VB.NET检测插入U盘时执行某段代码，并能获取U盘盘符

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Imports System.IO

Public Class Form1

Public Const WM_DEVICECHANGE = H219

Public Const DBT_DEVICEARRIVAL = H8000

Public Const DBT_CONFIGCHANGECANCELED = H19

Public Const DBT_CONFIGCHANGED = H18

Public Const DBT_CUSTOMEVENT = H8006

Public Const DBT_DEVICEQUERYREMOVE = H8001

Public Const DBT_DEVICEQUERYREMOVEFAILED = H8002

Public Const DBT_DEVICEREMOVECOMPLETE = H8004

Public Const DBT_DEVICEREMOVEPENDING = H8003

Public Const DBT_DEVICETYPESPECIFIC = H8005

Public Const DBT_DEVNODES_CHANGED = H7

Public Const DBT_QUERYCHANGECONFIG = H17

Public Const DBT_USERDEFINED = HFFFF

Protected Overrides Sub WndProc(ByRef m As System.Windows.Forms.Message)

If m.Msg = WM_DEVICECHANGE Then

Select Case m.WParam

Case WM_DEVICECHANGE

Case DBT_DEVICEARRIVAL 'U盘插入

ComboBox1.Items.Clear()

Dim s() As DriveInfo = DriveInfo.GetDrives

For Each drive As DriveInfo In s

If drive.DriveType = DriveType.Removable Then

ListBox1.Items.Add("U盘已插入！盘符为:" + drive.Name.ToString())

ComboBox1.Items.Add(drive.Name)

End If

Next

BtnWrite.Enabled = True

BtnRead.Enabled = True

Case DBT_CONFIGCHANGECANCELED

Case DBT_CONFIGCHANGED

Case DBT_CUSTOMEVENT

Case DBT_DEVICEQUERYREMOVE

Case DBT_DEVICEQUERYREMOVEFAILED

Case DBT_DEVICEREMOVECOMPLETE 'U盘卸载

ListBox1.Items.Add("U盘卸载！")

BtnWrite.Enabled = False

BtnRead.Enabled = False

Case DBT_DEVICEREMOVEPENDING

Case DBT_DEVICETYPESPECIFIC

Case DBT_DEVNODES_CHANGED

Case DBT_QUERYCHANGECONFIG

Case DBT_USERDEFINED

End Select

End If

MyBase.WndProc(m)

End Sub

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

ListBox1.Items.Add("请您现在插入U盘至USB接口！")

End Sub

Private Sub BtnWrite_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnWrite.Click

If ComboBox1.Text = "" Then

MsgBox("请选择U盘盘符！", MsgBoxStyle.Exclamation, "Warn")

Else

Dim Writer As StreamWriter = Nothing

Try

Dim fileName As String = ComboBox1.Text + "Test.txt"

Writer = New StreamWriter(fileName)

Writer.WriteLine(InputBox("老四，请输入要保存的字符串", "输入信息", "Input then Test String! hehe!"))

MsgBox("Write to " + fileName + " Success!")

Catch ex As Exception

MsgBox(ex.Message, MsgBoxStyle.Critical, "Write 失败")

Finally

If Writer IsNot Nothing Then Writer.Close()

End Try

End If

End Sub

Private Sub BtnRead_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnRead.Click

If ComboBox1.Text = "" Then

MsgBox("请选择U盘盘符！", MsgBoxStyle.Exclamation, "Warn")

Else

Dim Reader As StreamReader = Nothing

Try

Dim fileName As String = ComboBox1.Text + "Test.txt"

Reader = New StreamReader(fileName)

MsgBox("Read from " + fileName + vbCrLf + Reader.ReadToEnd, MsgBoxStyle.Information, "Info")

Catch ex As Exception

MsgBox(ex.Message, MsgBoxStyle.Critical, "Read 失败")

Finally

If Reader IsNot Nothing Then Reader.Close()

End Try

End If

End Sub

End Class

vb.net中怎样让窗口加载以后立刻执行一遍time_tick中的代码，现在都是启动一段时间后才执行

这个，timer事件实际上都是时间达到设定的频率（Interval）时触发的，所以，要想达到程序启动立即触发的效果，建议把timer中事件写到一个函数（sub）中，然后在load和timer事件中调用该sub。

关于VB.NET进度条的实例

该实例有很多实现方法,下面介绍一种不同的给你:

首先要在窗体中载入以下控件:progressbar(进度条),label(用来实时显示文本提示),两个timer(分别控制进度条进度的增减),然后用以下代码就能实现:

Public Class Form1

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load

Timer1.Enabled = True

Timer1.Interval = 500

Timer2.Interval = 500

ProgressBar1.Value = 0

ProgressBar1.Maximum = 100

ProgressBar1.Minimum = 0

End Sub

'上述过程是设置控件的初始值,也可以在属性面板设置

Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer1.Tick

ProgressBar1.Value += 1

Label1.Text = "当前完成" ProgressBar1.Value "%"

If (ProgressBar1.Value = 100) Then

Timer1.Enabled = False

Timer2.Enabled = True

End If

End Sub

'timer1用来控制进度的增加

Private Sub Timer2_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Timer2.Tick

ProgressBar1.Value -= 1

Label1.Text = "当前完成" ProgressBar1.Value "%"

If (ProgressBar1.Value = 0) Then

Timer1.Enabled = True

Timer2.Enabled = False

End If

End Sub

'time2用来控制进度的减少

End Class

vb.net的，按键连续触发事件，比如，按着键不放，音量增大。

1.定义变量记录键是否被按下，按下的累计时间

Dim 按下A键  As Boolean

Dim 按下A键时间 As Integer

2.添加一个TextBox1用于接收键盘事件，或者直接用窗体的键盘事件(确保KeyPreview为True)

在KeyDown事件中添加如下代码：

If e.Keycode = keys.A Then 按下A键 = True

在KeyUp事件中添加如下代码：

If e.Keycode = keys.A Then 按下A键 = False

3.添加一个Timer1控件，调整Timer1的Interval来决定按键频率，记得要把Timer1.Enable开启

在Tick事件中添加如下代码：

If 按下A键 = True

按下A键时间+=1

Call 音量设置(按下A键时间 * 10)

End If

PS: 按下的秒数 = 按下A键时间*Timer1.Interval / 1000

VB.net module中如何使用计时器？

控制台调用Timer和窗体是类似的。首先在项目引用里面加入System.Windows.Forms程序集，然后在代码顶部引入命名空间：

Imports System.Windows.Forms

在控制台的Module中声明一个计时器：

Private WithEvents Timer1 As New Timer()

把计时器的Tick事件静态绑定到处理函数中：

Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick

'一些代码

End Sub

在需要开始计时的地方，修改其Interval、Enabled属性：

Timer1.Interval = 1000

Timer1.Enabled = True

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