处理文件时更新进度条

Question

我目前正在从事一个有趣的项目。这是一个 C# WinForms 项目。基本上，使用应该加载一个Visual Studio解决方案文件，然后应用程序对其进行解析：根据文件中写入的内容构建对象等等（详细解释它的作用与问题无关，所以我会停在这里）。

我有一个主窗体 (frmMain)，它提供了加载文件的界面，还有一个进度条 (analyzingProgressBar)，应该显示文件解析的进度，因为它需要几秒钟。我已经设置了BackgroundWorker，但是卡住了-如何根据实际进度更新prgressbar？

我的代码是：

public partial class frmMain : Form
{
    public frmMain()
    {
        InitializeComponent();
        toolStripPseudo.Text = String.Empty;
        toolStripPseudo.Spring = true;
    }

    private void openSolutionToolStripMenuItem_Click(object sender, EventArgs e)
    {
        if (openSolutionDialog.ShowDialog() == DialogResult.OK)
        {
            Solution openSolution = new Solution(openSolutionDialog.FileName);

            BackgroundWorker worker = new BackgroundWorker();
            worker.WorkerReportsProgress = true;
            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(this.RunWorkerCompleted);
            worker.ProgressChanged += new ProgressChangedEventHandler(this.ProgressChanged);
            worker.DoWork += new DoWorkEventHandler(this.DoWork);

            // start the worker thread
            worker.RunWorkerAsync(openSolution);
        }
    }

    private void DoWork(object sender, DoWorkEventArgs e)
    {
        // get a reference to the worker that started this request
        BackgroundWorker workerSender = sender as BackgroundWorker;

        Solution openSolution = e.Argument as Solution;
        openSolution.AnalyzeSolution();

        workerSender.ReportProgress() //What do I do here?
    }

    private void RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        // TODO add graphics
    }

    public void ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        analyzingProgressBar.Value = e.ProgressPercentage;
    }
}

Answer 1

通常，要显示进度如何变化，您需要在 DoWork 事件中进行某种循环，然后将百分比和/或消息返回给 UI 线程：

private void DoWork(object sender, DoWorkEventArgs e)
{
    var workerSender = (BackgroundWorker)sender;

    // I know I'm making this up.. I have no idea what your method does/returns
    var filesToAnalyze = ((Solution)e.Argument).AnalyzeSolution();

    for (var i = 0; i < filesToAnalyze.Length; i++)
        workerSender.ReportProgress(0, "Analyzing file #" + i);
}

由于您没有要迭代的内容，而只想在单独的后台线程中调用您的单个方法，因此不必费心报告进度。除非您以某种方式分解单个方法调用，否则您无能为力。

添加ProgressBar，将Style 设置为“Marquee”；在启动线程之前显示它并在RunWorkerCompleted事件中隐藏它：

progressBar.Show();
worker.RunWorkerAsync(openSolution);
...

private void DoWork(object sender, DoWorkEventArgs e)
{
    var openSolution = (Solution)e.Argument;

    // Run long method (which can't touch the UI, or it'll throw an exception)
    openSolution.AnalyzeSolution();
}

private void RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    progressBar.Hide();  // Hide progress bar when job complete
}

---

AnalyzeSolution() 只是连续调用一些（比如说，5 个）其他方法。我可以在每个方法完成时将进度条加 20% 之类的吗？

是的，但是您必须调用这 5 个方法，而不仅仅是调用 AnalyzeSolution()：

private void DoWork(object sender, DoWorkEventArgs e)
{
    var workerSender = (BackgroundWorker)sender;
    var openSolution = (Solution)e.Argument;

    openSolution.RunMethodOne();
    workerSender.ReportProgress(20);

    openSolution.RunMethodTwo();
    workerSender.ReportProgress(40);

    ...
}