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24 - WebSocket 实时通信

版本说明

本文档基于 LangChain4j 1.10.0 版本编写。

学习目标

通过本章节学习，你将能够：

理解 WebSocket 在 LLM 应用中的作用
掌握 LangChain4j 与 Spring WebSocket 的集成
学会实现实时流式聊天
理解事件驱动架构和 SSE 流
掌握连接管理和消息广播
实现一个完整的实时聊天应用

前置知识

完成《01 - LangChain4j 简介》章节
完成《12 - 流式输出详解》章节
WebSocket 基础知识
Spring Boot WebSocket 基础

核心概念

WebSocket 在 LLM 应用中的优势

传统 REST API vs WebSocket：

特性	REST API	WebSocket
通信模式	请求-响应	全双工实时
延迟	较高（每次请求）	极低（持久连接）
资源消耗	HTTP 开销	初始握手后开销极小
流式输出	需要轮询或 SSE	原生支持
实时性	差	优秀
连接数	无状态	有状态连接

LLM 应用场景：

实时对话（ChatGPT 风格体验）
实时代码补全和生成
实时协作（多人同时编辑）
实时翻译和字幕
实时语音转文字

架构设计

┌─────────────────────────────────────────────────────────┐
│                  WebSocket 架构                          │
├─────────────────────────────────────────────────────────┤
│                                                             │
│  ┌─────────┐    ┌────────────┐    ┌───────────┐  │
│  │  Client │    │  WebSocket │    │  Handler   │  │
│  │ Browser │◄──►│  Endpoint    │◄──►│  & Service │  │
│  └─────────┘    └────────────┘    └─────┬─────┘  │
│                                   │              │       │
│                                   │         ┌───┘       │
│                                   │         │            │
│                                   │     ┌─────┐       │
│                                   │     │Chat  │       │
│                                   └────►│Model │       │
│                                         └─────┘       │
│                                       │
│                                   ┌───────┐   │
│                                   │Memory │   │
│                                   └───────┘   │
│                                               │
└─────────────────────────────────────────────────────┘

Spring WebSocket 配置

Maven 依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-websocket</artifactId>
</dependency>

WebSocket 配置类

package com.example.langchat.config;

import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.config.annotation.EnableWebSocket;
import org.springframework.web.socket.config.annotation.WebSocketConfigurer;
import org.springframework.web.socket.config.annotation.WebSocketHandlerRegistry;

/**
 * WebSocket 配置
 */
@Configuration
@EnableWebSocket
public class WebSocketConfig implements WebSocketConfigurer {

    @Override
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        // 注册 WebSocket 处理器
        registry.addHandler(new ChatWebSocketHandler(), "/ws/chat")
                .setAllowedOrigins("*");  // 生产环境应该指定具体域名
    }
}

WebSocket 处理器

基础 WebSocket 处理器

package com.example.langchat.websocket;

import dev.langchain4j.model.chat.ChatModel;
import dev.langchain4j.service.AiServices;
import dev.langchain4j.service.SystemMessage;
import dev.langchain4j.service.UserMessage;
import dev.langchain4j.service.V;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * WebSocket 处理器
 */
@Component
public class ChatWebSocketHandler extends TextWebSocketHandler {

    private static final Logger logger = LoggerFactory.getLogger(ChatWebSocketHandler.class);

    // 会话存储：Session ID -> Session 信息
    private final Map<String, SessionInfo> sessions = new ConcurrentHashMap<>();

    // 用户会话：User ID -> Session ID
    private final Map<String, String> userSessions = new ConcurrentHashMap<>();

    // AI 服务
    private ChatModel chatModel;

    /**
     * 构造函数
     */
    @Autowired
    public ChatWebSocketHandler(ChatModel chatModel) {
        this.chatModel = chatModel;
        
        // 创建 AI 助手
        this.assistant = createAssistant();
    }

    /**
     * AI 助手
     */
    @AiService
    public interface Assistant {
        String chat(@UserMessage String message);
    }

    private Assistant assistant;

    /**
     * 创建 AI 助手
     */
    private Assistant createAssistant() {
        return AiServices.builder(Assistant.class)
                .chatModel(chatModel)
                .systemMessageProvider(chatMemoryId -> 
                    "你是一个友好、乐于助人的 AI 助手。" +
                    "请用简洁、自然的语言回答用户的问题。" +
                    "保持对话的上下文连贯性。"
                )
                .build();
    }

    @Override
    public void afterConnectionEstablished(WebSocketSession session, 
                                             Map<String, Object> attributes) throws Exception {
        logger.info("WebSocket 连接建立: Session ID = {}", session.getId());

        // 创建会话信息
        SessionInfo sessionInfo = new SessionInfo();
        sessionInfo.setSessionId(session.getId());
        sessionInfo.setUserId((String) attributes.get("userId"));
        sessionInfo.setConnectTime(System.currentTimeMillis());
        sessionInfo.setLastActivityTime(System.currentTimeMillis());

        // 存储会话
        sessions.put(session.getId(), sessionInfo);

        // 存储用户会话
        String userId = sessionInfo.getUserId();
        if (userId != null) {
            userSessions.put(userId, session.getId());
        }

        // 发送欢迎消息
        session.sendMessage(new TextMessage("欢迎连接！你可以开始聊天了。"));
    }

    @Override
    protected void handleTextMessage(WebSocketSession session, 
                                         TextMessage message) throws Exception {
        String sessionId = session.getId();
        String userId = sessions.get(sessionId).getUserId();
        String text = message.getPayload();

        logger.info("收到消息: Session ID = {}, User ID = {}, Text = {}", 
                    sessionId, userId, text);

        try {
            // 更新活动时间
            sessions.get(sessionId).setLastActivityTime(System.currentTimeMillis());

            // 使用 AI 助手生成响应
            String response = assistant.chat(text);

            // 发送响应
            session.sendMessage(new TextMessage(response));

            logger.info("发送响应: {}", response);

        } catch (Exception e) {
            logger.error("处理消息失败: {}", e.getMessage());
            
            // 发送错误消息
            session.sendMessage(new TextMessage("抱歉，处理您的消息时出错了。"));
        }
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, 
                                       CloseStatus closeStatus, 
                                       Map<String, Object> attributes) throws Exception {
        String sessionId = session.getId();
        String userId = sessions.get(sessionId).getUserId();

        logger.info("WebSocket 连接关闭: Session ID = {}, User ID = {}, Status = {}", 
                    sessionId, userId, closeStatus);

        // 移除会话
        sessions.remove(sessionId);

        // 移除用户会话
        if (userId != null) {
            userSessions.remove(userId);
        }

        // 记录会话时长
        SessionInfo sessionInfo = sessions.get(sessionId);
        if (sessionInfo != null) {
            long duration = System.currentTimeMillis() - sessionInfo.getConnectTime();
            logger.info("会话时长: {} 秒", duration / 1000);
        }
    }

    @Override
    public void handleTransportError(WebSocketSession session, 
                                       Throwable exception) throws Exception {
        logger.error("WebSocket 传输错误: Session ID = {}, Error: {}", 
                    session.getId(), exception.getMessage());

        // 发送错误消息（如果可能）
        try {
            if (session.isOpen()) {
                session.sendMessage(new TextMessage("连接出现错误，正在重连..."));
            }
        } catch (IOException e) {
            logger.error("发送错误消息失败", e);
        }
    }

    /**
     * 获取会话信息
     */
    public SessionInfo getSessionInfo(String sessionId) {
        return sessions.get(sessionId);
    }

    /**
     * 获取用户会话
     */
    public String getUserSessionId(String userId) {
        return userSessions.get(userId);
    }

    /**
     * 获取所有活跃会话
     */
    public Map<String, SessionInfo> getAllSessions() {
        return new ConcurrentHashMap<>(sessions);
    }

    /**
     * 发送广播消息
     */
    public void broadcastMessage(String message) {
        for (WebSocketSession session : sessions.values()) {
            try {
                session.sendMessage(new TextMessage(message));
            } catch (IOException e) {
                logger.error("发送广播消息失败: Session ID = {}", 
                            session.getSessionId(), e);
            }
        }
    }

    /**
     * 发送给特定用户
     */
    public void sendToUser(String userId, String message) {
        String sessionId = userSessions.get(userId);
        if (sessionId != null) {
            SessionInfo sessionInfo = sessions.get(sessionId);
            if (sessionInfo != null && sessionInfo.getSession().isOpen()) {
                try {
                    sessionInfo.getSession().sendMessage(new TextMessage(message));
                } catch (IOException e) {
                    logger.error("发送用户消息失败: User ID = {}, Session ID = {}", 
                                userId, sessionId, e);
                }
            }
        }
    }

    /**
     * 会话信息
     */
    public static class SessionInfo {
        private String sessionId;
        private String userId;
        private long connectTime;
        private long lastActivityTime;
        private WebSocketSession session;

        // Getters and Setters
        public String getSessionId() { return sessionId; }
        public void setSessionId(String sessionId) { this.sessionId = sessionId; }
        
        public String getUserId() { return userId; }
        public void setUserId(String userId) { this.userId = userId; }
        
        public long getConnectTime() { return connectTime; }
        public void setConnectTime(long connectTime) { this.connectTime = connectTime; }
        
        public long getLastActivityTime() { return lastActivityTime; }
        public void setLastActivityTime(long lastActivityTime) { 
            this.lastActivityTime = lastActivityTime; 
        }
        
        public WebSocketSession getSession() { return session; }
        public void setSession(WebSocketSession session) { this.session = session; }
    }
}

流式响应集成

流式 WebSocket 处理器

package com.example.langchat.websocket;

import dev.langchain4j.model.chat.StreamingChatModel;
import dev.langchain4j.service.AiServices;
import dev.langchain4j.service.SystemMessage;
import dev.langchain4j.service.UserMessage;
import dev.langchain4j.model.chat.response.StreamingChatResponseHandler;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import org.springframework.web.socket.CloseStatus;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;
import org.springframework.web.socket.handler.TextWebSocketHandler;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.function.Consumer;

/**
 * 流式 WebSocket 处理器
 */
@Component
public class StreamingChatWebSocketHandler extends TextWebSocketHandler {

    private static final Logger logger = LoggerFactory.getLogger(StreamingChatWebSocketHandler.class);

    private final Map<String, SessionInfo> sessions = new ConcurrentHashMap<>();
    private final Map<String, String> userSessions = new ConcurrentHashMap<>();

    private StreamingChatModel streamingChatModel;

    /**
     * AI 助手接口
     */
    @AiService
    public interface StreamingAssistant {
        String chat(@UserMessage String message);
    }

    private StreamingAssistant streamingAssistant;

    @Autowired
    public StreamingChatWebSocketHandler(StreamingChatModel model) {
        this.streamingChatModel = model;
        this.streamingAssistant = createAssistant();
    }

    /**
     * 创建流式 AI 助手
     */
    private StreamingAssistant createAssistant() {
        return AiServices.builder(StreamingAssistant.class)
                .streamingChatModel(streamingChatModel)
                .systemMessageProvider(chatMemoryId -> 
                    "你是一个流式 AI 助手。" +
                    "请以流式方式生成响应，" +
                    "逐个 Token 发送内容。" +
                    "保持自然、流畅的输出。"
                )
                .build();
    }

    @Override
    public void afterConnectionEstablished(WebSocketSession session, 
                                             Map<String, Object> attributes) {
        logger.info("流式 WebSocket 连接建立: {}", session.getId());

        SessionInfo sessionInfo = new SessionInfo();
        sessionInfo.setSessionId(session.getId());
        sessionInfo.setUserId((String) attributes.get("userId"));
        sessionInfo.setConnectTime(System.currentTimeMillis());

        sessions.put(session.getId(), sessionInfo);

        String userId = sessionInfo.getUserId();
        if (userId != null) {
            userSessions.put(userId, session.getId());
        }

        session.sendMessage(new TextMessage("已连接到流式聊天服务！"));
    }

    @Override
    protected void handleTextMessage(WebSocketSession session, 
                                         TextMessage message) {
        String sessionId = session.getId();
        String text = message.getPayload();

        logger.info("收到流式消息: Session ID = {}, Text = {}", sessionId, text);

        try {
            // 开始流式生成
            session.sendMessage(new TextMessage("AI: "));

            StringBuilder fullResponse = new StringBuilder();

            streamingAssistant.chat(text);

        } catch (Exception e) {
            logger.error("处理流式消息失败", e);
            try {
                session.sendMessage(new TextMessage("处理失败，请重试。"));
            } catch (IOException io) {
                logger.error("发送错误消息失败", io);
            }
        }
    }

    /**
     * 发送 Token 到客户端
     */
    private void sendToken(WebSocketSession session, String token) {
        try {
            session.sendMessage(new TextMessage(token));
        } catch (IOException e) {
            logger.error("发送 Token 失败: {}", e.getMessage());
        }
    }

    /**
     * 发送流式响应（使用 TokenStream）
     */
    public void streamResponse(WebSocketSession session, String prompt) {
        logger.info("开始流式生成: Session ID = {}, Prompt = {}", 
                    session.getId(), prompt);

        streamingchatModel.chat(prompt, new Consumer<String>() {
            @Override
            public void accept(String token) {
                sendToken(session, token);
            }
        });
    }

    @Override
    public void afterConnectionClosed(WebSocketSession session, 
                                       CloseStatus closeStatus, 
                                       Map<String, Object> attributes) {
        String sessionId = session.getId();
        String userId = sessions.get(sessionId).getUserId();

        logger.info("流式 WebSocket 连接关闭: Session ID = {}, User ID = {}", 
                    sessionId, userId);

        sessions.remove(sessionId);
        if (userId != null) {
            userSessions.remove(userId);
        }
    }

    @Override
    public void handleTransportError(WebSocketSession session, 
                                       Throwable exception) {
        logger.error("流式 WebSocket 传输错误: {}", exception.getMessage());
    }

    /**
     * 发送广播消息
     */
    public void broadcastMessage(String message) {
        for (SessionInfo sessionInfo : sessions.values()) {
            if (sessionInfo.getSession().isOpen()) {
                try {
                    sessionInfo.getSession().sendMessage(new TextMessage(message));
                } catch (IOException e) {
                    logger.error("发送广播失败: {}", sessionInfo.getSessionId());
                }
            }
        }
    }

    /**
     * 发送给特定用户
     */
    public void sendToUser(String userId, String message) {
        String sessionId = userSessions.get(userId);
        if (sessionId != null) {
            SessionInfo sessionInfo = sessions.get(sessionId);
            if (sessionInfo != null && sessionInfo.getSession().isOpen()) {
                try {
                    sessionInfo.getSession().sendMessage(new TextMessage(message));
                } catch (IOException e) {
                    logger.error("发送用户消息失败: User ID = {}, Session ID = {}", 
                                userId, sessionId, e);
                }
            }
        }
    }

    /**
     * 获取会话信息
     */
    public SessionInfo getSessionInfo(String sessionId) {
        return sessions.get(sessionId);
    }

    /**
     * 会话信息
     */
    public static class SessionInfo {
        private String sessionId;
        private String userId;
        private long connectTime;
        private long lastActivityTime;
        private WebSocketSession session;

        // Getters and Setters
        public String getSessionId() { return sessionId; }
        public void setSessionId(String sessionId) { this.sessionId = sessionId; }
        public String getUserId() { return userId; }
        public void setUserId(String userId) { this.userId = userId; }
        public long getConnectTime() { return connectTime; }
        public void setConnectTime(long connectTime) { this.connectTime = connectTime; }
        public long getLastActivityTime() { return lastActivityTime; }
        public void setLastActivityTime(long lastActivityTime) { 
            this.lastActivityTime = lastActivityTime; 
        }
        public WebSocketSession getSession() { return session; }
        public void setSession(WebSocketSession session) { this.session = session; }
    }
}

连接管理

会话管理器

package com.example.langchat.websocket;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.stereotype.Component;

import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * 会话管理器
 */
@Component
public class SessionManager {

    private static final Logger logger = LoggerFactory.getLogger(SessionManager.class);

    // 所有会话
    private final Map<String, SessionInfo> sessions = new ConcurrentHashMap<>();

    // 用户到会话的映射
    private final Map<String, String> userSessions = new ConcurrentHashMap<>();

    // 房间（Group Chat）
    private final Map<String, List<String>> rooms = new ConcurrentHashMap<>();

    /**
     * 添加会话
     */
    public void addSession(String sessionId, String userId, String username) {
        SessionInfo info = new SessionInfo();
        info.setSessionId(sessionId);
        info.setUserId(userId);
        info.setUsername(username);
        info.setConnectTime(System.currentTimeMillis());
        info.setLastActivityTime(System.currentTimeMillis());

        sessions.put(sessionId, info);
        userSessions.put(userId, sessionId);

        logger.info("添加会话: Session ID = {}, User ID = {}, Username = {}", 
                    sessionId, userId, username);
    }

    /**
     * 移除会话
     */
    public void removeSession(String sessionId) {
        SessionInfo info = sessions.get(sessionId);
        if (info != null) {
            userSessions.remove(info.getUserId());
            sessions.remove(sessionId);

            logger.info("移除会话: Session ID = {}, User ID = {}", 
                        sessionId, info.getUserId());
        }
    }

    /**
     * 更新用户会话
     */
    public void updateUserSession(String userId, String newSessionId) {
        String oldSessionId = userSessions.get(userId);
        if (oldSessionId != null) {
            // 移除旧会话
            sessions.remove(oldSessionId);
        }

        userSessions.put(userId, newSessionId);
        logger.info("更新用户会话: User ID = {}, 新 Session ID = {}", 
                    userId, newSessionId);
    }

    /**
     * 获取会话信息
     */
    public SessionInfo getSessionInfo(String sessionId) {
        return sessions.get(sessionId);
    }

    /**
     * 获取用户会话
     */
    public String getUserSessionId(String userId) {
        return userSessions.get(userId);
    }

    /**
     * 获取所有会话
     */
    public Map<String, SessionInfo> getAllSessions() {
        return new ConcurrentHashMap<>(sessions);
    }

    /**
     * 获取所有在线用户
     */
    public List<String> getOnlineUsers() {
        return new CopyOnWriteArrayList<>(userSessions.keySet());
    }

    /**
     * 获取会话数量
     */
    public int getSessionCount() {
        return sessions.size();
    }

    /**
     * 获取用户数量
     */
    public int getUserCount() {
        return userSessions.size();
    }

    /**
     * 添加到房间
     */
    public void joinRoom(String userId, String roomId) {
        if (!rooms.containsKey(roomId)) {
            rooms.put(roomId, new CopyOnWriteArrayList<>());
        }

        List<String> roomUsers = rooms.get(roomId);
        if (!roomUsers.contains(userId)) {
            roomUsers.add(userId);
            logger.info("用户 {} 加入房间 {}", userId, roomId);
        }
    }

    /**
     * 离开房间
     */
    public void leaveRoom(String userId, String roomId) {
        List<String> roomUsers = rooms.get(roomId);
        if (roomUsers != null) {
            roomUsers.remove(userId);
            logger.info("用户 {} 离开房间 {}", userId, roomId);
        }
    }

    /**
     * 获取房间用户
     */
    public List<String> getRoomUsers(String roomId) {
        return rooms.get(roomId);
    }

    /**
     * 广播消息到房间
     */
    public void broadcastToRoom(String roomId, String message) {
        List<String> roomUsers = rooms.get(roomId);
        if (roomUsers != null) {
            for (String userId : roomUsers) {
                String sessionId = userSessions.get(userId);
                if (sessionId != null) {
                    SessionInfo info = sessions.get(sessionId);
                    if (info != null && info.getSession().isOpen()) {
                        try {
                            info.getSession().sendMessage(new TextMessage(message));
                        } catch (IOException e) {
                            logger.error("发送房间消息失败: Room ID = {}, User ID = {}", 
                                        roomId, userId, e);
                        }
                    }
                }
            }
        }
    }

    /**
     * 获取会话统计
     */
    public SessionStats getStats() {
        return new SessionStats(
            getSessionCount(),
            getUserCount(),
            rooms.size()
        );
    }

    /**
     * 会话统计
     */
    public static class SessionStats {
        private final int sessionCount;
        private final int userCount;
        private final int roomCount;

        public SessionStats(int sessionCount, int userCount, int roomCount) {
            this.sessionCount = sessionCount;
            this.userCount = userCount;
            this.roomCount = roomCount;
        }

        public int getSessionCount() { return sessionCount; }
        public int getUserCount() { return userCount; }
        public int getRoomCount() { return roomCount; }

        @Override
        public String toString() {
            return String.format("SessionStats{sessions=%d, users=%d, rooms=%d}",
                        sessionCount, userCount, roomCount);
        }
    }

    /**
     * 会话信息
     */
    public static class SessionInfo {
        private String sessionId;
        private String userId;
        private String username;
        private long connectTime;
        private long lastActivityTime;
        private WebSocketSession session;

        // Getters and Setters
        public String getSessionId() { return sessionId; }
        public void setSessionId(String sessionId) { this.sessionId = sessionId; }
        public String getUserId() { return userId; }
        public void setUserId(String userId) { this.userId = userId; }
        public String getUsername() { return username; }
        public void setUsername(String username) { this.username = username; }
        public long getConnectTime() { return connectTime; }
        public void setConnectTime(long connectTime) { this.connectTime = connectTime; }
        public long getLastActivityTime() { return lastActivityTime; }
        public void setLastActivityTime(long lastActivityTime) { 
            this.lastActivityTime = lastActivityTime; 
        }
        public WebSocketSession getSession() { return session; }
        public void setSession(WebSocketSession session) { this.session = session; }
    }
}

前端集成

JavaScript 客户端

// WebSocket 客户端
class ChatWebSocket {
    constructor(url) {
        this.url = url;
        this.ws = null;
        this.reconnectAttempts = 0;
        this.maxReconnectAttempts = 5;
        this.reconnectInterval = 5000; // 5 秒
    }

    /**
     * 连接 WebSocket
     */
    connect() {
        try {
            console.log(`连接到 WebSocket: ${this.url}`);
            
            this.ws = new WebSocket(this.url);
            
            this.ws.onopen = (event) => {
                console.log('WebSocket 连接已建立');
                this.reconnectAttempts = 0;
                this.onConnected(event);
            };
            
            this.ws.onmessage = (event) => {
                console.log(`收到消息: ${event.data}`);
                this.onMessage(event);
            };
            
            this.ws.onerror = (event) => {
                console.error('WebSocket 错误:', event);
                this.onError(event);
                this.attemptReconnect();
            };
            
            this.ws.onclose = (event) => {
                console.log('WebSocket 连接已关闭');
                this.onClosed(event);
                
                // 如果不是正常关闭，尝试重连
                if (!event.wasClean) {
                    this.attemptReconnect();
                }
            };

        } catch (error) {
            console.error('连接 WebSocket 失败:', error);
            this.attemptReconnect();
        }
    }

    /**
     * 发送消息
     */
    sendMessage(message) {
        if (this.ws && this.ws.readyState === WebSocket.OPEN) {
            console.log(`发送消息: ${message}`);
            this.ws.send(message);
        } else {
            console.warn('WebSocket 未连接，无法发送消息');
            this.attemptReconnect();
        }
    }

    /**
     * 断开连接
     */
    disconnect() {
        if (this.ws) {
            console.log('断开 WebSocket 连接');
            this.ws.close();
            this.ws = null;
        }
    }

    /**
     * 尝试重连
     */
    attemptReconnect() {
        if (this.reconnectAttempts < this.maxReconnectAttempts) {
            this.reconnectAttempts++;
            const delay = this.reconnectInterval * this.reconnectAttempts;
            
            console.log(`尝试重连 (${this.reconnectAttempts}/${this.maxReconnectAttempts}), 延迟: ${delay}ms`);
            
            setTimeout(() => {
                this.connect();
            }, delay);
        } else {
            console.error('已达到最大重试次数，停止重连');
            this.onMaxReconnectAttemptsReached();
        }
    }

    /**
     * 重置重连计数
     */
    resetReconnectAttempts() {
        this.reconnectAttempts = 0;
    }

    /**
     * 连接回调（可重写）
     */
    onConnected(event) {
        // 触发自定义事件
        this.triggerEvent('connected', event);
    }

    onMessage(event) {
        // 解析消息类型
        try {
            const data = JSON.parse(event.data);
            
            if (data.type === 'chat') {
                this.onChatMessage(data.message, data.sender);
            } else if (data.type === 'stream') {
                this.onStreamToken(data.token);
            } else if (data.type === 'error') {
                this.onError(data.message);
            } else if (data.type === 'system') {
                this.onSystemMessage(data.message);
            }
        } catch (error) {
            // 不是 JSON，当作普通文本处理
            this.onTextMessage(event.data);
        }
    }

    onError(event) {
        console.error('WebSocket 错误:', event);
        this.triggerEvent('error', event);
    }

    onClosed(event) {
        console.log('WebSocket 已关闭:', event);
        this.triggerEvent('closed', event);
    }

    onMaxReconnectAttemptsReached() {
        console.warn('已达到最大重试次数');
        this.triggerEvent('maxReconnectAttempts', {});
    }

    onChatMessage(message, sender) {
        console.log(`聊天消息: ${sender}: ${message}`);
        this.triggerEvent('chat', { message, sender });
    }

    onStreamToken(token) {
        console.log(`流式 Token: ${token}`);
        this.triggerEvent('token', { token });
    }

    onTextMessage(text) {
        console.log(`文本消息: ${text}`);
        this.triggerEvent('text', { text });
    }

    onSystemMessage(message) {
        console.log(`系统消息: ${message}`);
        this.triggerEvent('system', { message });
    }

    /**
     * 触发自定义事件
     */
    triggerEvent(eventName, data) {
        const event = new CustomEvent(eventName, data);
        window.dispatchEvent(event);
    }
}

/**
 * 自定义事件
 */
class CustomEvent extends Event {
    constructor(eventName, detail) {
        super(eventName, { detail });
        this.detail = detail;
    }

    get detail() {
        return this.detail;
    }
}

// 使用示例
const chatWebSocket = new ChatWebSocket('ws://localhost:8080/ws/chat');

// 连接
chatWebSocket.connect();

// 发送消息
chatWebSocket.sendMessage('你好，请介绍一下自己');

// 监听消息
window.addEventListener('chat', (event) => {
    console.log(`收到聊天消息: ${event.detail.message}`);
    displayMessage(event.detail.sender, event.detail.message);
});

window.addEventListener('token', (event) => {
    console.log(`收到 Token: ${event.detail.token}`);
    appendToken(event.detail.token);
});

window.addEventListener('system', (event) => {
    console.log(`系统消息: ${event.detail.message}`);
    showSystemMessage(event.detail.message);
});

window.addEventListener('error', (event) => {
    console.error(`错误: ${event.detail}`);
    showErrorMessage(event.detail);
});

window.addEventListener('closed', (event) => {
    console.log('连接已关闭');
    onConnectionClosed();
});

// 断开连接
// chatWebSocket.disconnect();

function displayMessage(sender, message) {
    const chatContainer = document.getElementById('chat-container');
    const messageDiv = document.createElement('div');
    messageDiv.className = 'message';
    messageDiv.innerHTML = `
        <div class="sender">${sender}</div>
        <div class="content">${message}</div>
    `;
    chatContainer.appendChild(messageDiv);
}

function appendToken(token) {
    const currentMessage = document.querySelector('.message:last-child .content');
    if (currentMessage) {
        currentMessage.textContent += token;
    }
}

function showSystemMessage(message) {
    const chatContainer = document.getElementById('chat-container');
    const messageDiv = document.createElement('div');
    messageDiv.className = 'message system';
    messageDiv.textContent = message;
    chatContainer.appendChild(messageDiv);
}

function showErrorMessage(error) {
    const errorDiv = document.getElementById('error-message');
    errorDiv.textContent = error.message || '连接错误';
    errorDiv.style.display = 'block';
}

function onConnectionClosed() {
    const statusDiv = document.getElementById('connection-status');
    statusDiv.textContent = '未连接';
    statusDiv.className = 'status disconnected';
}

// 页面加载时自动连接
window.onload = () => {
    console.log('页面已加载，连接 WebSocket...');
    chatWebSocket.connect();
};

HTML 页面

<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>LangChain4j WebSocket 聊天</title>
    <style>
        body {
            font-family: Arial, sans-serif;
            margin: 0;
            padding: 0;
            display: flex;
            flex-direction: column;
            height: 100vh;
        }

        .header {
            background-color: #2c3e50;
            color: white;
            padding: 20px;
            text-align: center;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
        }

        .header h1 {
            margin: 0;
            font-size: 24px;
        }

        .status {
            margin-top: 10px;
            font-size: 14px;
        }

        .status.connected {
            color: #27ae60;
        }

        .status.disconnected {
            color: #e74c3c;
        }

        .chat-container {
            flex: 1;
            overflow-y: auto;
            padding: 20px;
            background-color: #f9f9f9;
        }

        .message {
            margin-bottom: 15px;
            padding: 10px;
            background-color: white;
            border-radius: 8px;
            box-shadow: 0 1px 3px rgba(0,0,0,0.1);
        }

        .message.system {
            background-color: #ecf0f1;
            color: #7f8c8d;
            font-style: italic;
            text-align: center;
        }

        .message .sender {
            font-weight: bold;
            color: #2c3e50;
            margin-bottom: 5px;
        }

        .message .content {
            line-height: 1.6;
        }

        .input-area {
            padding: 20px;
            background-color: white;
            box-shadow: 0 -2px 5px rgba(0,0,0,0.1);
            display: flex;
            gap: 10px;
        }

        .input-area input {
            flex: 1;
            padding: 10px;
            border: 1px solid #ddd;
            border-radius: 4px;
            font-size: 14px;
        }

        .input-area button {
            padding: 10px 25px;
            background-color: #3498db;
            color: white;
            border: none;
            border-radius: 4px;
            cursor: pointer;
            font-size: 14px;
            font-weight: bold;
            transition: background-color 0.3s;
        }

        .input-area button:hover {
            background-color: #2980b9;
        }

        .error-message {
            display: none;
            padding: 15px;
            background-color: #f8d7da;
            color: #f2dede;
            text-align: center;
            margin: 20px;
            border-radius: 4px;
        }

        .typing-indicator {
            padding: 10px 20px;
            font-style: italic;
            color: #7f8c8d;
            display: none;
        }

        .typing-indicator.show {
            display: block;
        }
    </style>
</head>
<body>
    <div class="header">
        <h1>🤖 LangChain4j WebSocket 聊天</h1>
        <div class="status" id="connection-status">
            <span id="status-text">未连接</span>
        </div>
    </div>

    <div class="chat-container" id="chat-container">
        <!-- 消息将在这里显示 -->
    </div>

    <div class="typing-indicator" id="typing-indicator">
        AI 正在输入...
    </div>

    <div class="input-area">
        <input type="text" id="message-input" placeholder="输入消息..." autocomplete="off">
        <button id="send-button">发送</button>
        <button id="disconnect-button">断开</button>
    </div>

    <div class="error-message" id="error-message"></div>

    <script src="chat-websocket.js"></script>
    <script>
        const messageInput = document.getElementById('message-input');
        const sendButton = document.getElementById('send-button');
        const disconnectButton = document.getElementById('disconnect-button');
        const typingIndicator = document.getElementById('typing-indicator');
        const statusText = document.getElementById('status-text');
        const statusDiv = document.getElementById('connection-status');

        // 更新连接状态
        window.addEventListener('connected', () => {
            statusText.textContent = '已连接';
            statusDiv.className = 'status connected';
        });

        window.addEventListener('closed', () => {
            statusText.textContent = '未连接';
            statusDiv.className = 'status disconnected';
        });

        // 显示/隐藏输入提示
        window.addEventListener('token', () => {
            typingIndicator.classList.add('show');
        });

        window.addEventListener('chat', () => {
            typingIndicator.classList.remove('show');
        });

        // 发送消息
        function sendMessage() {
            const message = messageInput.value.trim();
            if (message) {
                chatWebSocket.sendMessage(message);
                messageInput.value = '';
            }
        }

        // 按钮点击事件
        sendButton.addEventListener('click', sendMessage);
        messageInput.addEventListener('keypress', (e) => {
            if (e.key === 'Enter') {
                sendMessage();
            }
        });

        // 断开连接
        disconnectButton.addEventListener('click', () => {
            chatWebSocket.disconnect();
        });
    </script>
</body>
</html>

测试代码

WebSocket 测试

package com.example.langchat.websocket;

import org.junit.jupiter.api.*;
import static org.junit.jupiter.api.Assertions.*;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.web.socket.TextMessage;
import org.springframework.web.socket.WebSocketSession;

import java.util.concurrent.CountDownLatch;
import java.util.concurrent.TimeUnit;

/**
 * WebSocket 测试
 */
@SpringBootTest
class WebSocketHandlerTest {

    @Autowired
    private ChatWebSocketHandler chatHandler;

    @Autowired
    private SessionManager sessionManager;

    @Test
    void should_handle_connection() throws Exception {
        // 创建 Mock Session
        WebSocketSession mockSession = mock(WebSocketSession.class);
        when(mockSession.getId()).thenReturn("test-session-123");
        when(mockSession.isOpen()).thenReturn(true);

        // 模拟连接建立
        chatHandler.afterConnectionEstablished(mockSession, Map.of("userId", "user123"));

        // 验证会话已创建
        assertEquals(1, sessionManager.getSessionCount());
        assertNotNull(sessionManager.getSessionInfo("test-session-123"));
        assertEquals("user123", sessionManager.getSessionInfo("test-session-123").getUserId());
    }

    @Test
    void should_handle_message() throws Exception {
        WebSocketSession mockSession = mock(WebSocketSession.class);
        when(mockSession.getId()).thenReturn("test-session-456");
        when(mockSession.isOpen()).thenReturn(true);

        // 模拟消息
        TextMessage message = new TextMessage("测试消息");
        chatHandler.handleTextMessage(mockSession, message);

        // 验证消息已处理
        SessionInfo info = sessionManager.getSessionInfo("test-session-456");
        assertNotNull(info);
        assertTrue(System.currentTimeMillis() - info.getLastActivityTime() < 1000);
    }

    @Test
    void should_handle_disconnect() throws Exception {
        WebSocketSession mockSession = mock(WebSocketSession.class);
        when(mockSession.getId()).thenReturn("test-session-789");
        when(mockSession.isOpen()).thenReturn(false);

        // 模拟关闭
        chatHandler.afterConnectionClosed(
            mockSession,
            CloseStatus.NORMAL,
            Map.of()
        );

        // 验证会话已移除
        assertNull(sessionManager.getSessionInfo("test-session-789"));
    }

    @Test
    void should_broadcast_message() throws Exception {
        // 创建多个会话
        for (int i = 0; i < 5; i++) {
            WebSocketSession mockSession = mock(WebSocketSession.class);
            when(mockSession.getId()).thenReturn("session-" + i);
            when(mockSession.isOpen()).thenReturn(true);
            sessionManager.addSession("session-" + i, "user-" + i, "用户" + i);
        }

        // 广播消息
        chatHandler.broadcastMessage("大家好！");

        // 验证所有会话都收到消息
        for (int i = 0; i < 5; i++) {
            WebSocketSession session = sessionManager.getSessionInfo("session-" + i).getSession();
            verify(session).sendMessage(any(TextMessage.class));
        }
    }

    @Test
    void should_send_to_specific_user() throws Exception {
        // 创建两个会话
        WebSocketSession mockSession1 = mock(WebSocketSession.class);
        WebSocketSession mockSession2 = mock(WebSocketSession.class);

        when(mockSession1.getId()).thenReturn("session-1");
        when(mockSession1.isOpen()).thenReturn(true);
        sessionManager.addSession("session-1", "user-1", "用户1");

        when(mockSession2.getId()).thenReturn("session-2");
        when(mockSession2.isOpen()).thenReturn(true);
        sessionManager.addSession("session-2", "user-2", "用户2");

        // 发送给特定用户
        chatHandler.sendToUser("user-1", "这是给用户1的消息");

        // 验证只有用户1 的会话收到消息
        verify(mockSession1).sendMessage(any(TextMessage.class));
        verify(mockSession2, never()).sendMessage(any(TextMessage.class));
    }

    @Test
    void should_handle_room_messages() throws Exception {
        // 创建房间
        String roomId = "room-123";
        
        // 添加用户到房间
        sessionManager.joinRoom("user-1", roomId);
        sessionManager.joinRoom("user-2", roomId);
        sessionManager.joinRoom("user-3", roomId);

        // 创建 Mock 会话
        for (String userId : List.of("user-1", "user-2", "user-3")) {
            String sessionId = sessionManager.getUserSessionId(userId);
            WebSocketSession mockSession = mock(WebSocketSession.class);
            when(mockSession.getId()).thenReturn(sessionId);
            when(mockSession.isOpen()).thenReturn(true);
            sessionManager.getSessionInfo(sessionId).setSession(mockSession);
        }

        // 广播到房间
        sessionManager.broadcastToRoom(roomId, "大家好！");

        // 验证房间内所有用户都收到消息
        verify(sessionManager.getSessionInfo(sessionManager.getUserSessionId("user-1")).getSession())
            .sendMessage(any(TextMessage.class));
        verify(sessionManager.getSessionInfo(sessionManager.getUserSessionId("user-2")).getSession())
            .sendMessage(any(TextMessage.class));
        verify(sessionManager.getSessionInfo(sessionManager.getUserSessionId("user-3")).getSession())
            .sendMessage(any(TextMessage.class));
    }

    @Test
    void should_handle_multiple_users_same_user() throws Exception {
        // 用户1 先登录
        sessionManager.addSession("session-1", "user-1", "用户1");

        // 用户1 再次登录（不同会话）
        WebSocketSession mockSession1 = mock(WebSocketSession.class);
        WebSocketSession mockSession2 = mock(WebSocketSession.class);

        when(mockSession1.getId()).thenReturn("session-1");
        when(mockSession1.isOpen()).thenReturn(true);

        when(mockSession2.getId()).thenReturn("session-2");
        when(mockSession2.isOpen()).thenReturn(true);

        sessionManager.updateUserSession("user-1", "session-2");
        sessionManager.getSessionInfo("session-2").setSession(mockSession2);

        // 发送消息给用户1
        chatHandler.sendToUser("user-1", "测试消息");

        // 验证只有新会话收到消息
        verify(mockSession1, never()).sendMessage(any(TextMessage.class));
        verify(mockSession2).sendMessage(any(TextMessage.class));
    }

    @Test
    void should_return_stats() {
        // 添加一些会话
        for (int i = 0; i < 10; i++) {
            sessionManager.addSession("session-" + i, "user-" + i, "用户" + i);
        sessionManager.joinRoom("user-" + i, "common-room");
        sessionManager.joinRoom("user-" + (i % 2), "private-room");
        sessionManager.joinRoom("user-" + (i % 3), "group-room");
        sessionManager.joinRoom("user-" + (i % 5), "special-room");
        sessionManager.joinRoom("user-" + i, "unique-room-" + i);
        sessionManager.joinRoom("user-" + i, "shared-room");
        sessionManager.joinRoom("user-" + i, "team-room");
        sessionManager.joinRoom("user-" + i, "work-room");
        sessionManager.joinRoom("user-" + i, "meeting-room");
        sessionManager.joinRoom("user-" + i, "project-room");
    }

    // 简化：实际测试中不会添加这么多房间
    SessionManager.SessionStats stats = sessionManager.getStats();

    assertEquals(10, stats.getSessionCount());
    assertEquals(10, stats.getUserCount());
    assertTrue(stats.getRoomCount() > 0);
}

实践练习

练习 1：实现多房间聊天

package com.example.langchat.websocket;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * 房间聊天
 */
public class RoomChat {

    private static final Logger logger = LoggerFactory.getLogger(RoomChat.class);

    private final Map<String, Room> rooms = new ConcurrentHashMap<>();
    private final Map<String, String> userRooms = new ConcurrentHashMap<>();

    /**
     * 创建房间
     */
    public String createRoom(String creatorId, String roomName, String description, int maxUsers) {
        String roomId = "room-" + System.currentTimeMillis() + "-" + Integer.toHexString((int) (Math.random() * 10000));

        Room room = new Room();
        room.setRoomId(roomId);
        room.setName(roomName);
        room.setDescription(description);
        room.setCreatorId(creatorId);
        room.setMaxUsers(maxUsers);
        room.setCreatedTime(System.currentTimeMillis());

        rooms.put(roomId, room);

        logger.info("创建房间: ID = {}, 名称 = {}, 创建者 = {}", 
                    roomId, roomName, creatorId);

        // 创建者自动加入
        joinRoom(creatorId, roomId);

        return roomId;
    }

    /**
     * 加入房间
     */
    public boolean joinRoom(String userId, String roomId) {
        Room room = rooms.get(roomId);

        if (room == null) {
            logger.warn("房间不存在: {}", roomId);
            return false;
        }

        if (room.getUsers().contains(userId)) {
            logger.info("用户 {} 已在房间 {}", userId, roomId);
            return true;
        }

        if (room.getUsers().size() >= room.getMaxUsers()) {
            logger.warn("房间 {} 已满", roomId);
            return false;
        }

        room.addUser(userId);
        userRooms.put(userId, roomId);

        logger.info("用户 {} 加入房间 {}", userId, roomId);

        // 通知房间其他用户
        broadcastToRoom(roomId, String.format("用户 %s 加入了聊天室", userId));

        return true;
    }

    /**
     * 离开房间
     */
    public boolean leaveRoom(String userId, String roomId) {
        Room room = rooms.get(roomId);

        if (room == null) {
            logger.warn("房间不存在: {}", roomId);
            return false;
        }

        room.removeUser(userId);
        userRooms.remove(userId);

        logger.info("用户 {} 离开房间 {}", userId, roomId);

        // 通知房间其他用户
        broadcastToRoom(roomId, String.format("用户 %s 离开了聊天室", userId));

        return true;
    }

    /**
     * 发送房间消息
     */
    public void sendToRoom(String userId, String roomId, String message) {
        Room room = rooms.get(roomId);

        if (room == null) {
            logger.warn("房间不存在: {}", roomId);
            return;
        }

        if (!room.getUsers().contains(userId)) {
            logger.warn("用户 {} 不在房间 {}", userId, roomId);
            return;
        }

        // 构建消息对象
        RoomMessage roomMessage = new RoomMessage();
        roomMessage.setUserId(userId);
        roomMessage.setRoomId(roomId);
        roomMessage.setMessage(message);
        roomMessage.setTimestamp(System.currentTimeMillis());

        // 广播到房间
        for (String roomUserId : room.getUsers()) {
            String sessionId = sessionManager.getUserSessionId(roomUserId);
            if (sessionId != null) {
                SessionInfo info = sessionManager.getSessionInfo(sessionId);
                if (info != null && info.getSession().isOpen()) {
                    try {
                        info.getSession().sendMessage(new TextMessage(roomMessage.toJson()));
                    } catch (IOException e) {
                        logger.error("发送房间消息失败: Room ID = {}, User ID = {}", 
                                    roomId, roomUserId, e);
                    }
                }
            }
        }
    }

    /**
     * 获取房间列表
     */
    public List<Room> getRoomList() {
        return new CopyOnWriteArrayList<>(rooms.values());
    }

    /**
     * 获取房间信息
     */
    public Room getRoomInfo(String roomId) {
        return rooms.get(roomId);
    }

    /**
     * 获取用户所在的房间
     */
    public String getUserRoomId(String userId) {
        return userRooms.get(userId);
    }

    /**
     * 广播到房间
     */
    private void broadcastToRoom(String roomId, String message) {
        Room room = rooms.get(roomId);

        if (room != null) {
            for (String userId : room.getUsers()) {
                String sessionId = sessionManager.getUserSessionId(userId);
                if (sessionId != null) {
                    SessionInfo info = sessionManager.getSessionInfo(sessionId);
                    if (info != null && info.getSession().isOpen()) {
                        try {
                            info.getSession().sendMessage(new TextMessage(message));
                        } catch (IOException e) {
                            logger.error("发送房间消息失败: Room ID = {}, User ID = {}", 
                                        roomId, userId, e);
                        }
                    }
                }
            }
        }
    }

    /**
     * 房间
     */
    public static class Room {
        private String roomId;
        private String name;
        private String description;
        private String creatorId;
        private int maxUsers;
        private long createdTime;
        private final List<String> users;
        private final List<RoomMessage> messages;

        public Room(String roomId, String name, String description, 
                      String creatorId, int maxUsers) {
            this.roomId = roomId;
            this.name = name;
            this.description = description;
            this.creatorId = creatorId;
            this.maxUsers = maxUsers;
            this.createdTime = System.currentTimeMillis();
            this.users = new CopyOnWriteArrayList<>();
            this.messages = new CopyOnWriteArrayList<>();
        }

        public void addUser(String userId) {
            users.add(userId);
        }

        public void removeUser(String userId) {
            users.remove(userId);
        }

        public void addMessage(RoomMessage message) {
            messages.add(message);
        }

        // Getters
        public String getRoomId() { return roomId; }
        public String getName() { return name; }
        public String getDescription() { return description; }
        public String getCreatorId() { return creatorId; }
        public int getMaxUsers() { return maxUsers; }
        public long getCreatedTime() { return createdTime; }
        public List<String> getUsers() { return new CopyOnWriteArrayList<>(users); }
        public List<RoomMessage> getMessages() { return new CopyOnWriteArrayList<>(messages); }
    }

    /**
     * 房间消息
     */
    public static class RoomMessage {
        private String messageId;
        private String userId;
        private String roomId;
        private String message;
        private long timestamp;

        public RoomMessage(String userId, String roomId, String message) {
            this.userId = userId;
            this.roomId = roomId;
            this.message = message;
            this.timestamp = System.currentTimeMillis();
        }

        // Getters and Setters
        public String getMessageId() { return messageId; }
        public void setMessageId(String messageId) { this.messageId = messageId; }
        public String getUserId() { return userId; }
        public void setUserId(String userId) { this.userId = userId; }
        public String getRoomId() { return roomId; }
        public void setRoomId(String roomId) { this.roomId = roomId; }
        public String getMessage() { return message; }
        public void setMessage(String message) { this.message = message; }
        public long getTimestamp() { return timestamp; }
        public void setTimestamp(long timestamp) { this.timestamp = timestamp; }

        public String toJson() {
            return String.format(
                "{\"messageId\":\"%s\",\"userId\":\"%s\",\"roomId\":\"%s\",\"message\":\"%s\",\"timestamp\":%d}",
                messageId,
                userId,
                roomId,
                message,
                timestamp
            );
        }
    }

    // 注入 SessionManager（需要修改 SessionManager 以支持此接口）
    private SessionManager sessionManager;

    public void setSessionManager(SessionManager sessionManager) {
        this.sessionManager = sessionManager;
    }

    public static void main(String[] args) {
        RoomChat roomChat = new RoomChat();

        // 创建房间
        String roomId = roomChat.createRoom(
            "user-123",
            "LangChain4j 爱好者",
            "讨论 LangChain4j 框架的使用和最佳实践",
            50
        );

        System.out.println("╔═══════════════════════════════════════════════════════════════════╗");
        System.out.println("║              房间聊天                              ║");
        System.out.println("╠═════════════════════════════════════════════════════════════════╣");
        System.out.println("║ 房间 ID: " + roomId);
        System.out.println("╠═══════════════════════════════════════════════════════════════════╣");
        System.out.println("║ 名称: LangChain4j 爱好者                               ║");
        System.out.println("║ 描述: 讨论 LangChain4j 框架的使用和最佳实践                       ║");
        System.out.println("║ 创建者: user-123                                          ║");
        System.out.println("║ 最大人数: 50                                                ║");
        System.out.println("╠═══════════════════════════════════════════════════════════════════╣");
        System.out.println("║ 用户列表:                                                ║");
        System.out.println("║   - user-123 (创建者)                                    ║");
        System.out.println("╠═══════════════════════════════════════════════════════════════════╣");
        System.out.println("║ 消息历史:                                                ║");
        System.out.println("║   暂无消息                                                  ║");
        System.out.println("╠═══════════════════════════════════════════════════════════════════╣");
        System.out.println("║ 创建时间: " + java.time.Instant.ofEpochMilli(rooms.get(roomId).getCreatedTime()) +
                          "                                                  ║");
        System.out.println("╚═════════════════════════════════════════════════════════════════════════════╝");
    }
}

总结

本章要点

WebSocket 优势
- 实时双向通信
- 低延迟连接
- 持久连接节省资源
- 原生支持流式输出
Spring WebSocket
- 注解配置
- 自动端点注册
- 消息处理器
- 拦截器支持
连接管理
- 会话状态跟踪
- 用户会话映射
- 心跳检测
- 断线重连
流式响应
- 逐 Token 输出
- 流式事件监听
- 进度反馈
- 错误恢复
最佳实践
- 实现心跳机制
- 限制消息频率
- 处理大量并发连接
- 实现消息队列
- 提供重连机制

下一步

在下一章节中，我们将学习：

高级流式处理
异步消息处理
消息队列集成
性能优化
安全和认证

常见问题

Q1：WebSocket 和 SSE 有什么区别？ A：主要区别：

WebSocket 是全双工，SSE 是单向
WebSocket 需要特殊握手，SSE 基于标准 HTTP
WebSocket 更复杂，SSE 更简单
WebSocket 适合实时对话，SSE 适合单向数据流
LLM 应用通常 WebSocket 更好，但 SSE 也可以

Q2：如何处理大量并发连接？ A：优化策略：

使用连接池
限制单用户连接数
实现负载均衡
使用异步处理
优化消息队列

Q3：如何实现消息持久化？ A：持久化方案：

数据库存储消息历史
Redis 缓存在线消息
消息队列处理离线消息
消息过期机制
分页加载历史

Q4：如何保证消息顺序？ A：保证方案：

单线程处理每个会话
使用有序消息队列
消息 ID 顺序递增
时间戳排序
客户端排序显示

Q5：如何处理网络中断？ A：处理策略：

实现心跳检测
客户端自动重连
服务器会话恢复
消息重发机制
离线消息存储

参考资料

版权归属于 LangChat Team
官网：https://langchat.cn

关于

基础入门

核心概念

高级功能

工程实践

生产部署

高级主题

WebSocket 实时通信

24 - WebSocket 实时通信

版本说明

学习目标

前置知识

核心概念

WebSocket 在 LLM 应用中的优势

架构设计

Spring WebSocket 配置

Maven 依赖

WebSocket 配置类

WebSocket 处理器

基础 WebSocket 处理器

流式响应集成

流式 WebSocket 处理器

连接管理

会话管理器

前端集成

JavaScript 客户端

HTML 页面

测试代码

WebSocket 测试

实践练习

练习 1：实现多房间聊天

总结

本章要点

下一步

常见问题

参考资料

关于

基础入门

核心概念

高级功能

工程实践

生产部署

高级主题

​24 - WebSocket 实时通信

​版本说明

​学习目标

​前置知识

​核心概念

​WebSocket 在 LLM 应用中的优势

​架构设计

​Spring WebSocket 配置

​Maven 依赖

​WebSocket 配置类

​WebSocket 处理器

​基础 WebSocket 处理器

​流式响应集成

​流式 WebSocket 处理器

​连接管理

​会话管理器

​前端集成

​JavaScript 客户端

​HTML 页面

​测试代码

​WebSocket 测试

​实践练习

​练习 1：实现多房间聊天

​总结

​本章要点

​下一步

​常见问题

​参考资料

24 - WebSocket 实时通信

版本说明

学习目标

前置知识

核心概念

WebSocket 在 LLM 应用中的优势

架构设计

Spring WebSocket 配置

Maven 依赖

WebSocket 配置类

WebSocket 处理器

基础 WebSocket 处理器

流式响应集成

流式 WebSocket 处理器

连接管理

会话管理器

前端集成

JavaScript 客户端

HTML 页面

测试代码

WebSocket 测试

实践练习

练习 1：实现多房间聊天

总结

本章要点

下一步

常见问题

参考资料