陳 翀

摘要在VB語(yǔ)言設(shè)計(jì)中 Winsock控件對(duì)用戶(hù)是不可視的,可以很容易地訪(fǎng)問(wèn)TCP和UDP網(wǎng)絡(luò)服務(wù)。要編寫(xiě)客戶(hù)和服務(wù)器應(yīng)用程序,不需要了解TCP或調(diào)用底層Winsock API的具體細(xì)節(jié)。通過(guò)設(shè)置Winsock控件的屬性和調(diào)用該控件的方法,可以很容易地連接到遠(yuǎn)程計(jì)算機(jī)并進(jìn)行雙向的數(shù)據(jù)交換。

關(guān)鍵詞VB Winsock

中圖分類(lèi)號(hào):TP3文獻(xiàn)標(biāo)識(shí)碼:A

1 VB語(yǔ)言的簡(jiǎn)介

20世紀(jì)70年代末,Microsoft在當(dāng)時(shí)的PC機(jī)上開(kāi)發(fā)了第一代的Basic語(yǔ)言,隨著Windows操作系統(tǒng)的不斷成熟,Visual Basic產(chǎn)品由1.0版升級(jí)到3.0版,此時(shí) Visual Basic已初具規(guī)模了。

隨著Internet的迅猛發(fā)展,Microsoft的ActiveX技術(shù)出現(xiàn)了,并被不失時(shí)機(jī)地加入到 Visual Basic 5.0版本中(1997年)。在1998年,Microsoft推出了Visual Basic 6.0版本,這一版本使VB得到了很大的擴(kuò)充和增強(qiáng)。它還引入了使用部件編程的概念。迄今為止,Visual Basic已經(jīng)發(fā)展成為快速應(yīng)用程序開(kāi)發(fā)工具的代表。

2 連接測(cè)試

此程序分別安裝在兩臺(tái)不同計(jì)算機(jī)上,并連接在LAN上,一臺(tái)為主機(jī),一臺(tái)為客戶(hù)機(jī)。主機(jī)一直監(jiān)聽(tīng)所設(shè)定的端口?？蛻?hù)機(jī)上設(shè)主機(jī)的IP,設(shè)好主機(jī)端口,點(diǎn)擊連接鍵,客戶(hù)機(jī)就與主機(jī)連接。并可互相發(fā)送信息。

2.1 設(shè)法連接主機(jī)

Private Sub cmdConnnect_Click()

cmdListen.Enabled = False

WinsockConnectTest.Close

WinsockConnectTest.Connect txtIPaddress.Text, txtTestPort

lblConnectionStatus.Caption = "通過(guò)端口 " & txtTestPort.Text & " 連接 " & txtIPaddress.Text & "<|||>" & "Connecting to " & txtIPaddress.Text & " on port " & txtTestPort.Text

Timer1.Enabled = True

End Sub

2.2 監(jiān)聽(tīng)試圖連接你的主機(jī)

Private Sub cmdListen_Click()cmdConnnect.Enabled = False

WinsockConnectTest.Close

WinsockConnectTest.LocalPort = txtTestPort.Text

WinsockConnectTest.Listen

lblConnectionStatus.Caption = "正在監(jiān)聽(tīng)/Listening on port " & txtTestPort.Text

End Sub

2.3 檢查網(wǎng)絡(luò)是否連接

Private Sub lblCheckConnection_Click()

If Not WinsockConnectTest.State = 7 Then

lblCheckConnection.Caption = "連接/Connected: 否/No"

Else

lblCheckConnection.Caption = "連接/Connected: 是/Yes"

End If

End Sub

2.4 當(dāng)客戶(hù)機(jī)試圖連接主機(jī)時(shí),程序?qū)㈥P(guān)注連接狀態(tài)

Private Sub Timer1_Timer() '

If Not WinsockConnectTest.State = 7 Then

lblConnectionStatus.Caption = "連接失敗/Connection Failed"

WinsockConnectTest.Close

cmdConnnect.Enabled = True

cmdListen.Enabled = True

Timer1.Enabled = False

Else

If cmdListen.Enabled = True Then

lblConnectionStatus.Caption = "連接/Connected"

End If

End If

End Sub

2.5 當(dāng)連接時(shí),WinsockConnectTest.SendData將數(shù)據(jù)發(fā)送出去

Private Sub cmdSendDataServer_Click()

If WinsockConnectTest.State = 7 Then

Dim SendDataServer As String

SendDataServer = txtSendData.Text

WinsockConnectTest.SendData SendDataServer

Else

Beep

End If

End Sub

2.6 當(dāng)接收到數(shù)據(jù)時(shí),WinsockConnectTest.GetData將數(shù)據(jù)轉(zhuǎn)為字符,并顯示

Private Sub WinsockConnectTest_DataArrival(ByVal bytesTotal As Long)

Dim ServerData As String

WinsockConnectTest.GetData ServerData, (下轉(zhuǎn)第186頁(yè))(上接第182頁(yè))vbString

txtDataServer.SelStart = Len(txtDataServer.Text)

txtDataServer.SelText = ServerData & vbCrLf

End Sub

3 端口掃描

本程序的這個(gè)功能為掃描當(dāng)前所打開(kāi)的端口,并將其端口號(hào)顯示在列表中。在“主機(jī)IP地址”框中設(shè)置好要主機(jī)IP。選擇是本地還是互聯(lián)網(wǎng)掃描,設(shè)置所要掃描端口的范圍和掃描速度。點(diǎn)擊掃描運(yùn)行程序:

掃描端口主要代碼

Private Sub CmdScan_Click()

PortLow = txtPortLow.Text '起始端口號(hào)

PortHigh = txtPortHigh.Text '中止端口號(hào)

TimerScanner.Enabled = False

If Pause = True Then

lblShowsatwhatPort.Caption = "端口號(hào)/Port: " & AtPort & " 暫停/Pause"

Exit Sub

End If

If Start = "No" Then

Exit Sub

End If

If AtPort = PortHigh Then '檢查是否掃描到所設(shè)定的最后一個(gè)端口:

Exit Sub

End If

CmdScan.Enabled = False

If optLocal.Value = True Then '如果這個(gè)為本地掃描,另一個(gè)則為互聯(lián)網(wǎng)掃描:

Do

If Start = "No" Then

Exit Sub

End If

WinsockPortScanner.Close

DoEvents

WinsockPortScanner.Connect txtIPHostscanner.Text, AtPort

DoEvents

參考文獻(xiàn)

[1] 龔沛曾,陸慰民,楊志強(qiáng).Visual Basic程序設(shè)計(jì)教程.高等教育出版社,2000.7.

[2] 鄧文新,張桂香.Visual Basic程序設(shè)計(jì)方法.北京航空航天大學(xué)出版社,2003.1.