Java实现简单的多人聊天程序

Server端代码实现

Server端只实现简单的消息转发功能，为每一个客户端建立一个Thread，处理该客户端的消息转发。

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.ServerSocket;
import java.net.Socket;
import java.util.ArrayList;

/**
 * Created by sandy on 10/03/2017.
 */
public class MultiChatServer {

    ArrayList<ClientThread> clients = new ArrayList<ClientThread>();

    public static void main(String args []) {

        new MultiChatServer().start();
    }

    public void start() {

        try {

            boolean iConnect = false;
            ServerSocket serverSocket = new ServerSocket(20013);
            iConnect = true;

            while (iConnect) {

                Socket socket = serverSocket.accept();

                ClientThread currentClient = new ClientThread(socket);
                clients.add(currentClient);
                new Thread(currentClient).start();
            }

        } catch (IOException e) {

            e.printStackTrace();

        }
    }

    class ClientThread implements Runnable{

        private Socket socket;
        private DataInputStream dis;
        private DataOutputStream dos;
        private String str;
        private Boolean iConnect = false;

        ClientThread(Socket socket) {
            this.socket = socket;
            iConnect = true;
        }

        public void run() {
            try {

                while (iConnect) {

                    dis = new DataInputStream(socket.getInputStream());
                    str = dis.readUTF();
                    int currentIndex = 0;

                    for (int i=0; i<clients.size(); i++) {
                        if (clients.get(i).equals(this)) {
                            currentIndex = i;
                            break;
                        }
                    }

                    for (int i = 0; i < clients.size(); i++) {
                        ClientThread clientThread = clients.get(i);
                        if (!clientThread.equals(this)) {
                            clientThread.sendMsg("Client-" + currentIndex + ": " + str);
                        }

                    }
                }
            } catch (IOException e) {

                e.printStackTrace();
            }
        }

        public void sendMsg(String str) {

            try {

                dos = new DataOutputStream(this.socket.getOutputStream());
                dos.writeUTF(str);

            } catch (IOException e) {

                e.printStackTrace();
            }
        }

    }
}

Client端代码实现

Client端需要启动两个线程，一个负责发送消息，一个负责接收消息，互不干扰。

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.net.Socket;
import java.util.Scanner;

/**
 * Created by sandy on 10/03/2017.
 */
public class MultiChatClient {

    private Socket socket;
    private DataInputStream dis;
    private DataOutputStream dos;
    private Scanner scanner;

    public static void main(String args[]) {

        new MultiChatClient().start();
    }

    public void start() {

        try {

            socket = new Socket("localhost", 20013);

            dis = new DataInputStream(this.socket.getInputStream());
            dos = new DataOutputStream(this.socket.getOutputStream());
            scanner = new Scanner(System.in);

            new Thread(new SendThread()).start();
            new Thread(new RecThread()).start();

        } catch (Exception e) {

            e.printStackTrace();
        }

    }

    class SendThread implements Runnable {

        private String str;
        private Boolean iConnect = false;


        public void run() {
            iConnect = true;
            try {
                while (iConnect) {
                    str = scanner.nextLine();
                    if (null == str || "".equals(str.trim()) || str.isEmpty() || str.length() == 0) {
                        continue;
                    } else {
                        dos.writeUTF(str);
                        System.out.println("I: " + str);
                    }

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

    class RecThread implements Runnable {

        private String str;
        private Boolean iConnect = false;

        public void run() {
            iConnect = true;
            try {
                while (iConnect) {
                    str = dis.readUTF();
                    System.out.println(str);
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}