VB.NET中采用多线程填写treeview控件

本文介绍了一个简单的应用程序,该程序能够利用多线程技术扫描指定文件夹及其子文件夹中的所有DLL文件,并将它们显示在一个树形视图中。通过使用多线程,程序能够在扫描过程中保持良好的用户体验。
功能:把选定文件夹下的dll、子文件夹和子文件夹中的dll填写到窗体的treeview控件上。

  缺点:窗体简单,代码有些混乱,线程之间的调用可能没有到最优化。

  实现:imagelist中的图片需要自己重新定义。

  多线程的优点:可以及时响应用户的操作,不至于产生“未响应”的尴尬;设计合理(结合需求)的话,可使软件的性能提高。

  多线程的编写:结构合理、注意同步。

  以上是我对这个例程和多线程的个人体会,如有不妥之处,还请大家批评指正。

Imports System.IO
Public Class Form1
Inherits System.Windows.Forms.Form

#Region " Windows 窗体设计器生成的代码 "

Public Sub New()
 MyBase.New()

 '该调用是 Windows 窗体设计器所必需的。
 InitializeComponent()

 '在 InitializeComponent() 调用之后添加任何初始化

End Sub

'窗体重写 dispose 以清理组件列表。
Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
 If disposing Then
  If Not (components Is Nothing) Then
   components.Dispose()
  End If
 End If
 MyBase.Dispose(disposing)
End Sub

'Windows 窗体设计器所必需的
Private components As System.ComponentModel.IContainer

 '注意: 以下过程是 Windows 窗体设计器所必需的
 '可以使用 Windows 窗体设计器修改此过程。
 '不要使用代码编辑器修改它。
 Friend WithEvents TreeView1 As System.Windows.Forms.TreeView
 Friend WithEvents btnOpenBrower As System.Windows.Forms.Button
 Friend WithEvents ImageList1 As System.Windows.Forms.ImageList
 <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
 Me.components = New System.ComponentModel.Container
 Dim resources As System.Resources.ResourceManager = New System.Resources.ResourceManager(GetType(Form1))
 Me.TreeView1 = New System.Windows.Forms.TreeView
 Me.ImageList1 = New System.Windows.Forms.ImageList(Me.components)
 Me.btnOpenBrower = New System.Windows.Forms.Button
 Me.SuspendLayout()
 '
 'TreeView1
 '
 Me.TreeView1.Dock = System.Windows.Forms.DockStyle.Left
 Me.TreeView1.ImageList = Me.ImageList1
 Me.TreeView1.Location = New System.Drawing.Point(0, 0)
 Me.TreeView1.Name = "TreeView1"
 Me.TreeView1.Size = New System.Drawing.Size(376, 581)
 Me.TreeView1.TabIndex = 0
 '
 'ImageList1
 '
 Me.ImageList1.ImageSize = New System.Drawing.Size(16, 16)
 Me.ImageList1.ImageStream = CType(resources.GetObject("ImageList1.ImageStream"), System.Windows.Forms.ImageListStreamer)
 Me.ImageList1.TransparentColor = System.Drawing.Color.Transparent
 '
 'btnOpenBrower
 '
 Me.btnOpenBrower.Location = New System.Drawing.Point(408, 64)
 Me.btnOpenBrower.Name = "btnOpenBrower"
 Me.btnOpenBrower.Size = New System.Drawing.Size(96, 23)
 Me.btnOpenBrower.TabIndex = 1
 Me.btnOpenBrower.Text = "Open Brower"
 '
 'Form1
 '
 Me.AutoScaleBaseSize = New System.Drawing.Size(6, 14)
 Me.ClientSize = New System.Drawing.Size(536, 581)
 Me.Controls.Add(Me.btnOpenBrower)
 Me.Controls.Add(Me.TreeView1)
 Me.Name = "Form1"
 Me.Text = "Form1"
 Me.ResumeLayout(False)

