通信程序通常都是采用Client/Server形式。這就要求作為服務(wù)器的主機(jī)可以同時(shí)處理多個(gè)客戶的請(qǐng)求。因此在編寫服務(wù)器程序時(shí)要添加多個(gè)Winsock控件。在開(kāi)始我們先加入兩個(gè)Winsock控件。其中一個(gè)用來(lái)偵聽(tīng)網(wǎng)上請(qǐng)求信號(hào)，取名為L(zhǎng)istener；另外一個(gè)為初始的連接口，取名叫Sock（0）。注意，后一個(gè)控件要設(shè)為動(dòng)態(tài)數(shù)組的形式，以后當(dāng)客戶增多時(shí)，可在這個(gè)控件基礎(chǔ)上動(dòng)態(tài)增加。由于受資源限制，我們?cè)诒纠性O(shè)定最多可以同時(shí)接納15個(gè)客戶?？蛻魴C(jī)一般只與一個(gè)主機(jī)相連，因此程序只須一個(gè)Winsock進(jìn)行連接就足夠了。這個(gè)程序要用到的控件較少，除了Winsock和Form控件外，只須再添加Commmand控件即可。下面是具體程序和詳細(xì)注釋。
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服務(wù)器程序
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Option Explicit
定義常量
Const BUSY As Boolean = False
Const FREE As Boolean = True
定義連接狀態(tài)
Dim ConnectState() As Boolean
Private Sub Form_Load()
ReDim Preserve ConnectState(0 To 1)
On Error Resume Next
ConnectState(0) = FREE
ConnectState(1) = FREE
’指定網(wǎng)絡(luò)端口號(hào)
Listener.LocalPort = 1011
‘開(kāi)始偵聽(tīng)
Listener.Listen
End Sub
Private Sub Listener_ConnectionRequest(ByVal requestID As Long)
Dim SockIndex As Integer
Dim SockNum As Integer
On Error Resume Next
Form1.Print requestID & "連接請(qǐng)求"
查找連接的用戶數(shù)
SockNum = UBound(ConnectState)
If SockNum > 14 Then
Form1.Print SockIndex & ""
Exit Sub
End If
查找空閑的sock
SockIndex = FindFreeSocket()
’如果已有的sock都忙，而且sock數(shù)不超過(guò)15個(gè)，動(dòng)態(tài)添加sock
If SockIndex > SockNum Then
Load Sock(SockIndex)
End If
ConnectState(SockIndex) = BUSY
Sock(SockIndex).Tag = SockIndex
接受請(qǐng)求
Sock(SockIndex).Accept (requestID)
Form1.Print SockIndex & "接受請(qǐng)求"
End Sub

客戶斷開(kāi)，關(guān)閉相應(yīng)的sock
Private Sub Sock_Close(Index As Integer)
If Sock(Index).State <> sckClosed Then
Sock(Index).Close
End If
ConnectState(Index) = FREE
Form1.Print Index & "close"
End Sub

接收數(shù)據(jù)
Private Sub Sock_DataArrival(Index As Integer, ByVal bytesTotal As Long)
Dim dx As Double
Form1.Print "數(shù)據(jù)來(lái)自" & Index
Sock(Index).GetData dx, vbDouble
Form1.Print "dx=" & dx
End Sub

尋找空閑的sock
Public Function FindFreeSocket()
Dim SockCount, i As Integer
SockCount = UBound(ConnectState)
For i = 0 To SockCount
If ConnectState(i) = FREE Then
FindFreeSocket = i
Exit Function
End Ifs
Next i
ReDim Preserve ConnectState(0 To SockCount + 1)
FindFreeSocket = UBound(ConnectState)
End Function

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客戶程序
’***************************
Option Explicit
發(fā)送數(shù)據(jù)
Private Sub command1_Click()
Dim dx As Double
dx = 23.9
sock.SendData dx
MsgBox ("data sended")
End Sub

Private Sub Form_Load()
遠(yuǎn)程主機(jī)名
sock.RemoteHost = "media2"
網(wǎng)絡(luò)端口
sock.RemotePort = 1011
發(fā)出連接命令
sock.Connect
Command1.Enabled = False
End Sub

服務(wù)器關(guān)閉
Private Sub sock_Close()
MsgBox ("socket closed")
End Sub

連接成功
Private Sub sock_Connect()
MsgBox ("socket connected")
Command1.Enabled = True
End Sub