/// <summary>
/// 保存文件下载的配置信息，包括总字节数、已下载字节数、下载队列信息
/// </summary>
/// <param name="configFile"></param>
/// <param name="downloadSize"></param>
/// <param name="totalSize"></param>
/// <param name="downloadQueue"></param>
public static void SaveConfig(string configFile, long downloadSize, long totalSize, Queue <ThreadDownloadInfo> downloadQueue)
{
var config = new FileDownloadConfig()
{
DownloadSize = downloadSize,
TotalSize = totalSize,
DownloadQueue = downloadQueue
};
Utils.WriteObjectToDisk(configFile, config);
}
public async void StartDownload(FileDownloadInfo info)
{
if (string.IsNullOrEmpty(info.DownLoadUrl))
{
throw new Exception("下载地址不能为空！");
}
if (!info.DownLoadUrl.ToLower().StartsWith("http://") || !info.DownLoadUrl.ToLower().StartsWith("https://"))
{
throw new Exception("非法的下载地址！");
}
downloadSize = 0;
await Task.Run(() =>
{
try
{
long totalSize = 0;
long threadInitedLength = 0; //分配线程任务的下载量
#region 获取文件信息
//打开网络连接
HttpWebRequest initRequest = (HttpWebRequest)WebRequest.Create(info.DownLoadUrl);
WebResponse initResponse = initRequest.GetResponse();
FileInfo fileMsg = FileInfo.GetFileMessage(initResponse);
totalSize = fileMsg.Length;
if ((!string.IsNullOrEmpty(fileMsg.FileName)) && info.LocalSaveFolder != null)
{
info.SavePath = Path.Combine(info.LocalSaveFolder, fileMsg.FileName);
}
//ReaderWriterLock readWriteLock = new ReaderWriterLock();
#endregion
#region 读取配置文件
string configPath = info.SavePath.Substring(0, info.SavePath.LastIndexOf(".")) + ".cfg";
FileDownloadConfig initInfo = null;
if (File.Exists(configPath) && (info.IsNew == false))
{
initInfo = FileDownloadConfig.ReadConfig(configPath);
downloadSize = (long)initInfo.DownloadSize;
totalSize = (long)initInfo.TotalSize;
}
#endregion
#region 计算速度
//Stopwatch MyStopWatch = new Stopwatch();
long lastDownloadSize = 0; //上次下载量
bool isSendCompleteEvent = false; //是否完成
Timer timer = new Timer(new TimerCallback((o) =>
{
if (!isSendCompleteEvent)
{
FileDownloadEvent e = new FileDownloadEvent();
e.DownloadSize = downloadSize;
e.TotalSize = totalSize;
if (totalSize > 0 && downloadSize == totalSize)
{
e.Speed = 0;
isSendCompleteEvent = true;
eventFinished.Set();
}
else
{
e.Speed = downloadSize - lastDownloadSize;
lastDownloadSize = downloadSize; //更新上次下载量
}
DownloadEvent(e);
}
}), null, 0, 1000);
#endregion
string tempPath = info.SavePath.Substring(0, info.SavePath.LastIndexOf(".")) + ".dat";
#region 多线程下载
//分配下载队列
Queue <ThreadDownloadInfo> downQueue = null;
if (initInfo == null || info.IsNew)
{
downQueue = new Queue <ThreadDownloadInfo>(); //下载信息队列
while (threadInitedLength < totalSize)
{
ThreadDownloadInfo downInfo = new ThreadDownloadInfo();
downInfo.StartLength = threadInitedLength;
downInfo.Length = (int)Math.Min(Math.Min(THREAD_BUFFER_SIZE, totalSize - threadInitedLength), totalSize / info.ThreadCount); //下载量
downQueue.Enqueue(downInfo);
threadInitedLength += downInfo.Length;
}
}
else
{
downQueue = initInfo.DownloadQueue;
}
FileStream fs = new FileStream(tempPath, FileMode.OpenOrCreate);
fs.SetLength(totalSize);
int threads = info.ThreadCount;
for (int i = 0; i < info.ThreadCount; i++)
{
ThreadPool.QueueUserWorkItem((state) =>
{
ThreadWork(info.DownLoadUrl, fs, downQueue);
if (Interlocked.Decrement(ref threads) == 0)
{
(state as AutoResetEvent).Set();
}
}, eventFinished);
}
//等待所有线程完成
eventFinished.WaitOne();
if (fs != null)
{
fs.Close();
}
fs = null;
if (File.Exists(info.SavePath))
{
File.Delete(info.SavePath);
}
if (downloadSize == totalSize)
{
File.Move(tempPath, info.SavePath);
File.Delete(configPath);
}
if (cancelTokenSource.IsCancellationRequested && StopEvent != null)
{
StopEvent();
//保存配置文件
FileDownloadConfig.SaveConfig(configPath, downloadSize, totalSize, downQueue);
}
#endregion
}
catch (Exception ex)
{
ErrorMakedEvent?.Invoke(ex.Message);
}
});
}