c# - 设置文件压缩属性

Question

我期望这段代码:

if (!File.Exists(fullFileName))
{
    File.Create(fullFileName);
}

File.SetAttributes(fullFileName, FileAttributes.Compressed);

要设置这个标志:

但它没有...我做错了什么？如何在文件上设置该标志？

---

更新:它说 in the documentation

"It is not possible to change the compression status of a File object using the SetAttributes method."

而且显然它在使用静态 File.SetAttributes 时也不起作用。

鉴于此，如何实现这一点？

Answer 1

您可以使用 p/invoke 来压缩文件。

我给自己做了一个静态辅助函数:

public static class FileTools
{
  private const int FSCTL_SET_COMPRESSION = 0x9C040;
  private const short COMPRESSION_FORMAT_DEFAULT = 1;

  [DllImport("kernel32.dll", SetLastError = true)]
  private static extern int DeviceIoControl(
      IntPtr hDevice,
      int dwIoControlCode,
      ref short lpInBuffer,
      int nInBufferSize,
      IntPtr lpOutBuffer,
      int nOutBufferSize,
      ref int lpBytesReturned,
      IntPtr lpOverlapped);

  public static bool EnableCompression(IntPtr handle)
  {
    int lpBytesReturned = 0;
    short lpInBuffer = COMPRESSION_FORMAT_DEFAULT;

    return DeviceIoControl(handle, FSCTL_SET_COMPRESSION,
        ref lpInBuffer, sizeof(short), IntPtr.Zero, 0,
        ref lpBytesReturned, IntPtr.Zero) != 0;
  }
}

例如，我在代码中使用文件名:

using (var fileToCompress = File.Open(fileNameToCompress, FileMode.Open, FileAccess.ReadWrite, FileShare.None))
  FileTools.EnableCompression(fileToCompress.Handle);