download file from web server in asp.net c# to client's pc

Question

I am trying to download a file from the server to a folder that the client chooses onto their machine. But I keep getting the error could not find part of the path

For example the DownloadLocation could be C:/myfolder

Code:

FileName = comp.DownloadLocation + "/" + "/purchase" + ".csv";
regularfilename = "purchase.csv";
byte[] buffer;
using (FileStream fileStream = new FileStream(FileName, FileMode.Open))
{
    int fileSize = (int)fileStream.Length;
    buffer = new byte[fileSize];
    fileStream.Read(buffer, 0, (int)fileSize);
}

Response.Clear();
Response.Buffer = true;
Response.BufferOutput = true;
Response.ContentType = "application/x-download";
Response.AddHeader("Content-Disposition", "attachment; filename=" + regularfilename);
Response.CacheControl = "public";
Response.OutputStream.Write(buffer, 0, buffer.Length);
Response.Flush();  
Response.Clear();
Response.End();

This might help: http://www.codeproject.com/Tips/730360/How-to-Conditionally-Return-a-Binary-File-from-a — B. Clay Shannon-B. Crow Raven, Jan 06 '16 at 16:38

score 0 · Answer 1 · answered Jan 06 '16 at 16:39

0

Possibly not the answer however this is something you should definitely check:

FileName = comp.DownloadLocation + "/" + "/purchase" + ".csv";

You probably want to remove the / before purchase or drop the + "/" + completely as that's going to build up a path in the format:

"somepath//purchase.csv"

May well be casuing your issue. See if it makes a difference.

answered Jan 06 '16 at 16:39

Richard Pearson

31
1
2

Didn't make a difference – user123456789 Jan 06 '16 at 16:41

score 0 · Answer 2 · answered Jan 06 '16 at 16:41

If you need a client app to check the Web API server to see if the server's version of a file is newer than the version the client has, you can set up the server to do so by performing these steps:

Add the appropriate method to a Repository Interface, such as:

HttpResponseMessage GetCervezaBeberUpdate(string clientVersion);

Add this to the corresponding Controller class (where the Controller name is "HenryFieldingController"):

[Route("api/HenryFielding/GetUpdatedCervezaBeber")]
public HttpResponseMessage GetUpdate(string clientVersion)
{
    return _tomJonesRepository.GetCervezaBeberUpdate(clientVersion);
}

Add the appropriate method to the concrete Repository class, such as:

public HttpResponseMessage GetCervezaBeberUpdate(string clientVersion)
{
    var binaryFilePath = HostingEnvironment.MapPath(@"~\App_Data\CervezaBeber.exe");
    FileVersionInfo currentVersion = FileVersionInfo.GetVersionInfo(binaryFilePath);
    if (!ServerFileIsNewer(clientVersion, currentVersion))
    {
        result = new HttpResponseMessage(HttpStatusCode.NoContent);
    }
    else
    {
        var stream = new FileStream(binaryFilePath, FileMode.Open);
        HttpResponseMessage result = new HttpResponseMessage(HttpStatusCode.OK);
        result.Content = new StreamContent(stream);
        result.Content.Headers.ContentType =
            new MediaTypeHeaderValue("application/octet-stream");
    }
    return result;
}

Also add the method in that Repository class that GetCervezaBeberUpdate() calls:

private bool ServerFileIsNewer(string clientFileVersion, FileVersionInfo serverFile)
{
    Version client = new Version(clientFileVersion);
    Version server = new Version(string.Format("{0}.{1}.{2}.{3}", serverFile.FileMajorPart, serverFile.FileMinorPart, serverFile.FileBuildPart, serverFile.FilePrivatePart));
    return server > client;
}

Now the client can call this by passing a URI like this to the server:

http://<servername>:<portnumber>/api/
<controllername>?clientVersion=<clientversionquad>

Or, for a more literal example, in the event your server's name is "Platypus", the port to use is 4242, the Controller is named HenryFieldingController, and the version of the file the client currently has is 3.1.4.1:

http://Platypus:4242/api/HenryFielding?clientVersion=3.1.4.1

As a free-as-in-beer (you/I wish!) premium, here's some code the client can use to save the server's response to a file (passing this a URI such as shown above):

private void DownloadTheFile(string uri)
{
    var outputFileName = "Platypus.exe";
    var webRequest = (HttpWebRequest)WebRequest.Create(uri);
    var webResponse = (HttpWebResponse)webRequest.GetResponse();
    string statusCode = webResponse.StatusCode.ToString();
    // From here on (including the CopyStream() method) derived from Jon Skeet's 
    // answer at http://stackoverflow.com/questions/411592/how-do-i-save-a-stream-to-a-file
    if (statusCode == "NoContent")
    {
        MessageBox.Show("You already have the newest available version.");
    }
    else
    {
        var responseStream = webResponse.GetResponseStream();
        using (Stream file = File.Create(outputFileName))
        {
            CopyStream(responseStream, file);
            MessageBox.Show(string.Format("New version downloaded to {0}", outputFileName));
        }
    }
}

public static void CopyStream(Stream input, Stream output)
{
    byte[] buffer = new byte[8 * 1024];
    int len;
    while ((len = input.Read(buffer, 0, buffer.Length)) > 0)
    {
        output.Write(buffer, 0, len);
    }
}

download file from web server in asp.net c# to client's pc

2 Answers2