VB怎么檢查網(wǎng)絡(luò)連接狀態(tài)

如果是檢查winsock的連接狀態(tài)可以用，if winsock1.state=*

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sckClosed 0 缺省的。關(guān)閉

sckOpen 1 打開

sckListening 2 偵聽

sckConnectionPending 3 連接掛起

sckResolvingHost 4 識(shí)別主機(jī)

sckHostResolved 5 已識(shí)別主機(jī)

sckConnecting 6 正在連接

sckConnected 7 已連接

sckClosing 8 同級(jí)人員正在關(guān)閉連接

sckError 9 錯(cuò)誤

*值得就是上述值的一個(gè)，然后在后面添加代碼！例如要判斷時(shí)候關(guān)閉，就可以

if winsock1.state=0 then msgbox "未連接!"

這樣的沒有連接就會(huì)彈出對(duì)話框了

VB如何調(diào)用ping命令來判斷是否聯(lián)網(wǎng)!?

首先添加一模塊，代碼如下

Option Explicit

Private Const IP_SUCCESS As Long = 0

Private Const IP_STATUS_BASE As Long = 11000

Private Const IP_BUF_TOO_SMALL As Long = (11000 + 1)

Private Const IP_DEST_NET_UNREACHABLE As Long = (11000 + 2)

Private Const IP_DEST_HOST_UNREACHABLE As Long = (11000 + 3)

Private Const IP_DEST_PROT_UNREACHABLE As Long = (11000 + 4)

Private Const IP_DEST_PORT_UNREACHABLE As Long = (11000 + 5)

Private Const IP_NO_RESOURCES As Long = (11000 + 6)

Private Const IP_BAD_OPTION As Long = (11000 + 7)

Private Const IP_HW_ERROR As Long = (11000 + 8)

Private Const IP_PACKET_TOO_BIG As Long = (11000 + 9)

Private Const IP_REQ_TIMED_OUT As Long = (11000 + 10)

Private Const IP_BAD_REQ As Long = (11000 + 11)

Private Const IP_BAD_ROUTE As Long = (11000 + 12)

Private Const IP_TTL_EXPIRED_TRANSIT As Long = (11000 + 13)

Private Const IP_TTL_EXPIRED_REASSEM As Long = (11000 + 14)

Private Const IP_PARAM_PROBLEM As Long = (11000 + 15)

Private Const IP_SOURCE_QUENCH As Long = (11000 + 16)

Private Const IP_OPTION_TOO_BIG As Long = (11000 + 17)

Private Const IP_BAD_DESTINATION As Long = (11000 + 18)

Private Const IP_ADDR_DELETED As Long = (11000 + 19)

Private Const IP_SPEC_MTU_CHANGE As Long = (11000 + 20)

Private Const IP_MTU_CHANGE As Long = (11000 + 21)

Private Const IP_UNLOAD As Long = (11000 + 22)

Private Const IP_ADDR_ADDED As Long = (11000 + 23)

Private Const IP_GENERAL_FAILURE As Long = (11000 + 50)

Private Const MAX_IP_STATUS As Long = (11000 + 50)

Private Const IP_PENDING As Long = (11000 + 255)

Private Const PING_TIMEOUT As Long = 500

Private Const WS_VERSION_REQD As Long = H101

Private Const MIN_SOCKETS_REQD As Long = 1

Private Const SOCKET_ERROR As Long = -1

Private Const INADDR_NONE As Long = HFFFFFFFF

Private Const MAX_WSADescription As Long = 256

Private Const MAX_WSASYSStatus As Long = 128

Public PingTime As Long

Private Type ICMP_OPTIONS

Ttl As Byte

Tos As Byte

Flags As Byte

OptionsSize As Byte

OptionsData As Long

End Type

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

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 Type

Public Declare Function timeGetTime Lib "winmm.dll" () As Long

Private Declare Function WSAStartup Lib "wsock32" (ByVal wVersionRequired As Long, lpWSADATA As WSADATA) As Long

