c# BackgroundWorker

    public partial class Form1 : Form
    {
 
        public Form1()
        {
            InitializeComponent();
        }
 
        private void btnStart_Click(object sender, EventArgs e)
        {
            if (bgWorker.IsBusy)              //判断是否正在运行异步操作
                return;
            this.progressBar1.Maximum = 100;  //设置进度条最大值
            this.btnStart.Enabled = false;
            this.btnStop.Enabled = true;
            bgWorker.RunWorkerAsync("11111");   //给业务传递参数，就是把前台的要处理的参数传递进去
        }
 
        public void bgWorker_DoWork(object sender, DoWorkEventArgs e)
        {
            //业务处理
            object s = e.Argument;   //这的e.Argument就是上面传递的参数 11111
            for (int i = 0; i <= this.progressBar1.Maximum; i++)
            {
                if (bgWorker.CancellationPending)     //此处关联的是btnStop_Click事件中的这个bgWorker.CancelAsync();如果这个触发了，那么就会停止。
                {
                    e.Cancel = true;
                    return;
                }
                else
                {
                    bgWorker.ReportProgress(i, "222222"); //向bgWorker_ProgessChanged事件传递参数，第一个是进度的参数，第二个是你要处理业务的参数
                    System.Threading.Thread.Sleep(1);
                }
            }
        }
 
        public void bgWorker_ProgessChanged(object sender, ProgressChangedEventArgs e)
        {
            //页面处理
            string state = (string)e.UserState;//接收上bgWorker.ReportProgress方法传递过来的参数userState
            this.progressBar1.Value = e.ProgressPercentage;
            this.label1.Text = "处理进度:" + Convert.ToString(e.ProgressPercentage) + "%";
            //label2.Text = e.ProgressPercentage.ToString();
        }
 
        public void bgWorker_WorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Error != null)
            {
                MessageBox.Show(e.Error.ToString());
                return;
            }
            if (!e.Cancelled)
                this.label1.Text = "处理完毕!";
            else
                this.label1.Text = "处理终止!";
 
        }
 
        private void btnStop_Click(object sender, EventArgs e)
        {
            this.btnStart.Enabled = true;
            this.btnStop.Enabled = false;
            bgWorker.CancelAsync();
        }
 
    }