本工具类采用websocket连接，将用户名做为key将每个通道的Session存储到全局Map集合，当需要将消息通知到指定用户时，从Map取得socket通道并发送消息。示例代码如下：

@Component
@ServerEndpoint("/websocket/{userName}")
public class WebSocket {

    private Session session;
    
    private static CopyOnWriteArraySet<WebSocket> webSockets =new CopyOnWriteArraySet<>();
    private static Map<String,Session> sessionPool = new HashMap<String,Session>();
    
    @OnOpen
    public void onOpen(Session session, @PathParam(value="userName")String userName) {
        this.session = session;
        webSockets.add(this);
        sessionPool.put(userName, session);
        System.out.println("【websocket消息】有新用户" + userName +"接入，当前在线总数为:"+webSockets.size());
    }
    
    @OnClose
    public void onClose() {
    	try {
    		webSockets.remove(this);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println("【websocket消息】连接断开，总数为:"+webSockets.size());
    }
    
    @OnMessage
    public void onMessage(String message) {
        System.out.println("【websocket消息】收到客户端消息:"+message);
    }
    
    // 此为广播消息-集体通知
    public void sendAllMessage(String message) {
        for(WebSocket webSocket : webSockets) {
            System.out.println("【websocket消息】广播消息:"+message);
            try {
                webSocket.session.getAsyncRemote().sendText(message);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    
    // 此为单点消息-单用户通知
    public void sendOneMessage(String userName, String message) {
    	 System.out.println("【websocket消息】单点消息:"+message);
        Session session = sessionPool.get(userName);
        if (session != null) {
            try {
                session.getAsyncRemote().sendText(message);
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
    
}