public static DownloadData Create(string url, string destFolder, IWebProxy proxy)
{
// This is what we will return
DownloadData downloadData = new DownloadData();
downloadData.proxy = proxy;
long urlSize = downloadData.GetFileSize(url);
downloadData.size = urlSize;
WebRequest req = downloadData.GetRequest(url);
try
{
downloadData.response = (WebResponse)req.GetResponse();
}
catch (Exception e)
{
throw new ArgumentException(String.Format(
"Error downloading \"{0}\": {1}", url, e.Message), e);
}
// Check to make sure the response isn't an error. If it is this method
// will throw exceptions.
ValidateResponse(downloadData.response, url);
// Take the name of the file given to use from the web server.
String fileName = System.IO.Path.GetFileName(downloadData.response.ResponseUri.ToString());
String downloadTo = Path.Combine(destFolder, fileName);
// If we don't know how big the file is supposed to be,
// we can't resume, so delete what we already have if something is on disk already.
if (!downloadData.IsProgressKnown && File.Exists(downloadTo))
{
File.Delete(downloadTo);
}
if (downloadData.IsProgressKnown && File.Exists(downloadTo))
{
// We only support resuming on http requests
if (!(downloadData.Response is HttpWebResponse))
{
File.Delete(downloadTo);
}
else
{
// Try and start where the file on disk left off
downloadData.start = new FileInfo(downloadTo).Length;
// If we have a file that's bigger than what is online, then something
// strange happened. Delete it and start again.
if (downloadData.start > urlSize)
{
File.Delete(downloadTo);
}
else if (downloadData.start < urlSize)
{
// Try and resume by creating a new request with a new start position
downloadData.response.Close();
req = downloadData.GetRequest(url);
((HttpWebRequest)req).AddRange((int)downloadData.start);
downloadData.response = req.GetResponse();
if (((HttpWebResponse)downloadData.Response).StatusCode != HttpStatusCode.PartialContent)
{
// They didn't support our resume request.
File.Delete(downloadTo);
downloadData.start = 0;
}
}
}
}
return(downloadData);
}