如何从 FileStream 报告进度

Question

我想报告加密文件的进度，这是我的代码，我该怎么做？using (FileStream destination = new FileStream(destinationFilename, FileMode.CreateNew, FileAccess.Write, FileShare.None))using (CryptoStream cryptoStream = new CryptoStream(destination, transform, CryptoStreamMode.Write))using (FileStream source = new FileStream(sourceFilename, FileMode.Open, FileAccess.Read, FileShare.Read)){    await source.CopyToAsync(cryptoStream);}

Answer 1

要正确执行此操作，您需要插入另一个流来报告进度。所以像这样的事情...

        using (FileStream destination = new FileStream(destinationFilename, FileMode.CreateNew, FileAccess.Write, FileShare.None))

        using (CryptoStream cryptoStream = new CryptoStream(destination, transform, CryptoStreamMode.Write))

        using (FileStream source = new FileStream(sourceFilename, FileMode.Open, FileAccess.Read, FileShare.Read))

        {

            using (ProgressStream progressStream = new ProgressStream(source))

            {

                progressStream.UpdateProgress += ProgressStream_UpdateProgress;

                progressStream.CopyTo(cryptoStream);

            }

        }

ProgressStream 在哪里...

public class ProgressStream : Stream

{

    private Stream m_input = null;

    private long m_length = 0L;

    private long m_position = 0L;

    public event EventHandler<ProgressEventArgs> UpdateProgress;

    public ProgressStream(Stream input)

    {

        m_input = input;

        m_length = input.Length;

    }

    public override void Flush()

    {

        throw new System.NotImplementedException();

    }

    public override long Seek(long offset, SeekOrigin origin)

    {

        throw new System.NotImplementedException();

    }

    public override void SetLength(long value)

    {

        throw new System.NotImplementedException();

    }

    public override int Read(byte[] buffer, int offset, int count)

    {

        int n = m_input.Read(buffer, offset, count);

        m_position += n;

        UpdateProgress?.Invoke(this, new ProgressEventArgs((1.0f * m_position)/m_length));

        return n;

    }

    public override void Write(byte[] buffer, int offset, int count)

    {

        throw new System.NotImplementedException();

    }

    public override bool CanRead => true;

    public override bool CanSeek => false;

    public override bool CanWrite => false;

    public override long Length => m_length;

    public override long Position

    {

        get {  return m_position; }

        set {  throw new System.NotImplementedException();}

    }

}

ProgressEventArgs 是

public class ProgressEventArgs : EventArgs

{

    private float m_progress;

    public ProgressEventArgs(float progress)

    {

        m_progress = progress;

    }

    public float Progress => m_progress;

}

事件处理程序可能是这样的......

    private void ProgressStream_UpdateProgress(object sender, ProgressEventArgs e)

    {

        Console.WriteLine($"Progress is {e.Progress * 100.0f}%");

    }

当针对示例文件运行时会产生......

Progress is 5.272501%

Progress is 10.545%

Progress is 15.8175%

Progress is 21.09%

Progress is 26.3625%

Progress is 31.635%

Progress is 36.9075%

Progress is 42.18%

Progress is 47.4525%

Progress is 52.72501%

Progress is 57.99751%

Progress is 63.27001%

Progress is 68.5425%

Progress is 73.815%

Progress is 79.08751%

Progress is 84.36001%

Progress is 89.63251%

Progress is 94.90501%

Progress is 100%

Progress is 100%

有很大的增强和优化空间，但这是做你想做的事情的唯一有效方法。