How do I download zip file in C#?

Question

I use HTTP GET that downloads a zip file in a browser, something like https://example.com/up/DBID/a/rRID/eFID/vVID (not the exact url)

Now, when I try to do the same download in C# code(same GET method as above) for a desktop application, the zip file downloaded is not a valid archive file. When I opened this file in notepad, it was some HTML page.

I think I'm not setting some header correctly. I looked around for examples. I'd found several wrt uploads, but did not see anything for downloads.

Code:

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "GET";
request.ContentType = "application/zip";
try
{
    HttpWebResponse res = (HttpWebResponse)request.GetResponse();
    using (StreamReader sr = new StreamReader(res.GetResponseStream(), System.Text.Encoding.Default))
    {
        StreamWriter oWriter = new StreamWriter(@"D:\Downloads\1.zip");
        oWriter.Write(sr.ReadToEnd());
        oWriter.Close();
    }
    res.Close();
}
catch (Exception ex)
{
}

Answer 1

It's mainly because you use a StreamWriter : TextWriter to handle a binary Zip file. A StreamWriter expects text and will apply an Encoding. And even the simple ASCII Encoder might try to 'fix' what it thinks are invalid line-endings.

You can replace all your code with:

  using (var client = new WebClient())
  {
    client.DownloadFile("http://something",  @"D:\Downloads\1.zip");
  }

Note that for new code you should look at HttpClient instead of WebClient.
And then don't use using( ) { }

Answer 2

You could just use WebClient for a 2-liner:

using(WebClient wc = new WebClient())
{
   wc.DownloadFile(url, @"D:\Downloads\1.zip");
}