解决Java客户端与C#服务器TCP通信无响应问题：消息帧与资源管理指南

public void CreateServer()
{
    Thread thread = new Thread(() =>
    {
        IPAddress addr = IPAddress.Parse(localIP);
        tcpListener = new TcpListener(addr, 5053);
        if (tcpListener != null)
        {
            tcpListener.Start();
            while (!end)
            {      
                TcpClient tcpClient = tcpListener.AcceptTcpClient();
                var ip = ((IPEndPoint)tcpClient.Client.RemoteEndPoint).Address.ToString();
                Console.WriteLine("Client connected from "+ip);   
                NetworkStream clientStream = tcpClient.GetStream();
                StreamReader reader = new StreamReader(clientStream, Encoding.UTF8);
                try
                {
                    string request = reader.ReadToEnd(); // 关键点1：ReadToEnd()
                    Console.WriteLine("Message from client: " + request);

                    Byte[] StringToSend = Encoding.UTF8.GetBytes("Server"); // 关键点2：响应无定界符
                    clientStream.Write(StringToSend, 0, StringToSend.Length);
                    Console.WriteLine("Sending response back");
                }
                catch (Exception e)
                {
                    Console.WriteLine(e);
                } 
            }
        }
    });
    thread.Start();
}

public class TCP {
    private String IP;
    private InetAddress server;
    private Socket socket;

    public TCP(String IP) {
        this.IP = IP;
    }

    protected void runTCP() {
        try {
            server = InetAddress.getByName(IP);
            socket = new Socket(server, 5053);
            System.out.println("Client connected. Listening on port 5053");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void sendMessage(String message) {
        try {
            System.out.println("Sending data...");
            if (socket.isClosed()) socket = new Socket(server, 5053); // 关键点3：重复创建Socket
            PrintWriter writer = new PrintWriter(socket.getOutputStream());
            writer.print(message);
            writer.flush();
            writer.close(); // 关键点4：过早关闭PrintWriter
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public void getResponseServer() {
        Thread thread = new Thread() {
            @Override
            public void run() {
                try {
                    System.out.println("Attempting to get response...");
                    if (socket.isClosed()) socket = new Socket(server, 5053); // 关键点3：重复创建Socket
                    BufferedReader mBufferIn = new BufferedReader(new InputStreamReader(socket.getInputStream()));
                    String mServerMessage = mBufferIn.readLine(); // 关键点5：readLine()依赖换行符
                    System.out.println("Server message: " + mServerMessage);
                } catch (Exception e) {e.printStackTrace();}
            }
        };
        thread.start();
    }
}

using System;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Text;
using System.Threading;

public class Server
{
    private TcpListener tcpListener;
    private bool end = false; // 控制服务器循环的标志，实际应用中应有更完善的停止机制
    private string localIP = "127.0.0.1"; // 示例IP，请根据实际情况修改

    public void CreateServer()
    {
        Thread thread = new Thread(() =>
        {
            IPAddress addr = IPAddress.Parse(localIP);
            tcpListener = new TcpListener(addr, 5053);
            try
            {
                tcpListener.Start();
                Console.WriteLine("C# Server started on " + localIP + ":5053");

                while (!end)
                {      
                    TcpClient tcpClient = tcpListener.AcceptTcpClient();
                    var ip = ((IPEndPoint)tcpClient.Client.RemoteEndPoint).Address.ToString();
                    Console.WriteLine("Client connected from " + ip);   

                    NetworkStream clientStream = tcpClient.GetStream();
                    // 使用StreamReader/Writer，但要确保消息定界
                    using (StreamReader reader = new StreamReader(clientStream, Encoding.UTF8, true, 1024, true)) // LeaveOpen = true
                    using (StreamWriter writer = new StreamWriter(clientStream, Encoding.UTF8, 1024, true)) // LeaveOpen = true
                    {
                        writer.AutoFlush = true; // 自动刷新
                        try
                        {
                            // 对于StreamReader.ReadLine()，客户端发送时需要添加换行符
                            // 如果客户端仍然使用PrintWriter.close()，那么ReadToEnd()仍然适用
                            // 但为了与Java客户端的readLine()兼容，这里假设客户端发送的是行数据
                            string request = reader.ReadLine(); // 改为ReadLine()以匹配Java客户端的readLine()
                            if (request != null)
                            {
                                Console.WriteLine("Message from client: " + request);

                                string responseString = "Server Response from C#\n"; // 添加换行符
                                writer.Write(responseString); // 使用StreamWriter发送
                                Console.WriteLine("Sending response back: " + responseString.Trim());
                            }
                            else
                            {
                                Console.WriteLine("Client disconnected or sent empty message.");
                            }
                        }
                        catch (IOException ex)
                        {
                            Console.WriteLine("Client disconnected unexpectedly: " + ex.Message);
                        }
                        catch (Exception e)
                        {
                            Console.WriteLine("Error during communication: " + e.Message);
                        }
                    } // using 块会自动关闭StreamReader/Writer，但如果LeaveOpen=true则不会关闭底层流
                    tcpClient.Close(); // 关闭客户端连接
                    Console.WriteLine("Client disconnected.");
                }
            }
            catch (SocketException se)
            {
                Console.WriteLine("Socket exception: " + se.Message);
            }
            catch (Exception ex)
            {
                Console.WriteLine("Server error: " + ex.Message);
            }
            finally
            {
                tcpListener?.Stop();
                Console.WriteLine("C# Server stopped.");
            }