fudpexample.frm

在Windows下用WinSock API开发的示例

VERSION 5.00
Begin VB.Form fUdpExample 
   BorderStyle     =   1  'Fixed Single
   Caption         =   "Winsock API Demo (UDP Example)"
   ClientHeight    =   4920
   ClientLeft      =   45
   ClientTop       =   330
   ClientWidth     =   5790
   LinkTopic       =   "Form1"
   MaxButton       =   0   'False
   MinButton       =   0   'False
   ScaleHeight     =   4920
   ScaleWidth      =   5790
   StartUpPosition =   3  'Windows Default
   Begin VB.CommandButton cmdClose 
      Caption         =   "&Close"
      Height          =   375
      Left            =   4560
      TabIndex        =   4
      Top             =   4440
      Width           =   1095
   End
   Begin VB.TextBox txtClient 
      Height          =   1695
      Left            =   120
      MultiLine       =   -1  'True
      ScrollBars      =   2  'Vertical
      TabIndex        =   3
      Top             =   2520
      Width           =   5535
   End
   Begin VB.TextBox txtServer 
      Height          =   1695
      Left            =   120
      MultiLine       =   -1  'True
      ScrollBars      =   2  'Vertical
      TabIndex        =   2
      Top             =   360
      Width           =   5535
   End
   Begin VB.Label lblClientSocket 
      Caption         =   "Client socket handle:"
      Height          =   255
      Left            =   120
      TabIndex        =   1
      Top             =   2160
      Width           =   4575
   End
   Begin VB.Label lblServerSocket 
      Caption         =   "Server socket handle:"
      Height          =   255
      Left            =   120
      TabIndex        =   0
      Top             =   120
      Width           =   4575
   End
End
Attribute VB_Name = "fUdpExample"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
'
' ---------------------------------------------------------------------------------
' File...........: fUdpExample.frm
' Author.........: Will Barden
' Created........: 04/06/03
' Modified.......: 04/07/03
' Version........: 1.0
' Website........: http://www.WinsockVB.com
' Contact........: [e-mail]
'
' A simple form to demonstrate sending and receiving data with UDP.
' ---------------------------------------------------------------------------------
'
' ---------------------------------------------------------------------------------
' Form events.
' ---------------------------------------------------------------------------------
'
Private Sub Form_Load()
   '
Dim udtData       As WSADATA
Dim hServerSocket As Long
Dim hClientSocket As Long
Dim udtLocal      As sockaddr_in
Dim udtRemote     As sockaddr_in
Dim udtBlank      As sockaddr_in
Dim strData       As String
Dim bytData()     As Byte
Dim bytData2()    As Byte
Dim lngCount      As Long
   '
   ' Start Winsock 2 and check the return for errors.
   If (WSAStartup(WINSOCK_V2_2, udtData) = SOCKET_ERROR) Then
      Call MsgBox("WSAStartup() failed")
   Else
      '
      ' Create a server socket - this will be used for receiving UDP data.
      Call LogServer("1. Creating server socket")
      hServerSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)
      If (hServerSocket = INVALID_SOCKET) Then
         Call LogServer("Socket creation failed")
         Call WSACleanup
         Exit Sub
      End If
      '
      ' Create the client socket, this will be used for sending UDP data.
      Call LogClient("2. Creating client socket")
      hClientSocket = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP)
      If (hClientSocket = INVALID_SOCKET) Then
         Call LogClient("Socket creation failed")
         Call closesocket(hServerSocket)
         Call WSACleanup
         Exit Sub
      End If
      '
      ' Setup a sockaddr_in to point to the localhost, and bind the server socket.
      Call LogServer("3. Binding server socket to local addresses")
      With udtLocal
         .sin_family = AF_INET
         .sin_addr.s_addr = vbInetAddr(INADDR_ANY)
         .sin_port = htons(10101)
      End With
      Call bind(hServerSocket, udtLocal, LenB(udtLocal))
      '
      ' Prepare a byte array with the data we want to send, and count the bytes.
      Call LogClient("4. Sending data")
      strData = "Isn't the Winsock API great?"
      bytData = StrConv(strData, vbFromUnicode)
      lngCount = UBound(bytData) - LBound(bytData) + 1
      '
      ' Send the data to the local machine. To alter where this data is sent to,
      ' simply change the s_addr and sin_port fields of the sockaddr_in structure.
      With udtRemote
         .sin_family = AF_INET
         .sin_addr.s_addr = vbInetAddr("127.0.0.1")
         .sin_port = htons(10101)
      End With
      Call sendto(hClientSocket, bytData(0), lngCount, 0&, udtRemote, LenB(udtRemote))
      '
      ' Prepare a byte array to receive on the server socket, and call recvfrom().
      ReDim bytData2(0 To 1023)
      lngCount = UBound(bytData2) - LBound(bytData2) + 1
      Call recvfrom(hServerSocket, bytData2(0), lngCount, 0&, udtBlank, LenB(udtBlank))
      Call LogServer("5. Received: " & StrConv(bytData2, vbUnicode))
      '
      ' Clean up the socket handles, and free the Winsock DLL.
      Call closesocket(hServerSocket)
      Call closesocket(hClientSocket)
      '
      Call WSACleanup
      '
   End If
   '
End Sub
'
' ---------------------------------------------------------------------------------
' Control events.
' ---------------------------------------------------------------------------------
'
Private Sub cmdClose_Click()
   '
   Call Unload(Me)
   '
End Sub
'
' ---------------------------------------------------------------------------------
' Private helpers.
' ---------------------------------------------------------------------------------
'
Private Sub LogClient(ByVal strText As String)
   '
   With txtClient
      .SelStart = Len(.Text)
      .SelText = strText & vbCrLf
      .SelStart = Len(.Text)
   End With
   '
End Sub
'
Private Sub LogServer(ByVal strText As String)
   '
   With txtServer
      .SelStart = Len(.Text)
      .SelText = strText & vbCrLf
      .SelStart = Len(.Text)
   End With
   '
End Sub
'
' ---------------------------------------------------------------------------------
' EOF.
' ---------------------------------------------------------------------------------
'