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通信程序通常都是采用Client/Server形式。這就要求作為服務(wù)器的主機可以同時處理多個客戶的請求。因此在編寫服務(wù)器程序時要添加多個Winsock控件。在開始我們先加入兩個Winsock控件。其中一個用來偵聽網(wǎng)上請求信號，取名為Listener；另外一個為初始的連接口，取名叫Sock（0）。注意，后一個控件要設(shè)為動態(tài)數(shù)組的形式，以后當客戶增多時，可在這個控件基礎(chǔ)上動態(tài)增加。由于受資源限制，我們在本例中設(shè)定最多可以同時接納15個客戶。客戶機一般只與一個主機相連，因此程序只須一個Winsock進行連接就足夠了。這個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注釋。
******************************
服務(wù)器程序
******************************
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
Listener.LocalPort = 1011
‘開始偵聽
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15個，動態(tài)添加sock
If SockIndex > SockNum Then
Load Sock(SockIndex)
End If
ConnectState(SockIndex) = BUSY
Sock(SockIndex).Tag = SockIndex
接受請求
Sock(SockIndex).Accept (requestID)
Form1.Print SockIndex & "接受請求"
End Sub

客戶斷開，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

***************************
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()
遠程主機名
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