C多线程的进度条

　　using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Linq; using System.Text; using System.Threading.Tasks; using System.Windows.Forms; using System.Threading;  namespace WindowsFormsApp4 {     public partial class Form1 : Form     {         public Form1()         {             InitializeComponent();         }          private async void button1_Click(object sender, EventArgs e)         {             var progressHandler = new Progress(value =>             {                 label2.Text = ＂当前值：＂ + value;                 progressBar1.Value = Convert.ToInt32(value);             });             var progress = progressHandler as IProgress;             await Task.Run(() =>             {                 for (int i = 0; i != 100; ++i)                 {                     if (progress != null)                         progress.Report(i.ToString());                     Thread.Sleep(100);                 }             });             label2.Text = ＂Completed.＂;         }     } }