Question

用 VB 检测 是否连接网络，

就是，单击command1 显示是否连接
高手给个答案吧，
可以的话，说明下，
答得好加 20-50

Answer 1

'*************************windows xp+sp3,vb6.0 编译通过
Option Explicit
'拨号/断网
Private Declare Function InternetDial Lib "wininet.dll" (ByVal hwndParent As Long, ByVal lpszConnectoid As String, ByVal dwFlags As Long, lpdwConnection As Long, ByVal dwReserved As Long) As Long
Private Declare Function InternetHangUp Lib "wininet.dll" (ByVal dwConnection As Long, ByVal dwReserved As Long) As Long
Private Declare Function InternetAutodial Lib "wininet.dll" (ByVal dwFlags As Long, ByVal dwReserved As Long) As Long
Private Declare Function InternetAutodialHangup Lib "wininet.dll" (ByVal dwReserved As Long) As Long
Private Const INTERNET_DIALSTATE_DISCONNECTED = 1
Private Const INTERNET_AUTODIAL_FORCE_ONLINE = 1
Private Const INTERNET_AUTODIAL_FORCE_UNATTENDED = 2
Private Const INTERNET_DIAL_UNATTENDED = &H8000
Private Handle As Long

'网络状态
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 Declare Function InternetGetConnectedState Lib "wininet.dll" (ByRef dwFlags As Long, ByVal dwReserved As Long) As Long
Private Const INTERNET_CONNECTION_MODEM As Long = &H1 '本系统使用调制解调器与因特网相连
Private Const INTERNET_CONNECTION_LAN As Long = &H2 '本系统通过LAN与因特网相连
Private Const INTERNET_CONNECTION_PROXY As Long = &H4 '本系统使用proxy代理服务器与因特网相连
Private Const INTERNET_CONNECTION_MODEM_BUSY As Long = &H8 '未使用
Private Const INTERNET_RAS_INSTALLED As Long = &H10
Private Const INTERNET_CONNECTION_OFFLINE As Long = &H20
Private Const INTERNET_CONNECTION_CONFIGURED As Long = &H40

'枚举网络连接
Private Const RAS_MaxDeviceType = 16
Private Const RAS95_MaxDeviceName = 128
Private Const RAS95_MaxEntryName = 256
Private Type RASCONN95
dwSize As Long
hRasConn As Long
szEntryName(RAS95_MaxEntryName) As Byte
szDeviceType(RAS_MaxDeviceType) As Byte
szDeviceName(RAS95_MaxDeviceName) As Byte
End Type
Private Type RASENTRYNAME95
dwSize As Long
szEntryName(RAS95_MaxEntryName) As Byte
End Type
Private Declare Function RasEnumConnections Lib "rasapi32.dll" Alias "RasEnumConnectionsA" (lprasconn As Any, lpcb As Long, lpcConnections As Long) As Long
Private Declare Function RasEnumEntries Lib "rasapi32.dll" Alias "RasEnumEntriesA" (ByVal reserved As String, ByVal lpszPhonebook As String, lprasentryname As Any, lpcb As Long, lpcEntries As Long) As Long
Private Declare Function RasHangUp Lib "rasapi32.dll" Alias "RasHangUpA" (ByVal hRasConn As Long) As Long

'拨号
Public Function DialUp(LinkName As String) As Boolean
InternetDial 0, LinkName, INTERNET_AUTODIAL_FORCE_UNATTENDED, Handle, 0
DialUp = (Handle <> 0)
End Function
'断网
Public Sub HangUp()
If Handle <> 0 Then
InternetHangUp Handle, 0
Handle = 0
End If
End Sub
'枚举网络连接
Public Sub EnumConnectName(Value() As String)
Dim s As Long, l As Long, ln As Long, a As String
ReDim r(255) As RASENTRYNAME95

r(0).dwSize = 264
s = 256 * r(0).dwSize
l = RasEnumEntries(vbNullString, vbNullString, r(0), s, ln)
ReDim Value(ln - 1)
For l = 0 To ln - 1
a = StrConv(r(l).szEntryName(), vbUnicode)
Value(l) = Left$(a$, InStr(a$, Chr$(0)) - 1)
Next
End Sub

'判断是否在线
Public Function Online() As Boolean
Online = InternetGetConnectedState(0&, 0&)
End Function
'判断是否在线并返回连接方式
Public Property Get OnlineOfLinkName(LinkName As String) As Boolean
LinkName = Space$(128)
OnlineOfLinkName = InternetGetConnectedStateEx(0, LinkName, 128, 0&)
End Property

