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