VB中怎样检测是否在线，越简单越好

使用inet控件
Option ExplicitPrivate Sub Command1_Click()
    Command1.Enabled = False
    txStatus.Text = ""    If Len(Inet1.OpenURL("http://www.hinet.net")) <> 0 Or _
        Len(Inet1.OpenURL("http://www.altavista.com")) <> 0 Or _
        Len(Inet1.OpenURL("http://www.microsoft.com")) <> 0 Then

        txStatus.Text = "已经与 Internet 连接"
    Else
        txStatus.Text = "尚未与 Internet 连接"
    End If

    Command1.Enabled = True
End Sub

使用pingOption ExplicitPrivate Declare Function IcmpCreateFile Lib "icmp.dll" () As Long
Private Declare Function IcmpCloseHandle Lib "icmp.dll" (ByVal IcmpHandle As Long) As Long
Private Declare Function IcmpSendEcho Lib "icmp.dll" (ByVal IcmpHandle As Long, ByVal DestinationAddress As Long, ByVal RequestData As String, ByVal RequestSize As Long, ByVal RequestOptions As Long, ReplyBuffer As ICMP_ECHO_REPLY, ByVal ReplySize As Long, ByVal Timeout As Long) As Long
Private Declare Function WSAGetLastError Lib "WSOCK32.DLL" () As Long
Private Declare Function WSAStartup Lib "WSOCK32.DLL" (ByVal wVersionRequired As Long, lpWSADATA As WSADATA) As Long
Private Declare Function WSACleanup Lib "WSOCK32.DLL" () As Long'  ICMP返回的报文信息常数和Winsock版本等相关常数
Private Const IP_STATUS_BASE = 11000
Private Const IP_SUCCESS = 0
Private Const IP_BUF_TOO_SMALL = (11000 + 1)
Private Const IP_DEST_NET_UNREACHABLE = (11000 + 2)
Private Const IP_DEST_HOST_UNREACHABLE = (11000 + 3)
Private Const IP_DEST_PROT_UNREACHABLE = (11000 + 4)
Private Const IP_DEST_PORT_UNREACHABLE = (11000 + 5)
Private Const IP_NO_RESOURCES = (11000 + 6)
Private Const IP_BAD_OPTION = (11000 + 7)
Private Const IP_HW_ERROR = (11000 + 8)
Private Const IP_PACKET_TOO_BIG = (11000 + 9)
Private Const IP_REQ_TIMED_OUT = (11000 + 10)
Private Const IP_BAD_REQ = (11000 + 11)
Private Const IP_BAD_ROUTE = (11000 + 12)
Private Const IP_TTL_EXPIRED_TRANSIT = (11000 + 13)
Private Const IP_TTL_EXPIRED_REASSEM = (11000 + 14)
Private Const IP_PARAM_PROBLEM = (11000 + 15)
Private Const IP_SOURCE_QUENCH = (11000 + 16)
Private Const IP_OPTION_TOO_BIG = (11000 + 17)
Private Const IP_BAD_DESTINATION = (11000 + 18)
Private Const IP_ADDR_DELETED = (11000 + 19)
Private Const IP_SPEC_MTU_CHANGE = (11000 + 20)
Private Const IP_MTU_CHANGE = (11000 + 21)
Private Const IP_UNLOAD = (11000 + 22)
Private Const IP_ADDR_ADDED = (11000 + 23)
Private Const IP_GENERAL_FAILURE = (11000 + 50)
Private Const MAX_IP_STATUS = 11000 + 50
Private Const IP_PENDING = (11000 + 255)
Private Const PING_TIMEOUT = 200
Private Const WS_VERSION_REQD = &H101
Private Const WS_VERSION_MAJOR = WS_VERSION_REQD \ &H100 And &HFF&
Private Const WS_VERSION_MINOR = WS_VERSION_REQD And &HFF&
Private Const MIN_SOCKETS_REQD = 1
Private Const SOCKET_ERROR = -1
Private Const MAX_WSADescription = 256
Private Const MAX_WSASYSStatus = 128'   ICMP选项结构
Private Type ICMP_OPTIONS
    Ttl             As Byte
