主窗体中添加代码

public FrmMain()        {            InitializeComponent();            System.Threading.Thread thread = new System.Threading.Thread(Do_work);                thread.IsBackground = true;                thread.Start();        } private void Do_work()        {            while (true)            {                //将sleep和无限循环放在等待异步的外面                 System.Threading.Thread.Sleep(5000);                System.Windows.Forms.Application.DoEvents();                ThreadFuntion();            }        } private void ThreadFuntion()        {            if (this.label_State.InvokeRequired)            {                //1 通常方法：将代理绑定到方法                  FlushClient fc = new FlushClient(ThreadFuntion);                this.BeginInvoke(fc);//通过代理调用刷新方法              }            else            {                label_State.Text = "程序已经运行5秒钟了";            }        }