Private Declare Function WSACleanup Lib "wsock32" () As Long

Private Declare Function IcmpCreateFile Lib "icmp.dll" () As Long

Private Declare Function inet_addr Lib "wsock32" (ByVal s As String) 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" () As Long

'Private Declare Function gethostname Lib "wsock32" (ByVal szHost As String, ByVal dwHostLen As Long) As Long

'Private Declare Function gethostbyname Lib "wsock32" (ByVal szHost As String) As Long

'Private Declare Sub CopyMemory Lib "kernel32" Alias "RtlMoveMemory" (xDest As Any, xSource As Any, ByVal nbytes As Long)

Private Function GetStatusCode(status As Long) As String

On Error GoTo ErrLine

Dim Msg As String

GetStatusCode = ""

Select Case status

Case IP_SUCCESS: Msg = "ip success"

Case INADDR_NONE: Msg = "inet_addr: bad IP format"

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 port 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 = Msg

Exit Function

ErrLine:

End Function

Private Function Ping(sAddress As String, sDataToSend As String, ECHO As ICMP_ECHO_REPLY) As Long

On Error GoTo ErrLine

Dim hPort As Long

Dim dwAddress As Long

dwAddress = inet_addr(sAddress)

If dwAddress INADDR_NONE Then

hPort = IcmpCreateFile()

If hPort Then

Call IcmpSendEcho(hPort, dwAddress, sDataToSend, Len(sDataToSend), 0, ECHO, Len(ECHO), PING_TIMEOUT)

Ping = ECHO.status

Call IcmpCloseHandle(hPort)

End If

Else

Ping = INADDR_NONE

End If

Exit Function

ErrLine:

Ping = INADDR_NONE

End Function

Public Function PingIP(ByVal szIp As String) As Boolean

On Error GoTo ErrLine

Dim WSAD As WSADATA

Dim ECHO As ICMP_ECHO_REPLY

Dim ret As Long

'Delay 150

PingIP = False

PingTime = Empty

If WSAStartup(WS_VERSION_REQD, WSAD) = IP_SUCCESS Then

ret = Ping(Trim(szIp), "tanaya", ECHO)

PingTime = ECHO.RoundTripTime

If InStr(1, GetStatusCode(ret), "success") 0 Then

WSACleanup

PingIP = True

PingTime = ECHO.RoundTripTime

Exit Function

End If

End If

Exit Function

ErrLine:

End Function

然后建立一窗體，一command

Private Sub Command1_Click()

If PingIP("你需要訪問的ip") = True Then

'你自己增加需要執(zhí)行的代碼

else

'增加不聯(lián)網(wǎng)時(shí)需要執(zhí)行的代碼

end if

vb.net 如何判斷網(wǎng)絡(luò)地址上的指定文件是否存在

Private Declare Function PathFileExists Lib "shlwapi.dll" Alias "PathFileExistsA" (ByVal pszPath As String) As Long

這是封裝在Shell32.DLL系統(tǒng)文件里的一個(gè)函數(shù)，既可以判斷本地文件是否存在，又可以判斷遠(yuǎn)程電腦上的文件是否存在。函數(shù)返回值是個(gè)Long型變量，返回兩個(gè)值0,1。1表示文件存在(True),0表示文件不存在(False)。而且只有一個(gè)參數(shù)szPath,是個(gè)字符串變量，如果要判斷本地的文件是否存在其路徑可寫為：”C:\Windows\Config\SysBook.Txt”)，如果文件在遠(yuǎn)程電腦上，其路徑可寫為（假設(shè)對(duì)方電腦IP為192.168.0.2)

"\\192.168.0.2\d$\javatools\somefile.txt",如果其電腦名為WorkStation可寫為

“\\workstation\javatools\somefile.txt"，當(dāng)然這個(gè)函數(shù)還可以查找網(wǎng)站上的網(wǎng)頁文件如：""

我們可以寫個(gè)簡單的自定義公用函數(shù)來完成這個(gè)功能，在自定義函數(shù)里調(diào)用這個(gè)API函數(shù)

