避免线程切换时的BeginInvoke之舞

何谓BeginInvoke之舞.

delegate void MyHandlerDelegate();       
void MyHandler()
{
    // "The BeginInvoke dance"
    if (this.InvokeRequired){
        BeginInvoke( new MyHandlerDelegate(MyHandler) );
        return;
    }
       do GUI stuff
}

在做多线程的程序时,我们常常在经过大量计算后,要将结果反馈给UI.如果在多线程时,直接给UI的更新的话,会引发异常.相信大家都遇上过这样的问题,同时解决的方案就是上面的所谓BeginInvoke之舞.

 

在2.0里提供了AsyncOperationManager.支持异步方法调用的类提供并发管理.利用他就可以避免BeginInvoke了.再说每次写那样个东东也很烦.

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

        private void button1_Click(object sender, EventArgs e)
        {
            asyncOperation = AsyncOperationManager.CreateOperation(null);
            Thread t = new Thread(new ThreadStart(RunTask));
            t.Start();
        }

        public void RunTask()
        {
            Thread.Sleep(5000);
            asyncOperation.Post(new SendOrPostCallback(ShowText), "hello");
        }

        void ShowText(object s)
        {
            this.textBox1.Text = s.ToString();
        }
    }