using System; using System.ComponentModel; using System.Windows.Forms; using System.Threading; namespace WindowsFormsApplication1 {
      publicpartialclass Form1 : Form     {
          public Form1()         {
              InitializeComponent();             worker =new BackgroundWorker();             worker.DoWork+=new DoWorkEventHandler(worker_DoWork);             worker.ProgressChanged+=new ProgressChangedEventHandler(worker_ProgressChanged);             worker.RunWorkerCompleted+=new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);             worker.WorkerReportsProgress =true;  //允许进度显示             worker.WorkerSupportsCancellation =true; //允许运行中取消         }         BackgroundWorker worker;         privatevoid Form1_Load(object sender, EventArgs e)         {
          }         privatevoid worker_DoWork(object sender, DoWorkEventArgs e)         {
              for (int i =0; i <300; i++)             {
                  Thread.Sleep(100);                 //每隔一段时间就向主线程报告进度，以便更新进度条。                 //多数情况下，你只需要发送一个整数去更新即可                 worker.ReportProgress(i/3);                 if (worker.CancellationPending)                 {
                      //如果任务被取消                     e.Cancel =true;                     worker.ReportProgress(0);                     return;                 }             }         }         privatevoid worker_ProgressChanged(object sender, ProgressChangedEventArgs e)         {
              pbarThis.Value = e.ProgressPercentage;             lblText.Text ="已经处理了 "+ pbarThis.Value.ToString() +"%";         }         privatevoid worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)         {
              if (e.Cancelled)             {
                  lblText.Text ="任务取消";             }             elseif (e.Error !=null)             {
                  lblText.Text ="发生错误";             }             else             {
                  lblText.Text ="任务完成";             }             btnStart.Enabled =true;             btnCancel.Enabled =false;         }         privatevoid btnStart_Click(object sender, EventArgs e)             {
              btnStart.Enabled =false;             btnCancel.Enabled =true;             //通知主线程开始进行数据处理             worker.RunWorkerAsync();         }         privatevoid btnCancel_Click(object sender, EventArgs e)         {
              if (worker.IsBusy)             {
                  worker.CancelAsync();             }         }     } }