通过TCP发送大字符串时丢失数据。 （客户端服务器）

Question

I have a Client/ server application where the Server is in java and Client is in Vb.net.

When i send large string from client to server am not receiving complete text. please help.

code attached below.

client-- VB.net-

      Try
         Dim clientSocket As New System.Net.Sockets.TcpClient()

        ' msg("Client Started")
        clientSocket.Connect(StrIP_Add, intPort)
        clientSocket.SendBufferSize=104857600
        '6511 6522
        ' Label1.Text = "Client Socket Program - Server Connected ..."

        Dim serverStream As NetworkStream = clientSocket.GetStream()
        Dim outStream(104857600) As Byte

        ' MsgBox(strValidator.Trim.Length)

        outStream = System.Text.Encoding.ASCII.GetBytes(strValidator.Trim)
        ' Dim outStream As Byte() = "sdsfd"
        System.Threading.Thread.Sleep(2000)
        serverStream.Write(outStream, 0, outStream.Length)
        System.Threading.Thread.Sleep(2000)
        serverStream.Flush()

        Dim inStream(104857600) As Byte
        serverStream.Read(inStream, 0, outStream.Length) '104857600) ' CInt(clientSocket.ReceiveBufferSize))
        Dim returndata As String = _
        System.Text.Encoding.ASCII.GetString(inStream)
        '  msg("Data from Server : " + returndata)
        clientSocket.Close()

    Catch ex As Exception
        ' VikUcMsg.AddMessage("<b><u>" & Page.Title & "</u></b><br><br>" & "No Connectivity on the port :" & intPort, enmMessageType.Error)


    End Try

---

server-- Java

BufferedInputStream RecievedBuffer = new BufferedInputStream(
                TCPIP_Client_SOCKET.getInputStream());
        InputStreamReader RecievedInputStreamReader = new InputStreamReader(
                RecievedBuffer);

        System.out.println(RecievedBuffer.toString().length());
        //char[] RecievedChars = new char[TCPIP_Client_SOCKET
                //.getReceiveBufferSize()];

        char[] RecievedChars = new char[100000];
        //Thread.sleep(5000);
        RecievedInputStreamReader.read(RecievedChars);
        //Thread.sleep(5000);
        String strRecievedData=null;
        //Thread.sleep(5000);
        strRecievedData = new String( RecievedChars ).trim();
        //strRecievedData = RecievedChars.;
        Thread.sleep(5000);
        if (strRecievedData!=null)
        {
            System.out.println(strRecievedData);
                         }

strRecievedData is only havig 8192 all the time.

Answer 1

Well the short answer is that you must loop when reading from a socket because there is no guarantee how many bytes you will receive on each attempt to read.

Psuedo-code:

while (!msgCompleted && !overallTimeout)
{
   bytesRead = netstream.Read(readBuffer);

   if (bytesRead > 0)
   {
      // here append readBuffer to msgBuffer from offset to offset+bytesRead 

      offset += bytesRead // update offset so you can keep appending

     // inspect the msgBuffer to see if the message is completed
   }

}

That all being said, you've got nyumerous other problems in your code. For example...

You allocate a 104857601 (not 104857600) byte buffer here:

Dim outStream(104857600) As Byte

And then discard and replace that buffer with whatever contents get reurned from strValidator:

outStream = System.Text.Encoding.ASCII.GetBytes(strValidator.Trim)

No point in pre-allocating it just to replace it.

Another one...

You allocate an input buffer of a certain length:

Dim inStream(104857600) As Byte

But then read into that buffer using the length of a different buffer:

serverStream.Read(inStream, 0, outStream.Length)

This is prone to errors depending on the lengths.

You will also need to loop in this VB read just as for the Java read.