BiliRanking.Core.Download.HttpDownloadClient.DownloadInternal C# (CSharp) Method

        void DownloadInternal(object obj)
        {
            if (this.Status != DownloadStatus.Waiting)
            {
                return;
            }

            HttpWebRequest webRequest = null;
            HttpWebResponse webResponse = null;
            Stream responseStream = null;
            MemoryStream downloadCache = null;
            this.lastStartTime = DateTime.Now;

            try
            {

                if (!HasChecked)
                {
                    string filename = string.Empty;
                    CheckUrlAndFile(out filename);
                }

                this.EnsurePropertyValid();

                // Set the status.
                this.Status = DownloadStatus.Downloading;

                // Create a request to the file to be  downloaded.
                webRequest = DownloaderHelper.InitializeHttpWebRequest(this);

                // Specify the block to download.
                if (EndPoint != int.MaxValue)
                {
                    webRequest.AddRange(StartPoint + DownloadedSize, EndPoint);
                }
                else
                {
                    webRequest.AddRange(StartPoint + DownloadedSize);
                }

                // Retrieve the response from the server and get the response stream.
                webResponse = (HttpWebResponse)webRequest.GetResponse();

                responseStream = webResponse.GetResponseStream();

                // Cache data in memory.
                downloadCache = new MemoryStream(this.MaxCacheSize);

                byte[] downloadBuffer = new byte[this.BufferSize];

                int bytesSize = 0;
                CachedSize = 0;
                int receivedBufferCount = 0;

                // Download the file until the download is paused, canceled or completed.
                while (true)
                {

                    // Read a buffer of data from the stream.
                    bytesSize = responseStream.Read(downloadBuffer, 0, downloadBuffer.Length);

                    // If the cache is full, or the download is paused, canceled or
                    // completed, write the data in cache to local file.
                    if (this.Status != DownloadStatus.Downloading
                        || bytesSize == 0
                        || this.MaxCacheSize < CachedSize + bytesSize)
                    {

                        try
                        {
                            // Write the data in cache to local file.
                            WriteCacheToFile(downloadCache, CachedSize);

                            this.DownloadedSize += CachedSize;

                            // Stop downloading the file if the download is paused,
                            // canceled or completed.
                            if (this.Status != DownloadStatus.Downloading
                                || bytesSize == 0)
                            {
                                break;
                            }

                            // Reset cache.
                            downloadCache.Seek(0, SeekOrigin.Begin);
                            CachedSize = 0;
                        }
                        catch (Exception ex)
                        {
                            // Fire the DownloadCompleted event with the error.
                            this.OnDownloadCompleted(
                                new DownloadCompletedEventArgs(
                                    null,
                                    this.DownloadedSize,
                                    this.TotalSize,
                                    this.TotalUsedTime,
                                    ex));
                            return;
                        }

                    }

                    // Write the data from the buffer to the cache in memory.
                    downloadCache.Write(downloadBuffer, 0, bytesSize);

                    CachedSize += bytesSize;

                    receivedBufferCount++;

                    // Fire the DownloadProgressChanged event.
                    if (receivedBufferCount == this.BufferCountPerNotification)
                    {
                        InternalDownloadProgressChanged(CachedSize);
                        receivedBufferCount = 0;
                    }
                }

                // Update the used time when the current doanload is stopped.
                usedTime = usedTime.Add(DateTime.Now - lastStartTime);

                // Update the status of the client. Above loop will be stopped when the
                // status of the client is pausing, canceling or completed.
                if (this.Status == DownloadStatus.Pausing)
                {
                    this.Status = DownloadStatus.Paused;
                }
                else if (this.Status == DownloadStatus.Canceling)
                {
                    this.Status = DownloadStatus.Canceled;
                }
                else
                {
                    this.Status = DownloadStatus.Completed;
                    return;
                }

            }
            catch (Exception ex)
            {
                // Fire the DownloadCompleted event with the error.
                this.OnDownloadCompleted(
                    new DownloadCompletedEventArgs(
                        null,
                        this.DownloadedSize,
                        this.TotalSize,
                        this.TotalUsedTime,
                        ex));
                return;
            }
            finally
            {
                // When the above code has ended, close the streams.
                if (responseStream != null)
                {
                    responseStream.Close();
                }
                if (webResponse != null)
                {
                    webResponse.Close();
                }
                if (downloadCache != null)
                {
                    downloadCache.Close();
                }
            }
        }