c# 代理异步 回调

        Class1.StuDele _dele = null;

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Class1 c1 = new Class1();

            AsyncCallback callBack = new AsyncCallback(UploadComplete);

            _dele += new Class1.StuDele(Do1);

            IAsyncResult iResult = _dele.BeginInvoke("hha", callBack, null);
        }

        private void UploadComplete(IAsyncResult results)
        {
            System.Diagnostics.Debug.WriteLine("12345");
            if (this.InvokeRequired)
            {
                AsyncCallback callback = new AsyncCallback(UploadComplete);
                this.BeginInvoke(callback, results);
                return;
            }
        }

        string Do1(string str)
        {
            MessageBox.Show(str + "_1");

            return "Haha Excuted Do1!";
        }