控制台中的處理標准輸出與重定向時不同

Question

在Windows C＃應用程序中，我們要運行cipher.exe來從未使用的磁盤空間（在本例中為D：驅動器）中刪除數據：

cipher.exe /w:D:\

從Windows命令行完成后，輸出為：

To remove as much data as possible, please close all other applications while
running CIPHER /W.
Writing 0x00
...................................................................................................
Writing 0xFF
...................................................................................................
Writing Random Numbers
...................................................................................................

這些帶有點的線在加密過程的持續時間內逐漸填充。 我們認為應該從C＃應用程序中讀取這些點以跟蹤進度並將其顯示在進度條上。 但是，我們注意到，當捕獲或重定向標准輸出時，順序是不同的：

cipher.exe /w:D:\ > out.txt

結果文件包含以下內容：

To remove as much data as possible, please close all other applications while
running CIPHER /W.
Writing 0x00
Writing 0xFF
Writing Random Numbers
...................................................................................................
...................................................................................................
...................................................................................................

因此，當我們嘗試從C＃應用程序中捕獲這些內容時，直到過程結束時才讀取點。 例如，當使用以下代碼時：

private void RunCipher()
{
    using (Process cipherProcess = new Process())
    {
        try
        {
            // Cipher does three phases, one with 00s, one with FFs and one with random bits
            // We count dots in the output for each phase to track the progress
            // The amount of dots per phase is always 99 (independent of the volume size)
            // See the end of this file to find the expected output

            cipherProcess.StartInfo.FileName = "cipher.exe";
            cipherProcess.StartInfo.Arguments = @"/w:D:\";

            cipherProcess.StartInfo.RedirectStandardOutput = true;
            cipherProcess.StartInfo.RedirectStandardError = true;
            cipherProcess.StartInfo.RedirectStandardInput = true;
            cipherProcess.StartInfo.UseShellExecute = false;
            cipherProcess.StartInfo.CreateNoWindow = true;

            cipherProcess.OutputDataReceived += CipherProcess_OutputDataReceived;
            cipherProcess.ErrorDataReceived += CipherProcess_ErrorDataReceived;
            cipherProcess.Exited += CipherProcess_Exited;

            cipherProcess.Start();

            cipherProcess.BeginOutputReadLine();
            cipherProcess.BeginErrorReadLine();
            cipherProcess.WaitForExit();
        }
        catch
        {
            Console.WriteLine("Exception occured");
        }
    }
    Console.WriteLine("Fininshed");
}

private void CipherProcess_OutputDataReceived(object sender, DataReceivedEventArgs e)
{
    Console.WriteLine("OutputDataReceived: " + e.Data);
}

private void CipherProcess_Exited(object sender, EventArgs e)
{
    Console.WriteLine("Exited");
}

private void CipherProcess_ErrorDataReceived(object sender, DataReceivedEventArgs e)
{
    Console.WriteLine("ErrorDataReceived: " + e.Data);
}

輸出為：

OutputDataReceived: To remove as much data as possible, please close all other applications while
OutputDataReceived: running CIPHER /W.
OutputDataReceived: Writing 0x00
The thread 0x41ac has exited with code 0 (0x0).
The thread 0x408c has exited with code 0 (0x0).
OutputDataReceived: Writing 0xFF
The thread 0x39e4 has exited with code 0 (0x0).
The thread 0x3e30 has exited with code 0 (0x0).
OutputDataReceived: Writing Random Numbers
The thread 0x34ac has exited with code 0 (0x0).
The thread 0x3960 has exited with code 0 (0x0).
OutputDataReceived: ...................................................................................................
OutputDataReceived: ...................................................................................................
OutputDataReceived: ...................................................................................................
ErrorDataReceived: 
OutputDataReceived: 
Fininshed

我們還嘗試了不使用OutputDataReceived + BeginOutputReadLine而是使用process.StandardOutput.Read（）的方法，但是它具有相同的問題：它首先讀取所有三個“ Writing（..）”輸出：

private void RunCipher2()
{
    using (Process cipherProcess = new Process())
    {
        try
        {
            cipherProcess.StartInfo.FileName = "cipher.exe";
            cipherProcess.StartInfo.Arguments = @"/w:D:\";

            cipherProcess.StartInfo.RedirectStandardOutput = true;
            cipherProcess.StartInfo.RedirectStandardError = true;
            cipherProcess.StartInfo.RedirectStandardInput = true;
            cipherProcess.StartInfo.UseShellExecute = false;
            cipherProcess.StartInfo.CreateNoWindow = true;

            cipherProcess.Start();

            while (!cipherProcess.StandardOutput.EndOfStream)
            {
                char nextChar = (char)cipherProcess.StandardOutput.Read();
                Console.Write(nextChar);
            }

            cipherProcess.WaitForExit();
        }
        catch
        {
            Console.WriteLine("Exception occured");
        }
    }
    Console.WriteLine("Fininshed");
}

而且輸出仍然是我們無法期望的：

To remove as much data as possible, please close all other applications while
running CIPHER /W.
Writing 0x00
Writing 0xFF
Writing Random Numbers
...................................................................................................
...................................................................................................
...................................................................................................
Fininshed

我們已經找到了該線程，但是該解決方案需要將重定向的輸出進行首次工作： 在收到新行之前讀取Process StandardOutput

這里發生了什么事？ 有沒有辦法使這項工作？ 還是以其他方式跟蹤進度？ 當然，我們可以檢測到“ Writing”消息，並以三分之二的速度報告進度……但是看來這應該是可能的:)

Answer 1

假設隨着進展的進行，“ ...”以遞增方式出現，那么您需要執行的操作是捕獲StandardOutput流並一次讀取一個字符，而不是使用DataRecieved事件。 這樣，您將看到每個句號被寫出來。 然后，您可以計算自己擁有的數量，並以此來推斷進度。