'如果是通过LAN的连接，则返回True
Public Function IsNetConnectViaLAN() As Boolean
Dim dwFlags As Long
Call InternetGetConnectedState(dwFlags, 0&)
IsNetConnectViaLAN = dwFlags And INTERNET_CONNECTION_LAN
End Function

'如果是通过调制解调器的连接，则返回True
Public Function IsNetConnectViaModem() As Boolean
Dim dwFlags As Long
Call InternetGetConnectedState(dwFlags, 0&)
IsNetConnectViaModem = dwFlags And INTERNET_CONNECTION_MODEM
End Function

'如果是通过Proxy代理服务器的连接，则返回True
Public Function IsNetConnectViaProxy() As Boolean
Dim dwFlags As Long
Call InternetGetConnectedState(dwFlags, 0&)
IsNetConnectViaProxy = dwFlags And INTERNET_CONNECTION_PROXY
End Function

'如果已安装了RAS，则返回True
Public Function IsNetRASInstalled() As Boolean
Dim dwFlags As Long
Call InternetGetConnectedState(dwFlags, 0&)
IsNetRASInstalled = dwFlags And INTERNET_RAS_INSTALLED
End Function
'返回当前网络状态信息字符串
Public Function GetNetConnectString() As Boolean

Dim dwFlags As Long
Dim Msg As String
If InternetGetConnectedState(dwFlags, 0&) Then
If dwFlags And INTERNET_CONNECTION_CONFIGURED Then
Msg = MsgBox("系统配置了网络连接") & vbCrLf
End If
If dwFlags And INTERNET_CONNECTION_LAN Then
Msg = MsgBox("系统通过局域网与因特网相连接")
End If
If dwFlags And INTERNET_CONNECTION_PROXY Then
Msg = MsgBox("并使用了Proxy代理服务")

End If
If dwFlags And INTERNET_CONNECTION_MODEM Then
Msg = MsgBox("系统使用调制解调器与因特网相连接")
End If
If dwFlags And INTERNET_CONNECTION_OFFLINE Then
Msg = MsgBox("系统当前处于离线状态")
End If
If dwFlags And INTERNET_CONNECTION_MODEM_BUSY Then
Msg = MsgBox("系统的调制解调器未连接到因特网")
End If
If dwFlags And INTERNET_RAS_INSTALLED Then
Msg = MsgBox("本系统安装了远程访问服务")
End If
GetNetConnectString = True
Else
Msg = MsgBox("当前未与因特网相连")
GetNetConnectString = False
End If

End Function

Private Sub Command1_Click()
GetNetConnectString
End Sub

追问

还是有问题， 我这是通过软件上网的，我断开后，我试了一试，还是显示连接

追答

为什么你的网络连接符号是“！”而不是红”X“。

追问

⊙﹏⊙b汗，你这代码哪来的？？？？我很怀疑，你学电脑？？？？

Answer 2

'你需要添加一个Webbrowser空间,时间空间timer1 及label1,当然可以更改为 text1

Private Sub Form_Load()
Label1.Caption = "连接状态： 正在初始化连接 " & Now()
WebBrowser1.Navigate ("")
Timer1.Interval = 2000
End Sub

Private Sub Timer1_Timer()
If WebBrowser1.Busy = False Then

If InStr(WebBrowser1.Document.body.innerText, "百度") > 0 Then

Label1.Caption = "连接状态：当前已连接到互联网" & Now()
Else
Label1.Caption = "连接状态： 当前已断开 " & Now()

End If

WebBrowser1.Refresh

End If

End Sub
'原理就是每隔2秒检测能否连接到来判断是否连接互联网

Answer 3

最简单的方法：
添加部件Windows Media Player

Private Sub Command1_Click()
MsgBox WindowsMediaPlayer1.isOnline
End Sub

WindowsMediaPlayer1.isOnline 返回值真/假。。。

追问

不行的，跟我其他网上查的一样，

追答

我试过可以啊，你断网后，稍微等一会再运行程序，再试，就会得到" False "，见图

追问

不，不是的，我的使用软件上网的，你的方法，不可靠

追答

你可以用VB 来Ping www.baidu.com，通了就是联网，参考：
http://zhidao.baidu.com/question/179336025.html
http://zhidao.baidu.com/question/208817860.html