1.程式實現了一個簡單的使用了BackgroundWorker類的WPF程式，用於在後臺執行緒給進度條賦值。

執行結果如下：

後臺執行緒正常執行結束：

後臺執行緒中途被取消：

2.程式僅修改了 MainWindow.xaml 檔案和 MainWindow.xaml.cs 檔案，兩個檔案內容如下

MainWindow.xaml 檔案：

<Window x:Class="SimpleWorker.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="150" Width="250">
    <StackPanel>
        <ProgressBar Name="progressBar" Height="20" Width="200" Margin="10"></ProgressBar>
        <Button Name="btnProcess" Width="100" Click="btnProcess_Click" Margin="5">開始後臺任務</Button>
        <Button Name="btnCancel" Width="100" Click="btnCancel_Click" Margin="5">取消後臺任務</Button>
    </StackPanel>
</Window>
 

using System.Windows;
using System.ComponentModel;
using System.Threading;

namespace SimpleWorker
{
    /// <summary>
    /// MainWindow.xaml 的互動邏輯
    /// </summary>
    public partial class MainWindow : Window
    {
        BackgroundWorker bgWorker = new BackgroundWorker();
        public MainWindow()
        {
            InitializeComponent();

            bgWorker.WorkerReportsProgress = true;
            bgWorker.WorkerSupportsCancellation = true;
            bgWorker.DoWork += DoWork_Handler;
            bgWorker.ProgressChanged += ProgressChanged_Handler;
            bgWorker.RunWorkerCompleted += RunWorkerCompleted_Handler;
        }

        private void btnProcess_Click(object sender,RoutedEventArgs e)
        {
            if (!bgWorker.IsBusy)
            {
                bgWorker.RunWorkerAsync();
            }
        }

        private void ProgressChanged_Handler(object sender, ProgressChangedEventArgs args)
        {
            progressBar.Value = args.ProgressPercentage;
        }

        private void DoWork_Handler(object sender,DoWorkEventArgs args)
        {
            BackgroundWorker worker = sender as BackgroundWorker;
            for (int i = 1; i <= 10; i++)
            {
                if (worker.CancellationPending)
                {
                    args.Cancel = true;
                    break;
                }
                else
                {
                    worker.ReportProgress(i*10);
                    Thread.Sleep(500);
                }
            }
        }

        private void RunWorkerCompleted_Handler(object sender,RunWorkerCompletedEventArgs args)
        {
            progressBar.Value = 0;
            if (args.Cancelled)
            {
                MessageBox.Show("後臺任務已經被取消。", "訊息");
            }
            else
            {
                MessageBox.Show("後臺任務正常結束。","訊息");
            }
        }
        private void btnCancel_Click(object sender,RoutedEventArgs e)
        {
            bgWorker.CancelAsync();
        }
    }
}