JAVA实现客户端通过服务端对话（NET）

通过使用java.net实现客户端向服务端发送信息内容以及发送目标地址ID，服务端通过寻找对应ID转发给目标客户端。

代码仅供参考，其中有很多地方仍需要优化，比如：ID无法注册、没有添加密码、代码优化不够等问题

java版本：17

服务端代码：

import java.io.IOException;
import java.io.PrintWriter;
import java.net.*;
import java.util.*;

public class Sever {
    public static Sever Instance;
    private static  int port = 9999;
    private String[] id = {"1", "2", "3", "4", "5"};//ID为固定ID，可根据需求添加或更改
    Map<String, PrintWriter> land_id = new HashMap<>();
    //判断账号输入是否存在
    public boolean JudgeID(String id_)
    {
        for(int i = 0;i < id.length;i++)
        {
            if(Objects.equals(id_, id[i]))
            {
                return true;
            }
        }
        return false;
    }

    public void AddLandID(String id_, PrintWriter writer)
    {
        land_id.put(id_,writer);
    }


    public static void main(String[] args) throws IOException {
        Instance = new Sever();//通过使用单例来实现其他模块代码调用
        ServerSocket serverSocket = new ServerSocket(port);
        System.out.println("服务器已启动，等待客户端连接...");
        //死循环使服务端一直运行
        while (true) {
            Socket clientSocket = null; // 接受客户端连接
            try {
                clientSocket = serverSocket.accept();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            new ClientWorking(clientSocket).start(); //为每个客户端创建一个新的线程处理
        }
    }
}

客户端进程代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Objects;

public class ClientWorking extends Thread {
    private Socket clientSocket;
    private String clientId;
    private BufferedReader reader;
    private PrintWriter writer;

    private String aimId;


    public ClientWorking(Socket socket) {
        this.clientSocket = socket;
    }

    //重写进程运行代码，主要包括对客户端发送的信息进行处理
    @Override
    public void run() {
        try {
            reader = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
            writer = new PrintWriter(clientSocket.getOutputStream(), true);
            // 登录过程，接收客户端ID
            while(true)
            {
                writer.println("请输入你的ID(输入/q断开连接):");//ID为服务端指定ID
                clientId = reader.readLine();
                if (Sever.Instance.JudgeID(clientId)) {
                    Sever.Instance.AddLandID(clientId, writer);
                    System.out.println(clientId + " 已连接.");
                    while(true)
                    {
                        writer.println("请输入你要发送信息到的目标ID:");
                        aimId = reader.readLine();
                        if (Objects.equals(aimId, "/q"))
                        {
                            System.out.println(clientId + " 已断开.");
                            return;
                        }
                        else if (Sever.Instance.land_id.containsKey(aimId)) {
                            String message;
                            while (true)
                            {
                                writer.println("(输入q退出)->");
                                if((message = reader.readLine()) != null)
                                {
                                    System.out.println("收到来自 " + clientId + " 的消息: " + message);
                                    if(message.equals("q"))
                                    {
                                        break;
                                    }
                                    else
                                    {
                                        PrintWriter targetWriter = (Sever.Instance.land_id.get(aimId));
                                        targetWriter.println(clientId + ": " + message);
                                    }
                                }
                            }
                        }
                        else
                        {
                            writer.println("未找到用户,请再次输入(输入/q退出)");
                        }
                    }
                }
                else if (Objects.equals(clientId, "/q"))
                {
                    System.out.println(clientId + " 已断开.");
                    return;
                }
                else
                {
                    writer.println("输入id错误，请重新输入");
                }
            }

        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }
}

客户端代码：

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Objects;
import java.util.Scanner;

public class Client {
    private static final String SERVER_ADDRESS = "localhost";
    private static final int SERVER_PORT = 9999;

    public static void main(String[] args) {
        try (Socket socket = new Socket(SERVER_ADDRESS, SERVER_PORT);
             BufferedReader consoleReader = new BufferedReader(new InputStreamReader(System.in));
             BufferedReader serverReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
             PrintWriter serverWriter = new PrintWriter(socket.getOutputStream(), true)) {
            System.out.println("连接到服务器成功.");
            // 登录
            System.out.println(serverReader.readLine()); // 服务器发送登录提示
            Scanner in = new Scanner(System.in);
            String clientId = in.next();
            serverWriter.println(clientId);
            if (clientId.equalsIgnoreCase("/q")) {
                serverWriter.println(clientId);
                return;
            }

            // 新建线程持续接收服务器反馈的消息
            new Thread(() -> {
                try {
                    String serverMessage;
                    while ((serverMessage = serverReader.readLine()) != null) {
                        System.out.println(serverMessage); // 打印来自服务器的消息1

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

            // 死循环持续检测发送消息
            while (true) {
                //System.out.print("请输入消息 (格式: 目标ID: 消息内容) 或 输入 'exit' 退出: ");
                String message = consoleReader.readLine();
                serverWriter.println(message);
                if (message.equalsIgnoreCase("/q")) {
                    serverWriter.println(message);
                    break;
                }
            }

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