Bio model realizes multi person chat

1、 Server side

package com.li.server;

import jdk.net.Sockets;

import javax.sound.sampled.Port;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.HashMap;
import java.util.Map;

/**
 * @author liyakun
 */
public class ChatServer {
    
    private int DEFAULT_PORT = 8886;
    private final String QUIT = "quit";
    private ServerSocket serverSocket;
    private Map<Integer, Writer> connectedClients;

    public ChatServer() {
    
        connectedClients = new HashMap<Integer, Writer>();
    }

    public synchronized void addClient(Socket socket) throws IOException {
    
        if (socket != null) {
    
            int port = socket.getPort();
            BufferedWriter bufferedWriter = new BufferedWriter(
                    new OutputStreamWriter(socket.getOutputStream())
            );
            connectedClients.put(port, bufferedWriter);
            System.out.println(" Port number ：" + port + " Connected to server ");
        }
    }

    public synchronized void removeServer(Socket socket) throws IOException {
    
        if (socket != null) {
    
            int port = socket.getPort();
            if (connectedClients.containsKey(port)) {
    
                connectedClients.get(port).close();
            }
            connectedClients.remove(port);
            System.out.println(" client " + port + " Offline ");
        }
    }

    public synchronized void forwardMessage(Socket socket, String fwdMsg) throws IOException {
    
        for (Integer integer : connectedClients.keySet()) {
    
            if (!integer.equals(socket.getPort())) {
    
                Writer writer = connectedClients.get(integer);
                writer.write(fwdMsg);
                writer.flush();
            }
        }
    }

    /**
     *  Check whether the user exits 
     * @param msg
     * @return
     */
    public boolean readyToQuit(String msg) {
    
        return QUIT.equals(msg);
    }

    public void close() {
    
        if (serverSocket != null) {
    
            try {
    
                serverSocket.close();
                System.out.println(" close serverSocket");
            } catch (IOException e) {
    
                e.printStackTrace();
            }
        }
    }

    public void start() {
    
        try {
    
            serverSocket = new ServerSocket(DEFAULT_PORT);
            System.out.println(" Server startup , Listening port " + DEFAULT_PORT);
            while (true) {
    
                // Wait for the client to connect 
                Socket socket = serverSocket.accept();
                // establish chatHandler Threads 
                new Thread(new ChatHandler(this,socket)).start();
            }
        } catch (IOException e) {
    
            e.printStackTrace();
        } finally {
    
            close();
        }
    }

    public static void main(String[] args) {
    
        ChatServer chatServer = new ChatServer();
        chatServer.start();
    }
}

package com.li.server;

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

/**
 * @author liyakun
 */
public class ChatHandler implements Runnable {
    
    private ChatServer chatServer;
    private Socket socket;

    public ChatHandler(ChatServer chatServer, Socket socket) {
    
        this.chatServer = chatServer;
        this.socket = socket;
    }

    @Override
    public void run() {
    
        try {
    
            // Store new online users 
            chatServer.addClient(socket);
            // Read the information sent by the user 
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            String msg=null;
            while ((msg=bufferedReader.readLine())!=null){
    
                String fwdMsg=" client 【"+socket.getPort()+"]"+msg+"\n";
                System.out.println(fwdMsg);
                chatServer.forwardMessage(socket,fwdMsg);
                // Check whether the user exits 
                if(chatServer.readyToQuit(msg)){
    
                    break;
                }
            }
        } catch (IOException e) {
    
            e.printStackTrace();
        }finally {
    
            try {
    
                chatServer.removeServer(socket);
            } catch (IOException e) {
    
                e.printStackTrace();
            }
        }
    }
}

2、 client

package com.li.client;

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

/**
 * @author liyakun
 */
public class ChatClient {
    
    private final String DEFAULT_SERVER_HOST = "127.0.0.1";
    private final int DEFAULT_SERVER_PORT = 8886;
    private final String QUIT = "quit";
    private Socket socket;
    private BufferedReader reader;
    private BufferedWriter writer;

    // Send information to the server 
    public void send(String msg) throws IOException {
    
        if (!socket.isOutputShutdown()) {
    
            writer.write(msg + "\n");
            writer.flush();
        }
    }

    public String receive() throws IOException {
    
        String msg = null;
        if (!socket.isInputShutdown()) {
    
            msg = reader.readLine();
        }
        return msg;
    }

    // Check whether the user is ready to exit 
    public boolean readyToQuit(String msg) {
    
        return QUIT.equals(msg);
    }

    public void close() {
    
        if (writer != null) {
    
            try {
    
                System.out.println(" close socket");
                writer.close();
            } catch (IOException e) {
    
                e.printStackTrace();
            }
        }
    }

    public void start() {
    

        try {
    
            // establish socket
            socket = new Socket(DEFAULT_SERVER_HOST, DEFAULT_SERVER_PORT);

            // establish IO flow 
            reader = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            writer = new BufferedWriter(new OutputStreamWriter(socket.getOutputStream()));
            // Processing user input 
            new Thread(new UserInputHandler(this)).start();
            // Read the information forwarded by the server 
            String msg = null;
            while ((msg = receive()) != null) {
    
                System.out.println(msg);
            }
        } catch (IOException e) {
    
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
    
        ChatClient chatClient = new ChatClient();
        chatClient.start();
    }
}

package com.li.client;

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

/**
 * @author liyakun
 */
public class UserInputHandler implements Runnable {
    
    private ChatClient chatClient;

    public UserInputHandler(ChatClient chatClient) {
    
        this.chatClient = chatClient;
    }

    @Override
    public void run() {
    
        try {
     // Waiting for user input 
            BufferedReader consoleReader =
                    new BufferedReader(new InputStreamReader(System.in));
            while (true) {
    

                String input = consoleReader.readLine();
                // Send a message to the server 
                chatClient.send(input);
                // Check whether the user is ready to exit 
                if (chatClient.readyToQuit(input)) {
    
                    break;
                }
            }
        } catch (IOException e) {
    
            e.printStackTrace();
        }
    }
}

3、 test ：
stay IDEA Running server in , And open multiple clients （ Opening method editConfigurations------>Allow parallel run）, You can test successfully .