【发布时间】：2022-01-14 15:59:06
【问题描述】：
我正在使用 this（稍作修改）从文件共享中复制大文件，如果下载中断，可以继续复制。它在 BackroudWorker 中运行并报告进度。这工作正常，但我希望能够在每次将文件数据块写入磁盘时以最小的额外开销将当前的 MD5 哈希写入磁盘（当前总数，而不是每个块一次）。如果发现部分文件，我想从文件中读取 MD5 哈希，如果它与部分文件相同，则继续复制。当文件被完全复制后，文件中的 MD5 哈希值应该是完全复制文件的 MD5 哈希值。我想稍后用它来确定源文件和目标文件是相同的。感谢您的帮助！
这是我目前的复制方法：
public static bool CopyFile(List<CopyObjects> FileList, FSObjToCopy job, BackgroundWorker BW)
{
Stopwatch sw = new Stopwatch();
long RestartPosition = 0;
bool Retry = false;
int BYTES_TO_READ = (0x200000)
foreach (CopyObjects co in FileList)
{
FileInfo fi = co.file;
FileInfo fo = null;
if (fi.Directory.FullName.StartsWith($@"{Test_Updater_Core.ServerName}\{Test_Updater_Core.ServerTemplateRoot}"))
{
if (File.Exists(fi.FullName.Replace($@"{Test_Updater_Core.ServerName}\{Test_Updater_Core.ServerTemplateRoot}", $@"{ Test_Updater_Core.USBStore_Drive.driveInfo.Name.Replace("\\", "")}\{Test_Updater_Core.UsbTemplateRoot}")))
{
fi = new FileInfo(fi.FullName.Replace($@"{Test_Updater_Core.ServerName}\{Test_Updater_Core.ServerTemplateRoot}", $@"{Test_Updater_Core.USBStore_Drive.driveInfo.Name.Replace("\\", "")}\{Test_Updater_Core.UsbTemplateRoot}"));
co.destination = co.destination.Replace($@"{Test_Updater_Core.USBStore_Drive.driveInfo.Name.Replace("\\", "")}\{Test_Updater_Core.UsbTemplateRoot}", $@"{Test_Updater_Core.LocalInstallDrive}\{Test_Updater_Core.LocalTemplateRoot}");
fo = new FileInfo($"{fi.FullName.Replace($@"{Test_Updater_Core.USBStore_Drive.driveInfo.Name.Replace("\\", "")}\{Test_Updater_Core.UsbTemplateRoot}", $@"{Test_Updater_Core.LocalInstallDrive}\{Test_Updater_Core.LocalTemplateRoot}")}{Test_Updater_Core.TempFileExtension}");
}
}
//If a clean cancellation was requested, we do it here, otherwise the BackgroundWorker will be killed
if (BW.CancellationPending)
{
job.Status = FSObjToCopy._Status.Complete;
return false;
}
//If a pause is requested, we loop here until resume or termination has been signaled
while (job.PauseBackgroundWorker == true)
{
Thread.Sleep(100);
if (BW.CancellationPending)
{
job.Status = FSObjToCopy._Status.Complete;
return false;
}
Application.DoEvents();
}
if (fo == null)
fo = new FileInfo($"{fi.FullName.Replace(job.Source, co.destination)}{Test_Updater_Core.TempFileExtension}");
if (fo.Exists)
{
Retry = true;
RestartPosition = fo.Length - BYTES_TO_READ;
}
else
{
RestartPosition = 0;
Retry = false;
}
if (RestartPosition <= 0)
{
Retry = false;
}
sw.Start();
try
{
// Read source files into file streams
FileStream source = new FileStream(fi.FullName, FileMode.Open, FileAccess.Read);
// Additional way to write to file stream
FileStream dest = new FileStream(fo.FullName, FileMode.OpenOrCreate, FileAccess.Write);
// Actual read file length
int destLength = 0;
// If the length of each read is less than the length of the source file, read in chunks
if (BYTES_TO_READ < source.Length)
{
byte[] buffer = new byte[BYTES_TO_READ];
