WPF 异步

 1    public partial class Window1 : Window
 2    {
 3        /**//// <summary>
 4        /// 异步调用的委托
 5        /// </summary>
 6        /// <param name="name"></param>
 7        /// <returns></returns>
 8        public delegate string AsyncEventHandler(string name);
 9        /**//// <summary>
10        /// 异步完成更新界面的委托
11        /// </summary>
12        /// <param name="value"></param>
13        public delegate void UpdateUI(string value);
14
15        public Window1()
16        {
17            InitializeComponent();
18            this.btn1.Click += new RoutedEventHandler(btn1_Click);
19        }
20
21        void btn1_Click(object sender, RoutedEventArgs e)
22        {
23            //实例化委托
24            AsyncEventHandler async = new AsyncEventHandler(GetValue);
25            //开始异步
26            IAsyncResult ia = async.BeginInvoke("Hello World!", new AsyncCallback(CallBack), async);
27        }
28
29        /**//// <summary>
30        /// 异步完成CallBack方法
31        /// </summary>
32        /// <param name="result"></param>
33        private void CallBack(IAsyncResult result)
34        {
35            //转换返回值为委托类型
36            AsyncEventHandler async = (AsyncEventHandler)result.AsyncState;
37            //获得异步委托的返回值
38            string value = async.EndInvoke(result);
39            //实例化更新界面的委托
40            UpdateUI method = new UpdateUI(Update);
41            //开始界面委托
42            this.Dispatcher.Invoke(method, value);
43        }
44
45
46        /**//// <summary>
47        /// 更新界面
48        /// </summary>
49        /// <param name="value"></param>
50        private void Update(string value)
51        {
52            this.lbl1.Content = value;
53        }
54
55        /**//// <summary>
56        /// 调用的方法
57        /// </summary>
58        /// <param name="value"></param>
59        /// <returns></returns>
60        private string GetValue(string value)
61        {
62            Thread.Sleep(10000);
63            return "say:" + value;
64        }
65    }