BackgroundWorker组件的作用

当构建一个图形化的Windows Form桌面应用程序并且需要执行在应用程序主UI线程之外的线程中长时间的任务时，BackgroundWorker类就很有用了。

要使用BackgroundWorker，我们只需要告诉它希望在后台执行那个方法并且调用RunWorkerAsync（）即可

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

        private void button1_Click(object sender, EventArgs e)
        {
            int a = int.Parse(textBox1.Text.Trim());
            int b = int.Parse(textBox2.Text.Trim());
            Add ad = new Add(a,b);
            backgroundWorker1.RunWorkerAsync(ad);
        }

        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
              Add args=(Add)e.Argument;
              for (int i = ; i < ; i++)
              {
                  Thread.Sleep();
                  backgroundWorker1.ReportProgress(i*);
              }

              e.Result = args.a + args.b;
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            label1.Text = e.Result.ToString();
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            progressBar1.Value = e.ProgressPercentage;
        }
    }
    public class Add
    {
        public int a;
        public int b;
        public Add(int a, int b)
        {
            this.a = a;
            this.b = b;
        }

    }