VB.NET經過長時間的發(fā)展，很多用戶都很了解VB.NET Socket編程了，這里我發(fā)表一下個人理解，和大家討論討論。一直以來很想學習VB.NET Socket編程方面的應用，比如怎樣通過VB.NET Socket編程實現(xiàn)單片機與PC的TCP連接通信。在單片機嵌入網卡芯片與PC進行連接通信，實現(xiàn)PC的web方式對單片機所控制的設備的狀態(tài)管理，例如智能家居方面的應用。

下面通過例子來學習VB.NET Socket編程類的應用，下面的程序分別分服務器和客戶端兩部分：

ImportsSystem  
ImportsSystem.Net  
ImportsSystem.Net.Sockets  
ImportsSystem.Text  
ImportsSystem.Threading  
ImportsMicrosoft.VisualBasic  
 
'Stateobjectforreadingclientdataasynchronously  
 
PublicClassStateObject  
'Clientsocket.  
PublicworkSocketAsSocket=Nothing 
'Sizeofreceivebuffer.  
PublicConstBufferSizeAsInteger=1024 
'Receivebuffer.  
Publicbuffer(BufferSize)AsByte  
'Receiveddatastring.  
PublicsbAsNewStringBuilder  
EndClass'StateObject  
 
 
PublicClassAsynchronousSocketListener  
'Threadsignal.  
PublicSharedallDoneAsNewManualResetEvent(False)  
 
'Thisserverwaitsforaconnectionandthenusesasychronousoperationsto  
'accepttheconnection,getdatafromtheconnectedclient,  
'echothatdatabacktotheconnectedclient.  
'Itthendisconnectsfromtheclientandwaitsforanotherclient.  
PublicSharedSubMain()  
'Databufferforincomingdata.  
Dimbytes()AsByte=New[Byte](1023){}  
 
'Establishthelocalendpointforthesocket.  
DimipHostInfoAsIPHostEntry=Dns.Resolve(Dns.GetHostName())  
DimipAddressAsIPAddress=ipHostInfo.AddressList(0)  
DimlocalEndPointAsNewIPEndPoint(ipAddress,11000)  
 
'CreateaTCP/IPsocket.  
DimlistenerAsNewSocket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp)  
 
'Bindthesockettothelocalendpointandlistenforincomingconnections.  
listener.Bind(localEndPoint)  
listener.Listen(100)  
 
WhileTrue  
'Settheeventtononsignaledstate.  
allDone.Reset()  
 
'Startanasynchronoussockettolistenforconnections.  
Console.WriteLine("Waitingforaconnection...")  
listener.BeginAccept(NewAsyncCallback(AddressOfAcceptCallback),listener)  
 
'Waituntilaconnectionismadeandprocessedbeforecontinuing.  
allDone.WaitOne()  
EndWhile  
EndSub'Main  
 
 
PublicSharedSubAcceptCallback(ByValarAsIAsyncResult)  
'Getthesocketthathandlestheclientrequest.  
DimlistenerAsSocket=CType(ar.AsyncState,Socket)  
'Endtheoperation.  
DimhandlerAsSocket=listener.EndAccept(ar)  
 
'Createthestateobjectfortheasyncreceive.  
DimstateAsNewStateObject  
state.workSocket=handler 
handler.BeginReceive(state.buffer,0,StateObject.
BufferSize,0,NewAsyncCallback(AddressOfReadCallback),state)  
EndSub'AcceptCallback  
 
 
PublicSharedSubReadCallback(ByValarAsIAsyncResult)  
DimcontentAsString=String.Empty  
 
'Retrievethestateobjectandthehandlersocket  
'fromtheasynchronousstateobject.  
DimstateAsStateObject=CType(ar.AsyncState,StateObject)  
DimhandlerAsSocket=state.workSocket  
 
'Readdatafromtheclientsocket.  
DimbytesReadAsInteger=handler.EndReceive(ar)  
 
IfbytesRead>0Then  
'Theremightbemoredata,sostorethedatareceivedsofar.  
state.sb.Append(Encoding.ASCII.GetString(state.buffer,0,bytesRead))  
 
'Checkforend-of-filetag.Ifitisnotthere,read  
'moredata.  
content=state.sb.ToString()  
Ifcontent.IndexOf("<EOF>")>-1Then  
'Allthedatahasbeenreadfromthe  
'client.Displayitontheconsole.  
Console.WriteLine("Read{0}bytesfromsocket."+vbLf+"Data:{1}",content.Length,content)  
'Echothedatabacktotheclient.  
Send(handler,content)  
Else  
'Notalldatareceived.Getmore.  
handler.BeginReceive(state.buffer,0,StateObject.
BufferSize,0,NewAsyncCallback(AddressOfReadCallback),state)  
EndIf  
EndIf  
EndSub'ReadCallback  
 
PrivateSharedSubSend(ByValhandlerAsSocket,ByValdataAsString)  
'ConvertthestringdatatobytedatausingASCIIencoding.  
DimbyteDataAsByte()=Encoding.ASCII.GetBytes(data)  
 
'Beginsendingthedatatotheremotedevice.  
handler.BeginSend(byteData,0,byteData.
Length,0,NewAsyncCallback(AddressOfSendCallback),handler)  
EndSub'Send  
 
PrivateSharedSubSendCallback(ByValarAsIAsyncResult)  
'Retrievethesocketfromthestateobject.  
DimhandlerAsSocket=CType(ar.AsyncState,Socket)  
 
'Completesendingthedatatotheremotedevice.  
DimbytesSentAsInteger=handler.EndSend(ar)  
Console.WriteLine("Sent{0}bytestoclient.",bytesSent)  
 
handler.Shutdown(SocketShutdown.Both)  
handler.Close()  
'Signalthemainthreadtocontinue.  
allDone.Set()  
EndSub'SendCallback  
EndClass'AsynchronousSocketListener 

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