1 namespace demo
 2 {
 3     public partial class Form1 : Form
 4     {
 5         public Form1()
 6         {
 7             InitializeComponent();
 8         }
 9 
10         private void button1_Click(object sender, EventArgs e)
11         {
12             FileUploader f1 = new FileUploader();
13             f1.FileUploaded += ShowProcess;                  //绑定事件
14             ThreadPool.QueueUserWorkItem((a) => f1.Upload());//加入线程池
15         }
16 
17         private void ShowProcess(object sender, FileUploaderEventArgs e)
18         {
19             //定义委托
20             Action t = () =>
21             {
22                 progressBar1.Value = e.FileProgress;
23                 label1.Text = e.FileProgress.ToString();
24             };
25 
26             //跨线程操作
27             this.BeginInvoke(t); 
28             Thread.Sleep(500);
29         }
30     }
31 
32     /// <summary>
33     /// 文件下载类
34     /// </summary>
35     class FileUploader
36     {
37         public event EventHandler<FileUploaderEventArgs> FileUploaded;//定义事件
38         public void Upload()
39         {
40             var e = new FileUploaderEventArgs() { FileProgress = 0 };
41             while (e.FileProgress < 100)
42             {
43                 e.FileProgress++;
44                 FileUploaded(this, e);//触发事件
45             }
46         }
47     }
48 
49     /// <summary>
50     /// 自定义参数
51     /// </summary>
52     class FileUploaderEventArgs : EventArgs
53     {
54         public int FileProgress { get; set; }
55     }
56 }