C#设计一个复制文件的进度条

以下是使用C#编写的复制文件的进度条示例代码：

using System;
using System.IO;
using System.Windows.Forms;

public class FileCopyProgressBar : Form
{
    private ProgressBar progressBar;
    private Button startButton;

    public FileCopyProgressBar()
    {
        Text = "File Copy Progress Bar";

        progressBar = new ProgressBar();
        progressBar.Dock = DockStyle.Top;
        Controls.Add(progressBar);

        startButton = new Button();
        startButton.Text = "Copy File";
        startButton.Dock = DockStyle.Bottom;
        startButton.Click += new EventHandler(OnStartButtonClicked);
        Controls.Add(startButton);
    }

    private void OnStartButtonClicked(object sender, EventArgs e)
    {
        string sourceFilePath = "path_to_source_file";
        string destinationFilePath = "path_to_destination_file";

        // Open the source file for reading
        using (FileStream sourceStream = new FileStream(sourceFilePath, FileMode.Open))
        {
            // Create the destination file
            using (FileStream destinationStream = new FileStream(destinationFilePath, FileMode.Create))
            {
                // Set the buffer size to 10KB
                byte[] buffer = new byte[10240];
                int bytesRead;

                long totalBytesRead = 0;
                long fileSize = sourceStream.Length;

                // Copy the file and update the progress bar
                while ((bytesRead = sourceStream.Read(buffer, 0, buffer.Length)) > 0)
                {
                    destinationStream.Write(buffer, 0, bytesRead);
                    totalBytesRead += bytesRead;

                    int percentComplete = (int)((double)totalBytesRead / fileSize * 100);
                    progressBar.Value = percentComplete;
                    Application.DoEvents();
                }
            }
        }

        MessageBox.Show("File copied successfully!");
    }

    public static void Main()
    {
        Application.Run(new FileCopyProgressBar());
    }
}

在上面的示例代码中，我们创建了一个名为`FileCopyProgressBar`的窗体，其中包含一个`ProgressBar`和一个`Button`。当用户单击`Button`时，我们将复制源文件到目标文件，并在进程中更新进度条。请注意，我们使用`Application.DoEvents()`来允许UI更新。