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)
{
}

This is an unguessable 'it doesn't work' question. Post code, document what you see when you open the file in a hex viewer. — Hans Passant, Jan 22 '11 at 16:31

H H · Accepted Answer · 2019-10-18T23:08:18.930

43

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( ) { }

edited Oct 18 '19 at 23:08

answered Jan 22 '11 at 16:37

H H

263,252
30
330
514

Oh yes, I can see the same problem in there. – Al Kepp Jan 22 '11 at 16:40
+1 beat me - @Al: I tested this with a zip file and it works just fine, are you sure the file itself is not corrupted already? – BrokenGlass Jan 22 '11 at 16:45
WebClient also created the same type of zip file. – Merrin Jan 22 '11 at 16:47
@Merrin, if you mean "the same faulty Zip file" then you need to give (a lot) more information. – H H Jan 22 '11 at 16:48
1

I think the issue I'm facing is authentication to the service. And then I could probably use the webclient to download the file. – Merrin Jan 22 '11 at 17:00
@Merrin did you sort this out as i am having the same HTML zip problem? – Ashley Staggs Oct 29 '11 at 12:47
@AshleyStaggs Yes, for me I was not authenticated when I attempted to download. – Merrin Feb 22 '12 at 14:03
1

@HenkHolterman Oh my dear god, this answer just saved me **so** much time. Many thanks to you and Google who brought me here. – Mike G Jun 29 '12 at 14:55
@HenkHolterman Hi, I am trying to post a zip file from my app (Android is the client) to a IIS server (using C#.net for server side code). But my saved zip file at the server side on opening says it's an corrupted archive. Any pointers of what's wrong? I suspect that the header's are written too but AFAIK I don't think that the `HTTP` POST method from my client app is sending any header(s) just a zip file instead. :| – beerBear Feb 01 '13 at 06:19
@codebreaker - SO is not a forum, if you can't find an exiting answer then post a new question. – H H Feb 01 '13 at 07:58
@HenkHolterman Please see [my ques](http://stackoverflow.com/questions/14642246/saved-zip-file-gets-corrupted-from-an-android-app-to-an-iis-server). Thanks :) – beerBear Feb 01 '13 at 08:25
1

@HenkHolterman thanks buddy. you saved my life. its working fine :) – Arul Sidthan Oct 19 '15 at 14:46
How to run it if proxy authentication is required? – Faizan Mubasher May 16 '18 at 10:49
Don't ask questions in comments. Search for it and post a new Question if necessary. – H H May 16 '18 at 16:29

score 8 · Answer 2 · edited Aug 30 '12 at 20:00

8

You could just use WebClient for a 2-liner:

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

edited Aug 30 '12 at 20:00

Bek Raupov

3,782
3
24
42

answered Jan 22 '11 at 16:42

BrokenGlass

158,293
28
286
335

Short and simple. I like that kind of programming. +1 for you – Al Kepp Jan 22 '11 at 16:50
2

@anvarbekraupov: I am using a `using` statement - look harder – BrokenGlass Jul 30 '12 at 13:25
@BrokenGlass, replaced my downgrade with +1, apologies! – Bek Raupov Aug 30 '12 at 20:01

score 3 · Answer 3 · answered Sep 12 '19 at 12:09

You can also use System.Net.Http.HttpClient

using (HttpClient client = new HttpClient())
{
        using (HttpResponseMessage response = await client.GetAsync(downloadURL))
        {
             using(var stream = await response.Content.ReadAsStreamAsync())
             {
                  using(Stream zip = FileManager.OpenWrite(ZIP_PATH))
                  {
                       stream.CopyTo(zip);
                  }
             }
        }
}

KyleMit · Answer 4 · 2020-07-12T19:46:40.327

Expanding on Ruben's answer which uses HttpClient instead of WebClient, you can add as an extension method like this:

using System.IO;
using System.Net.Http;
using System.Threading.Tasks;

public static class Extensions
{
    public static async Task DownloadFile (this HttpClient client, string address, string fileName) {
        using (var response = await client.GetAsync(address))
        using (var stream = await response.Content.ReadAsStreamAsync())
        using (var file = File.OpenWrite(fileName)) {
            stream.CopyTo(file);
        }
    }
}

And then use like this:

var archivePath = "https://api.github.com/repos/microsoft/winget-pkgs/zipball/";
using (var httpClient = new HttpClient())
{
    await httpClient.DownloadFile(archivePath, "./repo.zip");
}

How do I download zip file in C#?

4 Answers4

Linked