Public Function GetFileExists(ByVal FileName As String) As Boolean

If FileName = "" Then

MsgBox "請(qǐng)輸入文件名", vbInformation, "提示"

Exit Function

Else

GetFileExists = CBool(PathFileExists(FileName))

End If

End Function

在窗體界面上加一按鈕,和一文本框

Private Sub Command1_Click()

Dim T As Boolean

T = GetFileExists("F:\it\Develope\Retail\Bill\vssver.scc")

If T = True Then

Text1.Text = "該文件存在"

Else

Text1.Text = "該文件不存在"

End If

End Sub

當(dāng)然GetFileExists其中的參數(shù)還可以寫成

"\\192.168.0.2\d$\javatools\somefile.txt"

"\\workstation\javatools\somefile.txt"

""

這個(gè)函數(shù)除了能判斷文件是否存在外，還可以判斷本地或遠(yuǎn)程文件夾

是否存在，我覺得這要比用Dir這個(gè)VB自帶函數(shù)來判斷文件是否存在要好用多了，而且也不需要調(diào)用FileSystemObject組件來操作了。

vb.net測試數(shù)據(jù)庫是否能連接

serverstring = "Server=" 服務(wù)器IP ";DataBase=" 庫名 ";Userid=" 用戶名 ";Password=" 密碼

Try

Conn = New MySqlConnection(serverstring)

Conn.Open()

MsgBox("連接成功")

Conn.Dispose()

Conn.Close()

Catch ex As Exception

MsgBox("連接失敗！")

End Try

這是 mysql 的，自己改成 sql server 的就行了

VB.NET如何判斷電腦是否已連接到網(wǎng)絡(luò)？

Microsoft.VisualBasic.Devices.Network.IsAvailable As Boolean

生成實(shí)例后可以通過此屬性來獲取是否聯(lián)網(wǎng)的值，True代表已聯(lián)網(wǎng)，F(xiàn)alse代表沒有聯(lián)網(wǎng)

Microsoft.VisualBasic.Devices.Network.NetworkAvailabilityChanged(ByVal Object, ByVal Microsoft.VisualBasic.Devices.NetworkAvailableEventArgs)

該事件是在電腦斷開/連上互聯(lián)網(wǎng)是引發(fā)的

其中：

e.IsNetworkAvailable

的功能同Microsoft.VisualBasic.Devices.Network.IsAvailable

實(shí)例:

Dim?netListener?As?New?Microsoft.VisualBasic.Devices.Network?'生成實(shí)例

If?netListener.IsAvailable?=?True?Then

MsgBox("已聯(lián)網(wǎng)")

Else

MsgBox("未聯(lián)網(wǎng)")

End?If

NetworkAvailabilityChanged實(shí)例：

WithEvents?netListener?As?New?Microsoft.VisualBasic.Devices.Network?'生成實(shí)例

Private?Sub?OnNetworkChanged(ByVal?Object,?ByVal?Microsoft.VisualBasic.Devices.NetworkAvailableEventArgs)Handles?netListener.NetworkAvailabilityChanged

If?e.IsNetworkAvailable?=?True?Then

MsgBox("已聯(lián)網(wǎng)")

Else

MsgBox("未聯(lián)網(wǎng)")

End?If

End?Sub

求大神指點(diǎn)vb.net 怎么判斷 網(wǎng)絡(luò)是否連接 和取本機(jī)局域網(wǎng)IP和互聯(lián)網(wǎng)IP

你這段代碼可以獲得該主機(jī)名下的所有ip，每個(gè)ip地址都是有類型簇的，可以區(qū)別本地地址和網(wǎng)絡(luò)地址、ip6地址。

你獲取索引為0的ip，不一定是正確的網(wǎng)絡(luò)地址，它有時(shí)順序在中間，在后面。

應(yīng)該獲取所有ip，再通過ip地址簇類型區(qū)分

判斷連接本身有一個(gè)函數(shù)，不過有時(shí)沒聯(lián)網(wǎng)也是真。

可以用ping，ping百度、ping訪問速度快、不經(jīng)常維護(hù)斷線的網(wǎng)絡(luò)主機(jī)。