文章目錄

• 任務要求
• 實現代碼
• • 工具類
  • 服務器端線程
  • 客戶端線程
  • 服務器端程序
  • 客戶端程序
• 運行說明

任務要求

編寫一個簡單的Socket多客戶端聊天程序：

• 客戶端程序，從控制臺輸入字符串，發送到服務器端，并將服務器返回的信息顯示出來
• 服務器端程序，從客戶機接收數據并打印，同時將從標準輸入獲取的信息發送給客戶機
• 滿足一個服務器可以服務多個客戶

低配版本鏈接

實現代碼

工具類

import java.io.DataOutputStream; import java.io.IOException; import java.io.OutputStream; import java.net.Socket;public class SocketUtils {public static void writeToSocket(Socket socket, String message) throws IOException {writeToOutputStream(socket.getOutputStream(), message);}public static void writeToDataOutputStream(DataOutputStream dos, String message) throws IOException {dos.writeUTF(message);dos.flush();}public static void writeToOutputStream(OutputStream os, String message) throws IOException {writeToDataOutputStream(new DataOutputStream(os), message);}}

服務器端線程

import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; import java.net.Socket; import java.text.SimpleDateFormat; import java.util.Date; import java.util.Map;public class ChatServerRunnable implements Runnable {private Socket socket;private DataOutputStream dos;private DataInputStream dis;private String currentUserNickName;public ChatServerRunnable(Socket socket) throws IOException {this.socket = socket;this.dos = new DataOutputStream(socket.getOutputStream());this.dis = new DataInputStream(socket.getInputStream());}@Overridepublic void run() {try {write("歡迎來到聊天室！");login();System.out.println(currentUserNickName + "用戶登錄成功");write(currentUserNickName + "， 您已登錄。\n輸入【list users】可以查看當前登錄用戶列表\n輸入【to all 消息內容】可以群發消息\n輸入【to 某個用戶 消息內容】可以給指定用戶發送消息\n輸入【exit】可以退出聊天");String input = dis.readUTF();while (!ChatServer.EXIT.equals(input)) {System.out.println(currentUserNickName + "輸入了" + input);if (input.startsWith("to ")) {sendMessage(input);} else if ("list users".equals(input)) {showOnlineUsers();} else {write("您輸入的命令不合法，請重新輸入！");}input = dis.readUTF();}} catch (IOException e) {e.printStackTrace();} finally {ChatServer.nickNameSocketMap.remove(currentUserNickName);try {dis.close();} catch (IOException e) {e.printStackTrace();}try {dos.close();} catch (IOException e) {e.printStackTrace();}try {socket.close();} catch (IOException e) {e.printStackTrace();}}}private void login() throws IOException {write("請輸入你的昵稱：");while (true) {String nickName = dis.readUTF();System.out.println("用戶輸入了昵稱：" + nickName);synchronized (ChatServerRunnable.class) {if (!ChatServer.nickNameSocketMap.containsKey(nickName)) {currentUserNickName = nickName;ChatServer.nickNameSocketMap.put(nickName, socket);break;} else {write("您輸入的昵稱已存在，請重新輸入：");}}}}private void sendMessage(String input) throws IOException {int receiverEndIndex = input.indexOf(" ", 3);String receiver = input.substring(3, receiverEndIndex);String message = input.substring(receiverEndIndex + 1);if ("all".equals(receiver)) {broadcast(message);} else {sendIndividualMessage(receiver, message);}}private void sendIndividualMessage(String receiver, String orignalMessage) throws IOException {Socket receiverSocket = ChatServer.nickNameSocketMap.get(receiver);if (receiverSocket != null) {SocketUtils.writeToSocket(receiverSocket, formatMessage("你", orignalMessage));} else {write("您要單獨聊天的用戶【" + receiver + "】不存在或者已經下線");}}private String formatMessage(String receiver, String originalMessage) {StringBuilder messageBuilder = new StringBuilder();messageBuilder.append(currentUserNickName).append(" 對 ").append(receiver).append(" 說：\n").append(originalMessage).append("\n發送時間：").append(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date()));return messageBuilder.toString();}private void broadcast(String orignalMessage) throws IOException {for (Map.Entry<String, Socket> entry : ChatServer.nickNameSocketMap.entrySet()) {if (!currentUserNickName.equals(entry.getKey())) {SocketUtils.writeToSocket(entry.getValue(), formatMessage("所有人", orignalMessage));}}}private void showOnlineUsers() throws IOException {StringBuilder users = new StringBuilder();users.append("當前在線的用戶有：\n");for (String nickName : ChatServer.nickNameSocketMap.keySet()) {users.append("【").append(nickName).append("】\n");}write(users.toString());}private void write(String message) throws IOException {SocketUtils.writeToDataOutputStream(dos, message);}}

客戶端線程

import java.io.DataInputStream; import java.io.IOException;public class ClientMessageReceiver implements Runnable {private DataInputStream dis;private boolean timeToStop = false;public ClientMessageReceiver(DataInputStream dis) {this.dis = dis;}@Overridepublic void run() {while (!timeToStop) {try {System.out.println(dis.readUTF());} catch (IOException e) {if ("Connection reset".equals(e.getMessage())) {System.out.println("與服務器的連接已中斷！");break;}if (!timeToStop) {e.printStackTrace(); }}}}public void stop() {timeToStop = true;}}

服務器端程序

import java.io.IOException; import java.net.ServerSocket; import java.net.Socket; import java.util.HashMap; import java.util.Map;public class ChatServer {public static final String EXIT = "exit";public static final int PORT = 8888;static Map<String, Socket> nickNameSocketMap = new HashMap<>();public static void main(String[] args) {try (ServerSocket ss = new ServerSocket(PORT)) {System.out.println("聊天室服務器端已啟動，正在監聽" + PORT + "端口");while (true) {try {Socket socket = ss.accept();System.out.println("有新用戶連接到服務器端，信息為：" + socket);new Thread(new ChatServerRunnable(socket)).start();} catch (Exception e) {e.printStackTrace();}}} catch (IOException e) {e.printStackTrace();}}}

客戶端程序

import java.io.DataInputStream; import java.io.DataOutputStream; import java.io.IOException; import java.net.Socket; import java.util.Scanner;public class ChatClient {private static Scanner scanner = new Scanner(System.in);public static void main(String[] args) {try (Socket socket = new Socket("127.0.0.1", 8888);DataInputStream dis = new DataInputStream(socket.getInputStream());DataOutputStream dos = new DataOutputStream(socket.getOutputStream())) {ClientMessageReceiver messageReceiver = new ClientMessageReceiver(dis);new Thread(messageReceiver).start();String input = null;do {input = scanner.nextLine();write(dos, input);} while (!ChatServer.EXIT.equals(input));messageReceiver.stop();} catch (IOException e) {e.printStackTrace();}}private static void write(DataOutputStream dos, String message) throws IOException {dos.writeUTF(message);dos.flush();}}

運行說明

啟動服務器：

啟動第一個客戶端，輸入客戶昵稱：

服務器監聽到了這個事件：

獲取所有用戶列表，發送給所有用戶“hhh”的信息：

服務器端接收到了這個事件：

新的客戶端登錄，注冊用戶昵稱：

服務器接收到這個事件：

用戶1向用戶2發送私聊消息：

用戶2收到用戶1的消息：

客戶2向所有用戶發送消息：

客戶1收到客戶2的群發消息：

服務器監聽到了這些事件：

客戶2退出：

客戶1顯示的在線列表只有1人了：

客戶1也退出：

客戶端用戶退出的時候，該線程終止。
沒客戶端用戶，服務器也正常跑自己的事。

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