private long CheckFile(DownloadFileRangeState state)
{
long startPos = 0;
if (File.Exists(state.TempPath))
{
state.FileStream = File.OpenWrite(state.TempPath);
startPos = state.FileStream.Length;
state.FileStream.Seek(startPos, SeekOrigin.Current);
}
else
{
try
{
string direName = Path.GetDirectoryName(state.TempPath);
if (!Directory.Exists(direName))
{
Directory.CreateDirectory(direName);
}
state.FileStream = new FileStream(state.TempPath, FileMode.Create);
}
catch (Exception e)
{
state.Exception = e;
startPos = -1;
state.Close();
}
}
return(startPos);
}
private void WriteFile(DownloadFileRangeState state, long startPos)
{
var bytesReceived = startPos;
byte[] bytes = new byte[1024];
bool isDownloadCompleted = false;
var totalBytesReceived = state.Respone.ContentLength + startPos;
int readSize = state.Stream.Read(bytes, 0, 1024);
while (readSize > 0 && state.IsRangeDownload)
{
if (state == null || state.FileStream == null)
{
break;
}
lock (state.FileStream)
{
if (DownloadProgressChangedEx != null)
{
DownloadProgressChangedEx(this, new DownloadProgressChangedEventArgsEx(bytesReceived, totalBytesReceived, ((float)bytesReceived / totalBytesReceived), state.UserState));
}
state.FileStream.Write(bytes, 0, readSize);
bytesReceived += readSize;
if (totalBytesReceived != 0 && bytesReceived >= totalBytesReceived)
{
try
{
state.Close();
if (File.Exists(state.Path))
{
File.Delete(state.Path);
}
File.Move(state.TempPath, state.Path);
isDownloadCompleted = true;
state.Done(isDownloadCompleted);
}
catch (Exception e)
{
state.Exception = e;
state.Done(false);
}
}
else
{
readSize = state.Stream.Read(bytes, 0, 1024);
}
}
}
if (!isDownloadCompleted)
{
state.Exception = new Exception("Request for early closure");
}
}
public void DownloadFileRange(string url, string path, object userState)
{
if (_state != null && _state.IsRangeDownload)
{
return;
}
_state = new DownloadFileRangeState(path, userState, this);
_state.OnCompleted = () => DownloadFileCompletedEx;
_state.IsRangeDownload = true;
long startPos = CheckFile(_state);
if (startPos == -1)
{
return;
}
try
{
_state.Request = (HttpWebRequest)GetWebRequest(new Uri(url));
_state.Request.ReadWriteTimeout = _timeOut;
_state.Request.Timeout = _timeOut;
_state.Respone = _state.Request.GetResponse();
_state.Stream = _state.Respone.GetResponseStream();
if (_state.Respone.ContentLength == startPos)
{
_state.Close();
File.Move(_state.TempPath, _state.Path);
_state.Done(true);
return;
}
if (startPos > 0)
{
_state.Request.AddRange((int)startPos);
}
long totalBytesReceived = _state.Respone.ContentLength + startPos;
long bytesReceived = startPos;
if (totalBytesReceived != 0 && bytesReceived >= totalBytesReceived)
{
_state.Close();
try
{
if (File.Exists(_state.Path))
{
File.Delete(_state.Path);
}
File.Move(_state.TempPath, _state.Path);
}
catch (Exception e)
{
_state.Exception = e;
_state.Close();
}
}
else
{
WriteFile(_state, startPos);
}
}
catch (Exception e)
{
_state.Exception = e;
throw new Exception($"'DownloadFileRange' This function has an internal exception : { e.Message } .", e.InnerException);
}
finally
{
if (_state != null)
{
_state.Close();
}
}
}