long copied = 0;
if (Retry)
{
source.Seek(RestartPosition, SeekOrigin.Begin);
dest.Seek(RestartPosition, SeekOrigin.Begin);
Retry = false;
}
while (copied <= source.Length - BYTES_TO_READ)
{
destLength = source.Read(buffer, 0, BYTES_TO_READ);
source.Flush();
dest.Write(buffer, 0, BYTES_TO_READ);
dest.Flush();
// Current position of flow
dest.Position = source.Position;
copied += BYTES_TO_READ;
job.CopiedSoFar += BYTES_TO_READ;
if (sw.ElapsedMilliseconds > 250)
{
job.PercComplete = (int)(float)((float)job.CopiedSoFar / (float)job.TotalFileSize * 100);
sw.Restart();
sw.Start();
job.ProgressCell.Value = job.PercComplete;
BW.ReportProgress(job.PercComplete < 100 ? job.PercComplete : 99);
}
if (BW.CancellationPending)
{
job.Status = FSObjToCopy._Status.Complete;
return false;
}
while (job.PauseBackgroundWorker == true)
{
Thread.Sleep(100);
if (BW.CancellationPending)
{
job.Status = FSObjToCopy._Status.Complete;
return false;
}
Application.DoEvents();
}
}
int left = (int)(source.Length - copied);
destLength = source.Read(buffer, 0, left);
source.Flush();
dest.Write(buffer, 0, left);
dest.Flush();
job.CopiedSoFar += left;
}
else
{
// If the file length of each copy is longer than that of the source file, the actual file length is copied directly.
byte[] buffer = new byte[source.Length];
source.Read(buffer, 0, buffer.Length);
source.Flush();
dest.Write(buffer, 0, buffer.Length);
dest.Flush();
job.CopiedSoFar += source.Length;
job.PercComplete = (int)(float)((float)job.CopiedSoFar / (float)job.TotalFileSize * 100);
job.ProgressCell.Value = job.PercComplete;
BW.ReportProgress(job.PercComplete < 100 ? job.PercComplete : 99);
}
source.Close();
dest.Close();
fo.LastWriteTimeUtc = fi.LastWriteTimeUtc;
if (File.Exists(fo.FullName))
{
if (File.Exists(fo.FullName.Replace($"{Test_Updater_Core.TempFileExtension}", "")))
{
File.Delete(fo.FullName.Replace($"{Test_Updater_Core.TempFileExtension}", ""));
}
File.Move(fo.FullName, fo.FullName.Replace($"{Test_Updater_Core.TempFileExtension}", ""));
}
job.ProgressCell.Value = job.PercComplete;
BW.ReportProgress(job.PercComplete);
}
catch (Exception ex)
{
MessageBox.Show($"There was an error copying:{Environment.NewLine}{fi}{Environment.NewLine}to:" +
$"{Environment.NewLine}{fo}{Environment.NewLine}The error is: {Environment.NewLine}{ex.Message}",
"Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
job.Status = FSObjToCopy._Status.Error;
return false;
}
finally
{
sw.Stop();
}
}
return true;
}
【问题讨论】：
-
有一行“md5InFile.TransformBlock(buffer,)”不应该存在。抱歉！
-
BackgoundWorker 类自 2012 年以来已过时，完全被 async/await、Task.Run 和 IProgress
取代。 MD5 类有一个 ComputeHashAsync(Stream,CancellationToken) 方法，这意味着所有这些代码都可以替换为 4-5 行 -
您还可以同时处理多个文件，这是 BGW 无法做到的
-
@Panagiotis Kanavos：太棒了！愿意分享吗？
-
我其实每批文件都有一个BGW。所以每次调用 CopyFile(List
FileList, FSObjToCopy job, BackgroundWorker BW) 实际上有多个相关文件（FileList），但是可以并行调用。
标签： c# md5 filestream file-copying