private async Task Download(Stream downloadStream, FileStream fileStream, DownloadFile downloadFile)
{
int bufferSize = 1024 * 1024 * 100; //100M缓存
byte[] buffer = new byte[bufferSize];
long position = downloadFile.RangeBegin;
int readLength = 0;
try
{
decimal downloadSpeed = 0; //下载速度
var beginSecond = DateTime.Now.Second; //当前时间秒
while ((readLength = await downloadStream.ReadAsync(buffer, 0, buffer.Length)) != 0)
{
position += readLength;
downloadSpeed += readLength;
fileStream.Write(buffer, 0, readLength);
if (position != downloadFile.Length)
{
downloadFile.RangeBegin = position;
int appendLength = downloadFile.AppendFileStream(fileStream);
await fileStream.FlushAsync();
fileStream.Position -= appendLength;
}
var endSecond = DateTime.Now.Second;
if (endSecond != beginSecond)//计算速度
{
downloadSpeed = downloadSpeed / (endSecond - beginSecond);
this.OnDownloadSpeedChanged(new SpeedChangedArgs((float)(downloadSpeed / 1024)));
beginSecond = DateTime.Now.Second;
downloadSpeed = 0;//清空
}
this.OnDownloadProgressChanged(new ProgressChangedArgs(readLength, downloadFile.RangeBegin, downloadFile.Length == null ? -1 : downloadFile.Length.Value));
}
}
catch (Exception ex)
{
this.OnDownloadError(new ErrorArgs(ex.Message));
}
}