WebSocket 实战

1. 配置 WebSocketConfig

@Configuration
public class WebSocketConfig {

    @Bean
    public ServerEndpointExporter serverEndpointExporter(){
        return new ServerEndpointExporter();
    }

}

2. 创建 WebSocket 服务端

@Log4j2
@Component
@ServerEndpoint(value = "/api/websocket/queue/{userId}")
public class WebSocketQueue {


    // 当前会话（与某个客户端的连接会话，需要通过它来给客户端发送数据）
    private Session session;
    // 总会话集合：key:userId  value:Session
    private static Map sessionPool = new HashMap<>();
    // session 与 userId 关系集合：key:sessionId  value:userId
    private static Map sessionIds = new HashMap<>();

    
    @OnOpen
    public void onOpen(Session session, @PathParam(value = "userId") String userId){
        this.session = session;
        sessionPool.put(userId,session);
        sessionIds.put(session.getId(),userId);
        log.info("Queue-用户：{},新连接加入！当前在线人数为：{}",userId,getOnlineNum());
    }

    
    @OnClose
    public void onClose(){
        log.info("【webSocket-onClose】关闭连接调用session:{}",sessionIds);
        sessionPool.remove(sessionIds.get(session.getId())); //断开连接，移除用户
        sessionIds.remove(session.getId());                  //断开连接移除用户
        log.info("Queue-有一连接关闭！当前在线人数为" + getOnlineNum());
    }

    
    @OnMessage
    public void onMessage(String message, Session session) {
        if("ping".equals(message)){ log.info("Queue-定时请求，防止掉线；心跳sessionId:{},sessionName:{}",session.getId(),sessionIds.get(session.getId())); return;}
        log.info("Queue-来自客户端的消息:{}" , message);
        sendMessage(message,sessionIds.get(session.getId()));
    }

    
    @OnError
    public void onError(Session session, Throwable error){
        log.info("【webSocket-onError】发生错误时调用 session:{}",session);
        log.info("Queue-webSocket发生错误:session:{}-{}",session.getId(),error.getMessage());
        error.printStackTrace();
        throw new baseErrorException("TOPIC-onError发送客户信息失败，错误："+error.getMessage());
    }

    
    public static void sendMessage(String message,String userId) throws baseErrorException{
        log.info("【webSocket消息发送】发送号：{}-发送消息：{}",userId,message);
        Session s = sessionPool.get(userId);
        if (s!=null){
            try {
                s.getBasicRemote().sendText(message);
            } catch (IOException e) {
                log.info("【webSocket发送接口】Queue-发送客户信息失败，错误："+e.getMessage());
            }
        }
    }

    
    public synchronized int getOnlineNum() {
        return sessionPool.size();
    }

    
    public synchronized void getOnlineUsers() {
        for (String key : sessionIds.keySet()){
            log.info("Queue-所有在线用户:{}",sessionIds.get(key));
        }
    }

    
    public synchronized void sendAll(String msg) {
        for (String key : sessionIds.keySet()){
            sendMessage(msg,sessionIds.get(key));
        }
    }
}

3. 服务器给客户端发送消息

// 伪代码
WebSocketQueue.sendMessage(message, userId);

4. 客户端

    
webSocket  demo

    发送消息