SKY外语计算机学习

标题: 继续vb2008实现多线程的挂起和继续 [打印本页]

作者: SKY晓夜 时间: 2013-11-26 11:29
标题: 继续vb2008实现多线程的挂起和继续
作者：SKY晓夜　日期：2013-11-26　原文地址：http://www.skywj.com/thread-9446-1-1.html

完成了上一个多线程的例子，但是还纯在一个问题是，怎么使线程挂起和继续，注意这里说的不是停止，停止在上一节中已有演示。

要挂起多线程，vb中没有像vc中那样有直接的函数可以挂起制定线程，vb.net中使用ManualResetEvent类，来实现类似的功能，我姑且把他看做一个信号发射器，可以命令线程的挂起，和继续。

分别使用

Reset()发送挂起信号，挂起线程
set()发送继续信号，继续线程
有发送就有接收端，我们使用WaitOne()来接收这些信号
WaitOne()使用需要一定的技巧，看你放置的位置，主要不要放置在主界面线程。
WaitOne()接收到信号就会再相应的代码处挂起。

二楼上代码，还是使用上一片中的例子，加入两个按钮来实现挂起和继续。

作者: SKY晓夜 时间: 2013-11-26 11:30
本帖最后由 SKY晓夜于 2013-11-26 11:32 编辑

Imports System.Threading
Public Class Form1
#Region "Shared data"
Private mMin As Integer
Private mMax As Integer
Private mResults As New List(Of Integer)
Private value As Integer
    Dim Mr As ManualResetEvent = New ManualResetEvent(True)

#End Region
#Region "Primary Thread methods"
Private Sub btnStrat_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnStrat.Click
      ProgressBar1.Value = 0
      ListBox1.Items.Clear()
      mMin = 1
      mMax = 10000
      '启动后台线程
      BackgroundWorker1.RunWorkerAsync()
End Sub
Private Sub btnCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancel.Click
      BackgroundWorker1.CancelAsync()
End Sub
Private Sub BackgroundWorker1_ProgressChanged(ByVal sender As Object, ByVal e As System.ComponentModel.ProgressChangedEventArgs) Handles BackgroundWorker1.ProgressChanged
      '主线程

      ProgressBar1.Value = 100 + (e.ProgressPercentage)
End Sub
Private Sub BackgroundWorker1_RunWorkerCompleted(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles BackgroundWorker1.RunWorkerCompleted
      '后台线程完成是显示所有素数
      For Each item As String In mResults
         ListBox1.Items.Add(item)
      Next

End Sub
#End Region
'后台计算素数线程
#Region "Background Thread methods"
Private Sub BackgroundWorker1_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles BackgroundWorker1.DoWork
      mResults.Clear()
      For count As Integer = mMin To mMax Step 2
         Dim isPtime As Boolean = True
         For x As Integer = 1 To CInt(count / 2)
            For y As Integer = 1 To x
                  If x * y = count Then
                     isPtime = False
                      Mr.WaitOne()
                     Exit For
                  End If
            Next
            If Not isPtime Then Exit For
         Next
         If isPtime Then
            mResults.Add(count)
         End If
         Me.BackgroundWorker1.ReportProgress(CInt((count - mMax) / (mMax - mMin) * 100))
         If Me.BackgroundWorker1.CancellationPending Then
            Exit For
         End If
      Next
     Mr.WaitOne()
End Sub

#End Region

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
      Mr.Reset()
End Sub

Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click
      Mr.Set()
End Sub
End Class

作者: SKY晓夜 时间: 2013-11-26 11:33
主要红色代码，Mr.WaitOne() 位置可以自己调整来看效果，这里给出两个位置，供给调试。

作者: admin 时间: 2013-12-16 17:12
不错，以后多发这种技术贴！

欢迎光临 SKY外语计算机学习 (http://skywj.com/)