private BackgroundWorker _demoBGWorker = new BackgroundWorker();
_demoBGWorker.DoWork += BGWorker_DoWork;
_demoBGWorker.RunWorkerAsync();
private void BGWorker_DoWork(object sender, DoWorkEventArgs e)
{
  //在這里執(zhí)行耗時(shí)的運(yùn)算。
  int sum = 0;
  for (int i = 0; i <= 100; i++)
  {
    sum += i;
  }
}

//別忘了設(shè)置滾動(dòng)條。
this.progressBarSum.Maximum = 100;
_demoBGWorker.RunWorkerAsync(100);
//下面是更新后的 BGWorker_DoWork 方法：
private void BGWorker_DoWork(object sender, DoWorkEventArgs e)
{
  //在這里執(zhí)行耗時(shí)的運(yùn)算。
  int endNumber = 0;
  if(e.Argument != null)
  {
    endNumber = (int)e.Argument;
  }
  int sum = 0;
  for (int i = 0; i <= endNumber; i++)
  {
    sum += i;
  }
}

_demoBGWorker.WorkerReportsProgress = true;
_demoBGWorker.ProgressChanged += BGWorker_ProgressChanged;

private void BGWorker_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
  //修改進(jìn)度條的顯示。
  this.progressBarSum.Value = e.ProgressPercentage;

  //如果有更多的信息需要傳遞，可以使用 e.UserState 傳遞一個(gè)自定義的類型。
  //這是一個(gè) object 類型的對(duì)象，您可以通過(guò)它傳遞任何類型。
  //我們僅把當(dāng)前 sum 的值通過(guò) e.UserState 傳回，并通過(guò)顯示在窗口上。
  string message = e.UserState.ToString();
  this.labelSum.Text = message;
}

private void BGWorker_DoWork(object sender, DoWorkEventArgs e)
{
  BackgroundWorker bgWorker = sender as BackgroundWorker;
  int endNumber = 0;
  if(e.Argument != null)
  {
    endNumber = (int)e.Argument;
  }

  int sum = 0;
  for (int i = 0; i <= endNumber; i++)
  {
    sum += i;
    
    string message = "Current sum is: " + sum.ToString();
    //ReportProgress 方法把信息傳遞給 ProcessChanged 事件處理函數(shù)。
    //第一個(gè)參數(shù)類型為 int，表示執(zhí)行進(jìn)度。
    //如果有更多的信息需要傳遞，可以使用 ReportProgress 的第二個(gè)參數(shù)。
    //這里我們給第二個(gè)參數(shù)傳進(jìn)去一條消息。
    bgWorker.ReportProgress(i, message);
    Thread.Sleep(600);
  }
}

_demoBGWorker.WorkerSupportsCancellation = true;

 bgWorker.ReportProgress(i, message);
Thread.Sleep(600);

//在操作的過(guò)程中需要檢查用戶是否取消了當(dāng)前的操作。
if (bgWorker.CancellationPending == true)
{
  e.Cancel = true;
  break;
}

_demoBGWorker.CancelAsync();

_demoBGWorker.RunWorkerCompleted += BGWorker_RunWorkerCompleted;
private void BGWorker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
  //如果用戶取消了當(dāng)前操作就關(guān)閉窗口。
  if (e.Cancelled)
  {
    this.Close();
  }

  //計(jì)算已經(jīng)結(jié)束，需要禁用取消按鈕。
  this.btnCancel.Enabled = false;

  //計(jì)算過(guò)程中的異常會(huì)被抓住，在這里可以進(jìn)行處理。
  if (e.Error != null)
  {
    Type errorType = e.Error.GetType();
    switch (errorType.Name)
    {
      case "ArgumentNullException":
      case "MyException":
        //do something.
        break;
      default:
        //do something.
        break;
    }
  }

  //計(jì)算結(jié)果信息：e.Result
  //use it do something.
}

e.Result = sum;