private BackgroundWorker bgWorker = new BackgroundWorker();
bgWorker.WorkerReportsProgress = true;

bgWorker.WorkerSupportsCancellation = true;

//在DoWork中鍵入如下代碼
for (int i = 0; i <= 100; i++)
{
    if (bgWorker.CancellationPending)
    {
        e.Cancel = true;
        return;
    }
    else
    {
        bgWorker.ReportProgress(i,"Working");
        System.Threading.Thread.Sleep(10);
    }
}

//防止重復(fù)執(zhí)行異步操作引發(fā)錯(cuò)誤
if (bgWorker.IsBusy)
    return;
bgWorker.RunWorkerAsync();

//在啟動(dòng)異步操作的地方鍵入代碼
bgWorker.RunWorkerAsync("hello");

for (int i = 0; i <= 100; i++)
{
    //向ProgressChanged報(bào)告進(jìn)度
    bgWorker.ReportProgress(i,"Working");
    System.Threading.Thread.Sleep(10);
}

//在需要執(zhí)行取消操作的地方鍵入以下代碼
bgWorker.CancelAsync();

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace PrograssBar
{
    public partial class PrograssBarUseBackgroundWorker : Form
    {

        private BackgroundWorker bgWorker = new BackgroundWorker();

        public PrograssBarUseBackgroundWorker()
        {
            InitializeComponent();
            InitializeBackgroundWorker();
        }

        private void InitializeBackgroundWorker()
        {
            bgWorker.WorkerReportsProgress = true;
            bgWorker.WorkerSupportsCancellation = true;
            bgWorker.DoWork += new DoWorkEventHandler(bgWorker_DoWork);
            bgWorker.ProgressChanged += new ProgressChangedEventHandler(bgWorker_ProgessChanged);
            bgWorker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(bgWorker_WorkerCompleted);
        }

        private void btnStart_Click(object sender, EventArgs e)
        {
            if (bgWorker.IsBusy)
                return;
            this.progressBar1.Maximum = 100;
            this.btnStart.Enabled = false;
            this.btnStop.Enabled = true;
            bgWorker.RunWorkerAsync("hello");
        }

        public void bgWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            for (int i = 0; i <= 100; i++)
            {
                if (bgWorker.CancellationPending)
                {
                    e.Cancel = true;
                    return;
                }
                else
                {
                    bgWorker.ReportProgress(i,"Working");
                    System.Threading.Thread.Sleep(10);
                }
            }
        }

        public void bgWorker_ProgessChanged(object sender, ProgressChangedEventArgs e)
        {
            //string state = (string)e.UserState;//接收ReportProgress方法傳遞過(guò)來(lái)的userState
            this.progressBar1.Value = e.ProgressPercentage;
            this.label1.Text = "處理進(jìn)度:" + Convert.ToString(e.ProgressPercentage) + "%";
        }

        public void bgWorker_WorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if(e.Error!=null)
            {
                MessageBox.Show(e.Error.ToString());
                return;
            }
            if (!e.Cancelled)
                this.label1.Text = "處理完畢!";
            else
                this.label1.Text = "處理終止!";

        }

        private void btnStop_Click(object sender, EventArgs e)
        {
            this.btnStart.Enabled = true;
            this.btnStop.Enabled = false;
            bgWorker.CancelAsync();
        }
    }
}