多进程处理之BackgroundWorker

 

说明：通过本例对BackgroundWorker的WorkerReportsProgress,WorkerSupportsCancdllation属性及Dowork,ProessChanged,RunWorkerCompleted事件做进一步的了解。

 

 1   public partial class Form1 : Form

 2     {

 3         public Form1()

 4         {

 5             InitializeComponent();

 6 

 7             //获取或设置一个值，该值指示BW报告能否报告进度更新

 8             backgroundWorker1.WorkerReportsProgress = true;

 9             //获取或设置一个值，该值指示BW是否支持异步取消

10             backgroundWorker1.WorkerSupportsCancellation = true;

11             buttonStop.Enabled = false;

12         }

13 

14         private void buttonStart_Click(object sender, EventArgs e)

15         {

16             richTextBox1.Text = "开始产生10000以内的随机数……\n\n";

17             buttonStart.Enabled = false;

18             buttonStop.Enabled = true;

19             //在后台开始操作

20             backgroundWorker1.RunWorkerAsync();

21         }

22 

23         private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)

24         {

25             //不要直接使用组件实例名称（backgroundWorker1），因为有多

26             //个BackgroundWorker时，直接使用会产生耦合问题

27             //应该通过下面的转换使用它

28             BackgroundWorker worker = sender as BackgroundWorker;

29             //下面的内容相当于线程要处理的内容。注意：不要在此事件中和控件打交道

30             Random r = new Random();

31             int numCount = 0;

32             while (worker.CancellationPending == false)

33             {

34                 int num = r.Next(10000);

35                 if (num % 5 == 0)

36                 {

37                     numCount++;

38                     //引发BW.ProgressChanged()事件

39                     worker.ReportProgress(0, num);

40                     Thread.Sleep(1000);

41                 }

42             }

43             //DoworkEventArgs.Result 获取或设置表示异步操作结果的值

44             e.Result = numCount;

45         }

46 

47 

48         private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)

49         {

50             //object ProgressChangedEventArgs.UserState 获取唯一的用户状态

51             int num = (int)e.UserState;

52             richTextBox1.Text += num + ",";

53         }

54 

55         private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)

56         {

57             if (e.Error == null)

58             {

59                 richTextBox1.Text += "\n\n操作停止，共产生"+e.Result+"个能被5整除的随机数";

60             }

61             else

62             {

63                 richTextBox1.Text += "\n操作过程中产生错误：" + e.Error;

64             }

65            

66         }

67 

68         private void buttonStop_Click(object sender, EventArgs e)

69         {

70             //请求取消挂起后的操作

71             backgroundWorker1.CancelAsync();

72             buttonStop.Enabled = false;

73             buttonStart.Enabled = true;

74         }

75     }