判断当前是否连接到网上

[fushijunnan]

Dim eR As EIGCInternetConnectionState
Dim sMsg As String
Dim sName As String
Dim bConnected as Boolean
Private 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 Enum EIGCInternetConnectionState
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 Function InternetConnected(Optional ByRef eConnectionInfo _
As EIGCInternetConnectionState, Optional ByRef _
sConnectionName As String) As Boolean '判断是否连接到internet子程序

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

bConnected = InternetConnected(eR, sName)

我是通过内部网连到Internet上的，但我无论是把网线插上还是拔下来，bConnected的值都为真，为啥呢？

[cso]

Form1:
Private Sub Command1_Click()

Dim eR As EIGCInternetConnectionState
Dim sMsg As String
Dim sName As String
Dim bConnected As Boolean

' Determine whether we have a connection:
bConnected = InternetConnected(eR, sName)

' The connection state info parameter provides details
' about how we connect:
If (eR And INTERNET_CONNECTION_MODEM) = INTERNET_CONNECTION_MODEM Then
sMsg = sMsg & "使用Modem连接到Internet！" & vbCrLf
End If
If (eR And INTERNET_CONNECTION_LAN) = INTERNET_CONNECTION_LAN Then
sMsg = sMsg & "使用内部网连接到Internet！" & vbCrLf
End If
If (eR And INTERNET_CONNECTION_PROXY) = INTERNET_CONNECTION_PROXY Then
sMsg = sMsg & "通过代理服务器连接到Internet！" & vbCrLf
End If
If (eR And INTERNET_CONNECTION_OFFLINE) = INTERNET_CONNECTION_OFFLINE Then
sMsg = sMsg & "现在连接处于离县状态！" & vbCrLf
End If
If (eR And INTERNET_CONNECTION_CONFIGURED) = INTERNET_CONNECTION_CONFIGURED Then
sMsg = sMsg & "连接已经被设定！" & vbCrLf
Else
sMsg = sMsg & "没有设定好的连接！" & vbCrLf
End If
If (eR And INTERNET_RAS_INSTALLED) = INTERNET_RAS_INSTALLED Then
sMsg = sMsg & "本机已经安装了远程访问服务功能！" & vbCrLf
End If

' Display the connection name and info:
If bConnected Then
MsgBox "已连接到Internet,连接名称： " & sName & vbCrLf & sMsg, vbInformation + vbOKOnly, "提示"
Else
MsgBox "没有连接到Internet,连接名称： " & sName & vbCrLf & sMsg, vbCritical + vbOKOnly, "提示"
End If

End Sub


Bas:
'获取网络连接状态
Public 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

Public Enum EIGCInternetConnectionState
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

Public Property Get InternetConnected( _
Optional ByRef eConnectionInfo As EIGCInternetConnectionState, _
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 Property