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求大神指點vb點虐 怎么判斷 網(wǎng)絡(luò)是否連接 和取本機局域網(wǎng)IP和互聯(lián)網(wǎng)IP
你這段代碼可以獲得該主機名下的所有ip,每個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。
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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函數(shù),不過有時沒聯(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。
VB與VB.NET串口及以太網(wǎng)通迅
關(guān)于串口通訊的問題:
很明顯,你還不知道(不會、不習(xí)慣)使用事件驅(qū)動的方式接收數(shù)據(jù)。
建議你仔細(xì)看看串口組件(無論VB6還是VB點虐 )的OnComm事件,你的問題很容易解決。
關(guān)于以太網(wǎng)通訊:
在TCP通訊中端口確實可以重用,你百度一下“TCP端口重用”能查到很多示例。
但絕大多數(shù)情況下不推薦端口重用,而應(yīng)該采取服務(wù)器端建立連接池的方法。
或者,干脆不用TCP,用UDP解決也可以。
用vb點虐 實現(xiàn)網(wǎng)絡(luò)通信
用 vb點虐 socket通信
Dim th As Threading.Thread
2 Dim tcpl As System.Net.Sockets.TcpListener
3
4 Private Sub Form1_Load()Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
5 th = New System.Threading.Thread(New System.Threading.ThreadStart(AddressOf MyListen))
6 th.Start()
7 End Sub
8
9 Public Sub SendMessage()Sub SendMessage(ByVal IP As String, ByVal SendMsg As String)
10 Try
11 If IP "" Then
12 Dim tcpc As New System.Net.Sockets.TcpClient(IP, 5656)
13 Dim tcpStream As Net.Sockets.NetworkStream = tcpc.GetStream
14 Dim reqStream As New IO.StreamWriter(tcpStream)
15 reqStream.Write(SendMsg)
16 reqStream.Flush()
17 tcpStream.Close()
18 tcpc.Close()
19 End If
20 Catch ex As Exception
21 MsgBox(ex.Message.ToString)
22 End Try
23 End Sub
24 Private Sub MyListen()Sub MyListen()
25 Try
26 Dim ipAddress As System.Net.IPAddress = System.Net.Dns.Resolve(System.Net.Dns.GetHostName).AddressList(0)
27 tcpl = New System.Net.Sockets.TcpListener(ipAddress, 5656)
28 tcpl.Start()
29 While True
30 Dim s As System.Net.Sockets.Socket = tcpl.AcceptSocket()
31 Dim MyBuffer(1024) As Byte
32 Dim i As Integer
33 i = s.Receive(MyBuffer)
34 If i 0 Then
35 Dim lstrRec As String
36 Dim j As Integer
37 For j = 0 To i - 1
38 TextBox1.Text += Chr(MyBuffer(j)) ","
39 Next
40 End If
41 End While
42 Catch ex As Exception
43 MsgBox(ex.Message.ToString)
44 End Try
45 End Sub
46
47 Private Sub Button1_Click()Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
48 SendMessage("192.168.0.61", TextBox2.Text)
49 End Sub
網(wǎng)頁標(biāo)題:vb點虐 網(wǎng)線 vb net
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