VB如何獲取USB口條碼槍的掃描數(shù)據(jù)？

這么跟你說吧，條碼掃描器就相當于自動打字的鍵盤一樣，會把掃描到的條碼自動轉(zhuǎn)換為數(shù)字然后發(fā)送到電腦中。你打開記事本，然后掃描一些條碼試試就知道了。

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你的條碼掃描器的說明書應(yīng)該還有各種設(shè)置方法的說明的，可以給掃描器增添各種功能，比如在條碼數(shù)字的后面增加一個回車鍵，這在編程中比較有用。

vb.net中，讀取和寫入文件

寫入：Dim sr As New IO.StreamWriter(Application.StartupPath "/寫入的文本.txt")

sr.WriteLine("寫入的內(nèi)容") sr.Close()讀?。篒f (File.Exists(Application.StartupPath "/msg.txt")) Then

Dim fm As New IO.FileStream(Application.StartupPath "/讀取的文本.txt", FileMode.Open)

Dim sr As IO.StreamReader = New IO.StreamReader(fm)

Do While sr.Peek() = 0

TextBox1.Text = sr.ReadLine() （讀取文本到文本框）

Loop end if

VB.NET檢測插入U盤時執(zhí)行某段代碼，并能獲取U盤盤符

以下內(nèi)容為網(wǎng)絡(luò)提供,但我自己驗證可行,供你參考.

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盤插入

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盤已插入！盤符為:" + 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盤卸載

ListBox1.Items.Add("U盤卸載！")

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("請您現(xiàn)在插入U盤至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("請選擇U盤盤符！", 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，請輸入要保存的字符串", "輸入信息", "Input then Test String! hehe!"))

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

Catch ex As Exception

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

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("請選擇U盤盤符！", 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 失敗")

Finally

If Reader IsNot Nothing Then Reader.Close()

End Try

End If

End Sub

End Class

關(guān)于VB和USB

如果是USB轉(zhuǎn)串口，那么還用mscomm控件，如果不是，那就問生產(chǎn)廠家要通訊協(xié)議。

VB.NET怎樣把USB攝像頭在顯示器上輸出的實時畫面（像素信息），引入到數(shù)據(jù)庫.

用directshow獲取幀緩存,轉(zhuǎn)換為標準圖像格式(比如jpg,png這些),存儲到數(shù)據(jù)庫的image字段里就行了.

vb.net 讀取掃描槍USB接口數(shù)據(jù)的實例

USB比較難抓數(shù)據(jù)，建議是USB模擬串口，或者直接就是串口，這樣數(shù)據(jù)比較好抓。

USB上傳模式是鼠標光標在哪數(shù)據(jù)就上傳在哪，所以你抓USB的數(shù)據(jù)的很難！

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