    Tos             As Byte
    Flags           As Byte
    OptionsSize     As Byte
    OptionsData     As Long
End Type'   ICMP应答结构
Private Type ICMP_ECHO_REPLY
    Address         As Long
    status          As Long
    RoundTripTime   As Long
    DataSize        As Long
    DataPointer     As Long
    Options         As ICMP_OPTIONS
    Data            As String * 250
End Type'  存放Winsock版本等信息的结构
Private Type WSADATA
    wVersion As Integer
    wHighVersion As Integer
    szDescription(0 To MAX_WSADescription) As Byte
    szSystemStatus(0 To MAX_WSASYSStatus) As Byte
    wMaxSockets As Long
    wMaxUDPDG As Long
    dwVendorInfo As Long
End TypeDim ICMPOPT As ICMP_OPTIONS'  返回状态信息
Private Function GetStatusCode(status As Long) As String
   Dim msg As String
   Select Case status
      Case IP_SUCCESS:               msg = "ip success"
      Case IP_BUF_TOO_SMALL:         msg = "ip buf too_small"
      Case IP_DEST_NET_UNREACHABLE:  msg = "ip dest net unreachable"
      Case IP_DEST_HOST_UNREACHABLE: msg = "ip dest host unreachable"
      Case IP_DEST_PROT_UNREACHABLE: msg = "ip dest prot unreachable"
      Case IP_DEST_PORT_UNREACHABLE: msg = "ip dest port unreachable"
      Case IP_NO_RESOURCES:          msg = "ip no resources"
      Case IP_BAD_OPTION:            msg = "ip bad option"
      Case IP_HW_ERROR:              msg = "ip hw_error"
      Case IP_PACKET_TOO_BIG:        msg = "ip packet too_big"
      Case IP_REQ_TIMED_OUT:         msg = "ip req timed out"
      Case IP_BAD_REQ:               msg = "ip bad req"
      Case IP_BAD_ROUTE:             msg = "ip bad route"
      Case IP_TTL_EXPIRED_TRANSIT:   msg = "ip ttl expired transit"
      Case IP_TTL_EXPIRED_REASSEM:   msg = "ip ttl expired reassem"
      Case IP_PARAM_PROBLEM:         msg = "ip param_problem"
      Case IP_SOURCE_QUENCH:         msg = "ip source quench"
      Case IP_OPTION_TOO_BIG:        msg = "ip option too_big"
      Case IP_BAD_DESTINATION:       msg = "ip bad destination"
      Case IP_ADDR_DELETED:          msg = "ip addr deleted"
      Case IP_SPEC_MTU_CHANGE:       msg = "ip spec mtu change"
      Case IP_MTU_CHANGE:            msg = "ip mtu_change"
      Case IP_UNLOAD:                msg = "ip unload"
      Case IP_ADDR_ADDED:            msg = "ip addr added"
      Case IP_GENERAL_FAILURE:       msg = "ip general failure"
      Case IP_PENDING:               msg = "ip pending"
      Case PING_TIMEOUT:             msg = "ping timeout"
      Case Else:                     msg = "unknown  msg returned"
   End Select
   GetStatusCode = CStr(status) & "   [ " & msg & " ]"
End Function'  获得一个整数的高字节位
Private Function HiByte(ByVal wParam As Long) As Integer
    HiByte = wParam \ &H100 And &HFF&
End Function'  获得一个整数的低字节位
Private Function LoByte(ByVal wParam As Long) As Integer
    LoByte = wParam And &HFF&
End Function