End Sub

#End Region
Private Sub OpenBrower()
 Dim f As New FolderBrowserDialog
 If f.ShowDialog = DialogResult.OK Then
  Me.TreeView1.Nodes.Clear()
  Me.SuspendLayout()
  Dim nodeTemp As TreeNode = CType(Me.Invoke(New AddTreeNodeHandler(AddressOf Me.AddFileToTreeview), New Object() {f.SelectedPath}), TreeNode)
  Me.AddFile(New DirectoryInfo(f.SelectedPath), nodeTemp)
  Me.ResumeLayout(False)
 End If
End Sub

Private Sub AddFile(ByVal dirPath As DirectoryInfo, ByVal node As TreeNode)
 Dim tempHandler As New AddFileHandler(AddressOf Me.AddFileToTreeNode)
 For Each dir As DirectoryInfo In dirPath.GetDirectories()
  Dim nodeTemp As TreeNode = CType(Me.Invoke(tempHandler, New Object() {dir.Name, CLASSIO.Directory, node}), TreeNode)
  Me.AddFile(dir, nodeTemp)
 Next
 For Each file As FileInfo In dirPath.GetFiles("*.dll")
  Me.Invoke(tempHandler, New Object() {file.Name, CLASSIO.File, node})
 Next
End Sub

Private Function AddFileToTreeNode(ByVal str As String, ByVal cls As CLASSIO, ByVal node As TreeNode) As TreeNode
 Dim nodeTemp As New TreeNode(str)
 nodeTemp.ImageIndex = CInt(cls)
 node.Nodes.Add(nodeTemp)
 nodeTemp.SelectedImageIndex = nodeTemp.ImageIndex
 Return nodeTemp
End Function

Private Function AddFileToTreeview(ByVal str As String) As TreeNode
 Dim nodeTemp As New TreeNode(str)
 Me.TreeView1.Nodes.Add(nodeTemp)
 Return nodeTemp
 nodeTemp.SelectedImageIndex = CInt(CLASSIO.Directory)
End Function

Private Sub btnOpenBrower_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOpenBrower.Click
 '多线程
 Dim t As Threading.Thread = New Threading.Thread(AddressOf Me.OpenBrower)
 t.Start()
 
 '单线程
 'Me.OpenBrower()
End Sub
End Class

Public Enum CLASSIO
 File = 1
 Directory = 0
End Enum

Public Delegate Function AddFileHandler(ByVal str As String, ByVal cls As CLASSIO, ByVal Node As TreeNode) As TreeNode
Public Delegate Function AddTreeNodeHandler(ByVal str As String) As TreeNode
在码农的生活中,很多级码农都有这样的经历,会被一个小小的技术问题拦住,然后进度跟不上了,被老板XXXX一大通了。心情不爽了。 好吧,这个曾经是我遇到拦路虎之一。但事实上不是什么大技术。技术就是一层纸,破了就破了。 这是一个关于如何跨窗体操作控件或过程的一个例子。比如,你想用窗体A的按键来执行窗体B的文本框变色。 Imports System Imports System.Threading Imports System.Text Public Class Form1 Private Sub Form1_Load(sender As Object, e As EventArgs) Handles Me.Load CheckForIllegalCrossThreadCalls = False '不写这行,会出错,不允许线程的数据写到TextBox1.Text 中去。 Form2.Show() End Sub Private Sub form1_FormClosing(sender As Object, e As EventArgs) Handles Me.FormClosing ' If runThread.IsAlive = True Then runThread.Abort() End Sub Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click '用的是委托方式 Me.Invoke(New MethodInvoker(AddressOf THREAD2)) End Sub Private Sub THREAD2() Static j As Integer j = j + 1 TextBox1.Text = " 这是 [线程] 操作" & vbCrLf & _ " Button2被点了: " & j & " 次" & vbCrLf & "要求是from2.textbox.text= textbox1.text 。[问题]但为什么不能成功显示呢?" End Sub Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged Form2.TextBox1.Text = TextBox1.Text End Sub Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click Static j As Integer j = j + 1 TextBox1.Text = " 这是 [非线程] 操作" & vbCrLf & _ "Button3 点击了: " & j & " 次" & vbCrLf & _ "要求是from2.textbox.text= textbox1.text, 可以成功显示,这个是对的。" End Sub End Class
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