BackgroundWorker类 取消任务

//定义
BackgroundWorker  Bworker = new BackgroundWorker();                 
//Bworker.WorkerReportsProgress = true;
Bworker.DoWork += new DoWorkEventHandler(worker_DoWork);
//Bworker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);
Bworker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);

Bworker.WorkerSupportsCancellation = true;  //在执行过程中允许用户取消当前的操作

Bworker.RunWorkerAsync();

private void trigger(){
    //在触发事件中取消
    Bworker.CancelAsync();
}

private void worker_DoWork(object sender, DoWorkEventArgs e)
{
    for(;;){
        //在操作的过程中需要检查用户是否取消了当前的操作。
        if (bgWorker.CancellationPending == true)
        {
            e.Cancel = true;
            break;
        }

    }
}