'  Ping一个IP地址
Private Function Ping(szAddress As String, ECHO As ICMP_ECHO_REPLY) As Long
    Dim hPort As Long
    Dim dwAddress As Long
    Dim sDataToSend As String
    Dim iOpt As Long
    sDataToSend = "Echo This"
    dwAddress = AddressStringToLong(szAddress)
    hPort = IcmpCreateFile()
    If IcmpSendEcho(hPort, dwAddress, sDataToSend, Len(sDataToSend), 0, ECHO, Len(ECHO), PING_TIMEOUT) Then
        '如果ping成功，状态返回0。
         Ping = ECHO.RoundTripTime
    Else
        Ping = ECHO.status * -1
    End If
    Call IcmpCloseHandle(hPort)
End Function

'  将文本框中的IP地址转换成系统识别的长整数形式
Function AddressStringToLong(ByVal tmp As String) As Long
    Dim i As Integer
    Dim parts(1 To 4) As String
    i = 0
    '转换IP地址
    While InStr(tmp, ".") > 0
        i = i + 1
        parts(i) = Mid(tmp, 1, InStr(tmp, ".") - 1)
        tmp = Mid(tmp, InStr(tmp, ".") + 1)
    Wend
    i = i + 1
    parts(i) = tmp
    If i <> 4 Then
        AddressStringToLong = 0
        Exit Function
    End If
    AddressStringToLong = Val("&H" & Right("00" & Hex(parts(4)), 2) & Right("00" & Hex(parts(3)), 2) & Right("00" & Hex(parts(2)), 2) & Right("00" & Hex(parts(1)), 2))
End Function'  初始化Socket
Private Function SocketsInitialize() As Boolean
    Dim WSAD As WSADATA
    Dim X As Integer
    Dim szLoByte As String
    Dim szHiByte As String
    Dim szBuf As String

    '初始化Socket
    X = WSAStartup(WS_VERSION_REQD, WSAD)
    If X <> 0 Then
        MsgBox "Windows Sockets for 32 bit Windows " & "environments is not successfully responding."
        Exit Function
    End If

     '  判断是否有支持足够的Socket
    If LoByte(WSAD.wVersion) < WS_VERSION_MAJOR Or (LoByte(WSAD.wVersion) = WS_VERSION_MAJOR And HiByte(WSAD.wVersion) < WS_VERSION_MINOR) Then
        szHiByte = Trim$(Str$(HiByte(WSAD.wVersion)))
        szLoByte = Trim$(Str$(LoByte(WSAD.wVersion)))
        szBuf = "Windows Sockets Version " & szLoByte & "." & szHiByte
        szBuf = szBuf & " is not supported by Windows " & "Sockets for 32 bit Windows environments."
        MsgBox szBuf, vbExclamation
        Exit Function
    End If

    '  判断Winsock的版本是否被32为Winsock支持
    If WSAD.wMaxSockets < MIN_SOCKETS_REQD Then
        szBuf = "This application requires a minimum of " & Trim$(Str$(MIN_SOCKETS_REQD)) & " supported sockets."
        MsgBox szBuf, vbExclamation
        Exit Function
    End If
    SocketsInitialize = True
End Function'  关闭Sockets
Private Sub SocketsCleanup()
    Dim X As Long
    '关闭Sockets
    X = WSACleanup()
    If X <> 0 Then
        MsgBox "Windows Sockets error " & Trim$(Str$(X)) & " occurred in Cleanup.", vbExclamation
    End If
End SubPrivate Sub Command1_Click()
    Dim ECHO As ICMP_ECHO_REPLY
    Dim pos As Integer
    If SocketsInitialize() Then
        'ping地址
        Call Ping(Text2.Text, ECHO)
        '显示ping结果
        Text1(0).Text = GetStatusCode(ECHO.status)
        Text1(1).Text = ECHO.RoundTripTime & " ms"
        Text1(2).Text = ECHO.DataSize & " bytes"
        If Left$(ECHO.Data, 1) <> Chr$(0) Then
            pos = InStr(ECHO.Data, Chr$(0))
            Text1(3).Text = Left$(ECHO.Data, pos - 1)
        End If
        Text1(4).Text = ECHO.DataPointer
        SocketsCleanup
    End If
End Sub

不太明白你意思。如果是用户在线，你在用户登录时改变一个字段ture,注销时改成false。

winsock發消息過去，接受就是ok，所以用tcp處理就ok

Option ExplicitPublic Enum NetConnTypeConstants
   INTERNET_CONNECTION_MODEM = &H1&
   INTERNET_CONNECTION_LAN = &H2&
   INTERNET_CONNECTION_PROXY = &H4&
   INTERNET_RAS_INSTALLED = &H10&
   INTERNET_CONNECTION_OFFLINE = &H20&
   INTERNET_CONNECTION_CONFIGURED = &H40&
End Enum
Private Const RAS_MAXENTRYNAME As Integer = 256
Private Const RAS_MAXDEVICETYPE As Integer = 16
Private Const RAS_MAXDEVICENAME As Integer = 128
Private Const RAS_RASCONNSIZE As Integer = 412Private Type RasEntryName
    dwSize As Long
    szEntryName(RAS_MAXENTRYNAME) As Byte
End TypePrivate Type RasConn
    dwSize As Long
    hRasConn As Long
    szEntryName(RAS_MAXENTRYNAME) As Byte
    szDeviceType(RAS_MAXDEVICETYPE) As Byte
    szDeviceName(RAS_MAXDEVICENAME) As Byte
End TypePrivate Declare Function RasEnumConnections Lib _
"rasapi32.dll" Alias "RasEnumConnectionsA" (lpRasConn As _
Any, lpcb As Long, lpcConnections As Long) As LongPrivate Declare Function RasHangUp Lib "rasapi32.dll" Alias _
"RasHangUpA" (ByVal hRasConn As Long) As LongPrivate Declare Function InternetGetConnectedStateEx Lib "wininet.dll" Alias "InternetGetConnectedStateExA" _
(ByRef lpdwFlags As Long, _
ByVal lpszConnectionName As String, _
ByVal dwNameLen As Long, _
ByVal dwReserved As Long _
) As Long
Private Function InternetConnected( _
    Optional ByRef eConnectionInfo As NetConnTypeConstants, _
    Optional ByRef sConnectionName As String _
    ) As Boolean

