Question

在执行某些任务时，不会更新BackgroundWorker的进度条。我想要访问的是进度条在遍历DirectoryInfo中的每个文件时移动。假设我们有20个文件＆＃34; .sql＆＃34;第一个文件完成时应该是5％，10％等。这是我的代码。

private void CSV_Click(object sender, RoutedEventArgs e)
        {         
            try
            {
                btnExtract.IsEnabled = false;
                workerextract.RunWorkerAsync();

        }
        catch (Exception ex)
        {
            System.Windows.MessageBox.Show(ex.Message);
        }
    }

    private void workerextract_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
    {
        try
        {
           this.Dispatcher.Invoke(() =>
            {

                DirectoryInfo di = new DirectoryInfo(txtQueryfolder.Text);
                files = di.GetFiles("*.sql").Count();
                currentfile = 0;

                foreach (FileInfo fi in di.GetFiles("*.sql"))
                {
                    // Open the text file using a stream reader.
                    using (StreamReader sr = new StreamReader(fi.FullName))
                    {
                        // Read the stream to a string, and write the string to the console.
                        string line = sr.ReadToEnd();

                        //System.Windows.MessageBox.Show(line);
                        ExtractToCSV(line, System.IO.Path.GetFileNameWithoutExtension(fi.Name));
                        currentfile++;
                    }
                    int percentage = (currentfile + 1) * 100 / files;
                    workerextract.ReportProgress(percentage);
                }

            });

        }
        catch(Exception ex)
        {
            System.Windows.MessageBox.Show(ex.Message);
        }
    }

    private void workerextract_ProgressChanged(object sender, System.ComponentModel.ProgressChangedEventArgs e)
    {
        progressBarExtract.Value = e.ProgressPercentage;
    }

    private void workerextract_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        btnExtract.IsEnabled = true;
        System.Windows.MessageBox.Show("CSV Data extraction finished!");
    }

我找到了

private void workerextract_ProgressChanged（object sender， System.ComponentModel.ProgressChangedEventArgs e）

100％时，

在结束时被调用一次。另外，

private void workerextract_RunWorkerCompleted（object sender， RunWorkerCompletedEventArgs e）

从未打电话，因为我最后没有看到消息框。

所以，我觉得我在这里做错了，你能指导我吗？

Answer 1

在this.Dispatcher.Invoke的{{1}}事件中使用BackgroundWorker，您正在UI线程中执行整个操作;这是DoWork生来就是为了避免这样做。

此外，由于您正在访问一个BackgroundWorker的UI对象，因此从调度程序中解包您的代码会出错。

只需使用：

txtQueryfolder

当您调用private void workerextract_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e) { string queryFolder = e.Argument.ToString(); try { DirectoryInfo di = new DirectoryInfo(queryFolder); files = di.GetFiles("*.sql").Count(); currentfile = 0; foreach (FileInfo fi in di.GetFiles("*.sql")) { // Open the text file using a stream reader. using (StreamReader sr = new StreamReader(fi.FullName)) { // Read the stream to a string, and write the string to the console. string line = sr.ReadToEnd(); //System.Windows.MessageBox.Show(line); // ExtractToCSV shouldn't access to a UI object. ExtractToCSV(line, System.IO.Path.GetFileNameWithoutExtension(fi.Name)); currentfile++; } int percentage = (currentfile + 1) * 100 / files; workerextract.ReportProgress(percentage); } } catch (Exception ex) { // Don't use MessageBox in a thread different from the UI one. Just set the result (e.Result) and get that in the RunWorkerCompleted event. // System.Windows.MessageBox.Show(ex.Message); } }方法时，只需添加如下参数：

RunWorkerAsync

Answer 2

问题在于将整个DoWork包装在Dispatcher.Invoke中。我需要只包含那些与UI交互的代码。所以我适当地改变了代码并且它有效。

 private void workerextract_DoWork(object sender, System.ComponentModel.DoWorkEventArgs e)
        {
            try
            {
                this.Dispatcher.Invoke(() =>
                {
                    di = new DirectoryInfo(txtQueryfolder.Text);
                });
                    files = di.GetFiles("*.sql").Count();
                    currentfile = 0;

                foreach (FileInfo fi in di.GetFiles("*.sql"))
                {
                    // Open the text file using a stream reader.
                    using (StreamReader sr = new StreamReader(fi.FullName))
                    {
                        // Read the stream to a string, and write the string to the console.
                        string line = sr.ReadToEnd();

                        this.Dispatcher.Invoke(() =>
                        {
                        //System.Windows.MessageBox.Show(line);
                        ExtractToCSV(line, System.IO.Path.GetFileNameWithoutExtension(fi.Name));
                        });

                        currentfile++;
                    }
                    int percentage = (currentfile + 1) * 100 / files;
                    workerextract.ReportProgress(percentage);
                }
        }
        catch(Exception ex)
        {
            System.Windows.MessageBox.Show(ex.Message);
        }
    }

感谢所有人展示方向。

BackgroundWorker的进度条不起作用

2 个答案: