import java.io.IOException;
import java.io.PrintWriter;
import java.net.Socket;
import java.util.Scanner;

/**
 * @Author Tiam
 * @Date 2022/11/4 21:06
 * @Description:
 */
public class Client1 {
    public static void main(String[] args) {

        try {
            Socket socket = new Socket("localhost", 8888);
            System.out.println(socket);
            // 开启读取消息的线程, 使其可以一直读取消息
            new Thread(new ClientThread(socket)).start();

            // 输出流 用于向服务端发送消息
            PrintWriter out = new PrintWriter(socket.getOutputStream(), true);
            // 输入流
            Scanner scanner = new Scanner(System.in);
            while (true) {
                // System.out.print("请输入:");
                String message = scanner.nextLine();
                out.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.net.Socket;

/**
 * @Author Tiam
 * @Date 2022/11/6 22:06
 * @Description: 读取消息
 */
public class ClientThread implements Runnable {
    Socket socket;

    public ClientThread(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        boolean isExit = true;
        while (isExit) {
            try {
                readMessage();
            } catch (Exception e) {
                System.out.println("服务器断开连接");
                isExit = false;
                System.exit(-1);
            }
        }
    }

    /**
     * 线程: 读取其他用户的消息
     */
    private void readMessage() throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
        System.out.println("\n正在等待返回消息... ");
        String message = in.readLine();
        System.out.println(message);
    }

}

import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashMap;
import java.util.Map;

/**
 * @Author Tiam
 * @Date 2022/11/4 21:10
 * @Description: 服务端启动类
 */
public class RunServer {
    public static Map<Socket, String> map = new HashMap<>();

    public static void main(String[] args) {
        ServerSocket serverSocket = null;
        Socket socket = null;
        try {
            serverSocket = new ServerSocket(8888);
            System.out.println("服务端已启动, 等待连接...");
            int num = 0;
            while (true) {
                socket = serverSocket.accept();
                map.put(socket, null);
                System.out.println(socket+"已连接, "+(++num)+"号用户");
                new Thread(new ServerThread(socket)).start();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

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

/**
 * @Author Tiam
 * @Date 2022/11/4 21:10
 * @Description:
 */
public class ServerThread implements Runnable {
    private Socket socket;

    public ServerThread(Socket socket) {
        this.socket = socket;
    }

    @Override
    public void run() {
        while (true) {
            send();
        }
    }

    private void send() {
        try {
            BufferedReader in = null;
            PrintWriter out = null;
            in = new BufferedReader(new InputStreamReader(socket.getInputStream()));

            String mes = null;
            try {
                mes = in.readLine();
            } catch (IOException e) {
                System.out.println("客户端异常关闭");
                e.printStackTrace();
                System.exit(-1);
            }
            // 判断是否是否为私发, 截取端口号5位
            String to = null;
            if (mes.length() > 5) {
                to = mes.substring(0, 5);

                // 找到端口目标端口 to, 向其发送消息后停止执行
                for (Socket socket1 : RunServer.map.keySet()) {
                    if (to.equals(String.valueOf(socket1.getPort()))) {
                        out = new PrintWriter(socket1.getOutputStream(), true);
                        out.println(mes.substring(5));
                        return;
                    }
                }
            }

            
            // 如未找到目标端口, 按群发消息处理, 转发给所有在线的客户端
            String message = "【群发消息】" + socket.getPort() + ":" + mes;
            System.out.println(message);
            // 将某个客户端发送过来的消息, 转发给所有在线用户
            for (Socket socket1 : RunServer.map.keySet()) {
                // 跳过自己
                if (socket1 == this.socket) continue;
                out = new PrintWriter(socket1.getOutputStream(), true);
                out.println(message);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }


}