    Dim dwFlags As Long
    Dim sNameBuf As String
    Dim lR As Long
    Dim iPos As Long

    sNameBuf = String$(513, 0)
    lR = InternetGetConnectedStateEx(dwFlags, sNameBuf, 512, 0&)
    eConnectionInfo = dwFlags
    iPos = InStr(sNameBuf, vbNullChar)

    If iPos > 0 Then
        sConnectionName = Left$(sNameBuf, iPos - 1)
    ElseIf Not sNameBuf = String$(513, 0) Then
        sConnectionName = sNameBuf
    End If

    InternetConnected = (lR = 1)
End Function
Public Property Get IsConnected() As Boolean
    IsConnected = InternetConnected()
End PropertyPublic Property Get ConnType() As Long
    Dim connInfo As NetConnTypeConstants
    InternetConnected connInfo
    ConnType = connInfo
End PropertyPublic Function ConnTypeDevice(nType As Long) As String
    Dim strReturn As String

    If nType And INTERNET_CONNECTION_LAN Then
        strReturn = "LAN"
    ElseIf nType And INTERNET_CONNECTION_MODEM Then
        strReturn = "Modem"
    ElseIf nType And INTERNET_CONNECTION_PROXY Then
        strReturn = "Proxy"
    ElseIf nType And INTERNET_CONNECTION_OFFLINE Then
        strReturn = "Offline"
    End If

    ConnTypeDevice = strReturn
End FunctionPublic Property Get ConnName() As String
    Dim strName As String
    InternetConnected , strName
    ConnName = strName
End PropertyPublic Sub HangUp()
    Dim i As Long
    Dim lpRasConn(255) As RasConn
    Dim lpcb As Long
    Dim lpcConnections As Long
    Dim hRasConn As Long
    Dim ReturnCode As Long
    Dim gstrISPName As String

    lpRasConn(0).dwSize = RAS_RASCONNSIZE
    lpcb = RAS_MAXENTRYNAME * lpRasConn(0).dwSize
    lpcConnections = 0
    ReturnCode = RasEnumConnections(lpRasConn(0), lpcb, _
    lpcConnections)    If ReturnCode = 0 Then
        For i = 0 To lpcConnections - 1
            If Trim(ByteToString(lpRasConn(i).szEntryName)) = Trim(gstrISPName) Then
                hRasConn = lpRasConn(i).hRasConn
                ReturnCode = RasHangUp(ByVal hRasConn)
            End If
        Next i
    End If
End SubPrivate Function ByteToString(bytString() As Byte) As String
    Dim i As Integer

    i = 0
    While bytString(i) = 0&
        ByteToString = ByteToString & ChrB$(bytString(i))
        i = i + 1
    Wend
End Function以上代码放入一个类模块里，调用。

要简单?这个,最简单'Example Name:IsConnected
'Example by Vijay Phulwadhawa ([email protected])Private Declare Function InternetGetConnectedState Lib "wininet.dll" (ByRef lpdwFlags As Long, ByVal dwReserved As Long) As Long
Private Sub Form_Load()
    MsgBox "Is connected to the internet: " + CStr(IsConnected)
End Sub
Public Function IsConnected() As Boolean
    If InternetGetConnectedState(0&, 0&) = 1 Then
        IsConnected = True
    Else
        IsConnected = False
    End If
End Function

调试易

VB中怎样检测是否在线，越简单越好

解决方案 »