Question

首先，我绝对不是网络程序员。我尝试做的是Java服务器和C＃客户端之间非常简单的TCP / IP通信。

Java服务器：

 public void run(){   
try {
       // Open server socket
       _server = new ServerSocket(SERVER_PORT);
       _client = _server.accept();
                System.out.println("ComInterface: client connected.");
                // Wait for a client data output stream
                while(true){

                    // Receive message from client
                    BufferedReader is =
                            new BufferedReader(new InputStreamReader(_client.getInputStream()));
                    msg = is.readLine();

                    // Process message
                    if(msg!=null){
                        System.out.println("ComInterface: Message Received : <" + msg + ">.");
                        processMessage(msg); // Independant method
                    }
                    else{
                        System.out.println("ComInterface: client closed connection.");
                        _client.close();
                        _client = _server.accept();
                        System.out.println("ComInterface: client connected.");
                    }

                }

            } catch (IOException e) {
                e.printStackTrace();
            }
}

public void sendMessage(String msg){
        try {

            // Out stream
            DataOutputStream os = new DataOutputStream(_client.getOutputStream());

            os.writeBytes((String)(msg+"\n"+(char)13));
            os.flush();
            System.out.println("ComInterface: Message <" + msg + "> sent");

        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }   
    }

这是C＃客户端：

public class ComInterface : MonoBehaviour
    {
        public const String SERVER_IP = "127.0.0.1"; // Localhost
        public const int PORT = 1100; // Default port 
        public const int READ_BUFFER_SIZE = 5000; // 4.8828125 kilobytes

        private TcpClient _client;
        private ASCIIEncoding _asen;
        private byte[] _readBuffer;
        private String _msg;

        public Boolean connected { get; internal set; } // setter is for internal use only

        /**
         * Initialize internal variables (buffer, socket...)
         */
        public ComInterface()
        {
            connected = false;
            _client = new TcpClient();
            _asen = new ASCIIEncoding();
            _readBuffer = new Byte[READ_BUFFER_SIZE];
            _msg = String.Empty;
        }

        /**
         * Connect to server at SERVER_IP:PORT
         * Return true if connection was a success, or false if failure.
         */
        public Boolean Connect()
        {
            try
            {

                _client.Connect(SERVER_IP, PORT);
                connected = true;
                Array.Clear(_readBuffer, 0, _readBuffer.Length);
                Debug.Log("TCPClient: <Connect> Connected to the server");
                // Start an asynchronous read invoking ReceiveComMessage
                _client.GetStream().BeginRead(_readBuffer, 0, READ_BUFFER_SIZE, new AsyncCallback(ReceiveComMessage), _client.GetStream());
            }
            catch (Exception ex)
            {
                Debug.Log("TCPClient: <Connect> Cannot connect to the server - " + ex.Message);
                connected = false;
            }
            // Return connection state
            return connected;
        }

 /**
         * Received a message from Communicator
         */
        private void ReceiveComMessage(IAsyncResult ar)
        {
            int BytesRead;
            String msg;
            try
            {
                BytesRead = _client.GetStream().EndRead(ar);
                if (BytesRead < 1)
                {
                    // if no bytes were read server has close.  
                    Debug.Log("TCPClient: <ReceiveComMessage> The server has closed (BytesRead<1)");
                    this.Disconnect();
                    return;
                }
                // Convert the byte array the message was saved into,
                msg = Encoding.ASCII.GetString(_readBuffer);
                Debug.Log("C# Message: \"" + msg + "\""); // Output example in log below
                BytesRead = 0;
                Array.Clear(_readBuffer, 0, _readBuffer.Length);

                // Start a new asynchronous read into readBuffer.
                _client.GetStream().BeginRead(_readBuffer, 0, READ_BUFFER_SIZE, new AsyncCallback(ReceiveComMessage), _readBuffer);

            }
            catch (Exception ex)
            {
                Debug.Log("TCPClient: <ReceiveComMessage> The server has closed (Exception):" + ex.Message + " see " + ex.StackTrace);
                this.Disconnect();
            }

主要问题是所有消息都到达不完整。这是日志跟踪：

C#: Message "{
C#: Message ""sender":"Bob"",
C#: Message ""recipient":",
etc...

而不是例如

C#: Message "{"sender":"Bob","recipient":[1,2,3]}"

我有点困惑，我需要一些帮助来解决这个问题。非常感谢你！

Answer 1

通过套接字发送的消息（我的意思是任何数据）分为几个数据包。打印每个收到的数据包时，您看不到整条信息。

您应该定义消息的结尾字符串（类似“。＃。”）。在收到此序列之前，您将继续连接收到的邮件。

这就是会话协议（即在TCP顶部运行的协议）。

希望这有帮助。

问候，Calil

Answer 2

TCP是面向流的连接，而不是面向消息的连接。它没有消息的概念。当你写出你的序列化字符串时，它只会看到无意义的字节序列。 TCP可以自由地将该流分解为多个片段，并且将在客户端以这些片段大小的块接收它们。您可以在另一端重建整个消息。

在您的方案中，通常会发送消息长度前缀。这样，客户端首先读取长度前缀，以便随后知道传入消息应该有多大。

我会认真考虑使用Google Protocol Buffers之类的东西作为声明邮件的好方法，然后使用尺寸前缀选项对其进行流式处理。好处是你定义了一组消息，然后使用可用的tools从消息定义中自动生成C ++，Java，C＃等代码。这将有助于在语言之间建立一致的消息集。

Answer 3

看看这个例子......

Java TCP Server ...

import java.net.*;
import java.io.*;

public class TcpServer
{
    public static void main(String h[])
    {
        try
        {
            ServerSocket serverSocket = new ServerSocket(1100);
            Socket socket = serverSocket.accept();
            System.out.println("Client Accepted");
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            System.out.println("Received: " + bufferedReader.readLine());
            PrintWriter printWriter = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()), true);
            printWriter.println("Hello Theo. Welcome to socket programming.");
        } catch (Exception e)
        {
            System.out.println(e);
        }
    }
}

C＃TCP客户端......

using System;
using System.IO;
using System.Net.Sockets;

class Program
{
    static void Main(string[] args)
    {
        try
        {
            var client = new TcpClient("localhost", 1100);
            var stream = client.GetStream();
            var streamWriter = new StreamWriter(stream);
            streamWriter.WriteLine("My name is Theo");
            streamWriter.Flush();
            var streamReader = new StreamReader(stream);
            Console.WriteLine("Received: " + streamReader.ReadLine());
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
        }

        Console.WriteLine("Press a key to continue.");
        Console.ReadKey();
    }
}

不完整的消息（C＃TCP / IP客户端）

3 个答案: