15.1 异步函数简介

15.1.1 初识异步类型

 1     public partial class AsyncForm : Form
 2     {
 3         Label label;
 4         Button button;
 5         public AsyncForm()
 6         {
 7             InitializeComponent();
 8             label = new Label { Location = new Point(10, 20), Text = "Length" };
 9             button = new Button { Location = new Point(10, 50), Text = "Click" };
10             button.Click += DisPlayWebSiteLength;
11             AutoSize = true;
12             Controls.Add(label);
13             Controls.Add(button);
14         }
15         async void DisPlayWebSiteLength(object sender, EventArgs e)
16         {
17             label.Text = "Fetching";
18             using (HttpClient client = new HttpClient())
19             {
20                 Task<string> task = client.GetStringAsync("https://www.baidu.com/");
21                 string text = await task;
22                 label.Text = text.Length.ToString();
23             }
24         }
25     }

15.1.2 分解第一个示例