/file.zip"), @"c:\file.zip");
}     

private void Completed(object sender, AsyncCompletedEventArgs e) {
  webClient = null;
  MessageBox.Show("Download completed!");
}

现在`webClient是该类的成员，可以访问。然后垃圾收集器不会破坏它。

Answer 2

这有效：

WebClient webClient = new WebClient();
webClient.Headers.Add("Accept: text/html, application/xhtml+xml, */*");
webClient.Headers.Add("User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; WOW64; Trident/5.0)");
 webClient.DownloadFileAsync(new Uri("https://www.nseindia.com/content/historical/DERIVATIVES/2016/AUG/fo05AUG2016bhav.csv.zip"),"test1.zip");

Answer 3

您可以像这样轻松使用ZipFile类：

using System.IO.Compression;

    class Program
    {
        static void Main()
        {
        // Create a ZIP file from the directory "source".
        // ... The "source" folder is in the same directory as this program.
        // ... Use optimal compression.
        ZipFile.CreateFromDirectory("source", "destination.zip",
            CompressionLevel.Optimal, false);

        // Extract the directory we just created.
        // ... Store the results in a new folder called "destination".
        // ... The new folder must not exist.
        ZipFile.ExtractToDirectory("destination.zip", "destination");
        }
    }

请注意，这只是available from .Net Framework version 4.5以后......

Answer 4

我也有这个问题，但我找到了一个简单的解决方案我想从“https://tools.ietf.org/html/rfc4514”下载此Zip文件并提取它们。但webClient不能下载它。

我的解决方案：

第1步：将我的FileName从“D：\ update.zip”更改为“D：\ update.zi”webClient.DownloadFileAsync("http://sodco.ir/Choobkhat/Update/update.zip", "D:\\update.zi);

它将开始下载，下载完成后：

第2步：将update.zi重命名为update.zi p

File.Move("update.zi", "update.zip");

第3步：提取它们

ZipFile.ExtractToDirectory(Application.StartupPath + "\\update.zip", Application.StartupPath);

http://sodco.ir/Choobkhat/Update/update.zip

Answer 5

完整示例：Full sample at .Net Fiddle

public static bool DownloadFile(string filenameXML){
HttpWebRequest request;
HttpWebResponse response = null;
FileStream fs = null;
long startpoint = 0;
NewSourceFilePath=filenameXML;

fs = File.Create(NewSourceFilePath);
request = (HttpWebRequest)WebRequest.Create("http://---/file.zip");
request.KeepAlive = false;
request.ProtocolVersion = HttpVersion.Version11;
request.Method = "GET";
request.ContentType = "gzip";
request.Timeout=10000;
request.Headers.Add("xRange", "bytes " + startpoint + "-");
response = (HttpWebResponse)request.GetResponse();
Stream streamResponse = response.GetResponseStream();
byte[] buffer = new byte[1024];
int read;
while ((read = streamResponse.Read(buffer, 0, buffer.Length)) > 0){
fs.Write(buffer, 0, read);}
fs.Flush();fs.Close();
}

如何使用C＃从URL下载ZIP文件？

5 个答案: