基于WebSocket实现无URL存储的灵活安全服务器-客户端通信教程

import java.util.concurrent.ConcurrentHashMap;
import org.springframework.web.socket.WebSocketSession;

public class ChatWebSocketHandler {

    // 存储活跃的WebSocketSession，键为用户ID，值为WebSocketSession
    private final ConcurrentHashMap<String, WebSocketSession> activeSessions = new ConcurrentHashMap<>();

    // 当新的WebSocket连接建立时
    public void handleNewConnection(WebSocketSession session) {
        // 在实际应用中，这里需要进行用户认证
        // 假设通过某种方式获取到用户ID
        String userId = authenticateAndGetUserId(session); 
        if (userId != null) {
            activeSessions.put(userId, session);
            System.out.println("用户 " + userId + " 已连接.");
        } else {
            // 认证失败，关闭连接
            try {
                session.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    // 当WebSocket连接关闭时
    public void handleConnectionClose(WebSocketSession session) {
        // 移除已关闭的会话
        activeSessions.entrySet().removeIf(entry -> entry.getValue().equals(session));
        System.out.println("连接已关闭.");
    }

    // 广播消息给所有连接的用户
    public void broadcastMessage(String message) {
        activeSessions.forEach((userId, session) -> {
            try {
                if (session.isOpen()) {
                    session.sendMessage(new TextMessage(message));
                }
            } catch (IOException e) {
                System.err.println("发送消息到用户 " + userId + " 失败: " + e.getMessage());
            }
        });
    }

    // 发送私有消息给特定用户
    public void sendPrivateMessage(String targetUserId, String message) {
        WebSocketSession session = activeSessions.get(targetUserId);
        if (session != null && session.isOpen()) {
            try {
                session.sendMessage(new TextMessage(message));
                System.out.println("私有消息发送给 " + targetUserId + ": " + message);
            } catch (IOException e) {
                System.err.println("发送私有消息到用户 " + targetUserId + " 失败: " + e.getMessage());
            }
        } else {
            System.out.println("用户 " + targetUserId + " 不在线或会话无效。");
        }
    }

    // 模拟认证过程
    private String authenticateAndGetUserId(WebSocketSession session) {
        // 实际中可能从session属性、HTTP握手头或首次消息中获取认证信息
        // 这里简化为从session ID派生
        return "user_" + session.getId().substring(0, 5); 
    }
}

import io.socket.client.IO;
import io.socket.client.Socket;
import io.socket.emitter.Emitter;

public class ChatClient {

    private Socket socket;

    public void connect(String url) {
        try {
            socket = IO.socket(url);

            socket.on(Socket.EVENT_CONNECT, new Emitter.Listener() {
                @Override
                public void call(Object... args) {
                    System.out.println("连接成功！");
                    socket.emit("message", "Hello from Java Client!"); // 发送消息
                }
            }).on("chat message", new Emitter.Listener() { // 监听服务器发送的聊天消息
                @Override
                public void call(Object... args) {
                    System.out.println("收到消息: " + args[0]);
                }
            }).on(Socket.EVENT_DISCONNECT, new Emitter.Listener() {
                @Override
                public void call(Object... args) {
                    System.out.println("连接断开！");
                }
            }).on(Socket.EVENT_CONNECT_ERROR, new Emitter.Listener() {
                @Override
                public void call(Object... args) {
                    System.err.println("连接错误: " + args[0]);
                }
            });

            socket.connect();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    public void sendMessage(String event, String data) {
        if (socket != null && socket.connected()) {
            socket.emit(event, data);
        } else {
            System.out.println("Socket未连接，无法发送消息。");
        }
    }

    public void disconnect() {
        if (socket != null) {
            socket.disconnect();
        }
    }

    public static void main(String[] args) {
        ChatClient client = new ChatClient();
        client.connect("http://localhost:3000"); // 假设Socket.io服务器运行在3000端口

        // 模拟发送消息
        try {
            Thread.sleep(2000); // 等待连接建立
            client.sendMessage("chat message", "你好，这是一个测试消息！");
            Thread.sleep(5000); // 保持连接一段时间
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            client.disconnect();
        }
    }
}