多进程处理之BackgroundWorker

 

说明：通过本例对BackgroundWorker的WorkerReportsProgress,WorkerSupportsCancdllation属性及Dowork,ProessChanged,RunWorkerCompleted事件做进一步的了解。

 

  public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            //获取或设置一个值，该值指示BW报告能否报告进度更新
            backgroundWorker1.WorkerReportsProgress = true;
            //获取或设置一个值，该值指示BW是否支持异步取消
            backgroundWorker1.WorkerSupportsCancellation = true;
            buttonStop.Enabled = false;
        }

        private void buttonStart_Click(object sender, EventArgs e)
        {
            richTextBox1.Text = "开始产生10000以内的随机数……\n\n";
            buttonStart.Enabled = false;
            buttonStop.Enabled = true;
            //在后台开始操作
            backgroundWorker1.RunWorkerAsync();
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            //不要直接使用组件实例名称（backgroundWorker1），因为有多
            //个BackgroundWorker时，直接使用会产生耦合问题
            //应该通过下面的转换使用它
            BackgroundWorker worker = sender as BackgroundWorker;
            //下面的内容相当于线程要处理的内容。注意：不要在此事件中和控件打交道
            Random r = new Random();
            int numCount = 0;
            while (worker.CancellationPending == false)
            {
                int num = r.Next(10000);
                if (num % 5 == 0)
                {
                    numCount++;
                    //引发BW.ProgressChanged()事件
                    worker.ReportProgress(0, num);
                    Thread.Sleep(1000);
                }
            }
            //DoworkEventArgs.Result 获取或设置表示异步操作结果的值
            e.Result = numCount;
        }


        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            //object ProgressChangedEventArgs.UserState 获取唯一的用户状态
            int num = (int)e.UserState;
            richTextBox1.Text += num + ",";
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            if (e.Error == null)
            {
                richTextBox1.Text += "\n\n操作停止，共产生"+e.Result+"个能被5整除的随机数";
            }
            else
            {
                richTextBox1.Text += "\n操作过程中产生错误：" + e.Error;
            }
           
        }

        private void buttonStop_Click(object sender, EventArgs e)
        {
            //请求取消挂起后的操作
            backgroundWorker1.CancelAsync();
            buttonStop.Enabled = false;
            buttonStart.Enabled = true;
        }
    }