namespace BackgroundWorkderPauseSample{    public partial class MainForm : Form    {        BackgroundWorker worker = null;        public MainForm()        {            InitializeComponent();            Load += new EventHandler(Form1_Load);        }        void Form1_Load(object sender, EventArgs e)        {            worker = new BackgroundWorker();            worker.WorkerReportsProgress = true;            worker.WorkerSupportsCancellation = true;            worker.DoWork += new DoWorkEventHandler(worker_DoWork);            worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);            worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);                    }        void worker_ProgressChanged(object sender, ProgressChangedEventArgs e)        {            progressBar1.Value = e.ProgressPercentage;        }        void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)        {            if (e.Cancelled)                MessageBox.Show("用户取消了操作");            else            {                MessageBox.Show("正常完成了操作");            }        }        void worker_DoWork(object sender, DoWorkEventArgs e)        {            for (int i = 0; i < 100; i++)            {                if (worker.CancellationPending)//如果用户申请取消                {                    for (int k = i; k >= 0; k--)                    {                        Thread.Sleep(10);                        worker.ReportProgress(k);//模拟一个回滚的效果                    }                    e.Cancel = true;                    return;                }                manualReset.WaitOne();//如果ManualResetEvent的初始化为终止状态（true），那么该方法将一直工作，直到收到Reset信号。然后，直到收到Set信号，就继续工作。                //反之亦然                Thread.Sleep(500);                worker.ReportProgress(i+1);            }        }        private void btStart_Click(object sender, EventArgs e)        {            worker.RunWorkerAsync();        }        private void btCancel_Click(object sender, EventArgs e)        {            worker.CancelAsync();        }        private ManualResetEvent manualReset = new ManualResetEvent(true);        private void btPause_Click(object sender, EventArgs e)        {            if (btPause.Text == "暂停")            {                manualReset.Reset();//暂停当前线程的工作，发信号给waitOne方法，阻塞                btPause.Text = "继续";            }            else            {                manualReset.Set();//继续某个线程的工作                btPause.Text = "暂停";            }        }    }}