virtual-patient/virtual-patient-web/src/main/java/com/supervision/controller/WebSocketServer.java

package com.supervision.controller;

import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

import javax.websocket.OnClose;
import javax.websocket.OnError;
import javax.websocket.OnOpen;
import javax.websocket.Session;
import javax.websocket.server.PathParam;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.atomic.AtomicInteger;

@Component
@Slf4j
@ServerEndpoint("/webSocket/{uid}")
public class WebSocketServer {

    //静态变量，用来记录当前在线连接数。应该把它设计成线程安全的。
    private static final AtomicInteger onlineNum = new AtomicInteger(0);

    //concurrent包的线程安全Set，用来存放每个客户端对应的WebSocketServer对象。
    private static final CopyOnWriteArraySet<Session> SESSION_POOL = new CopyOnWriteArraySet<Session>();

    /**
     * 有客户端连接成功
     */
    @OnOpen
    public void onOpen(Session session, @PathParam(value = "uid") String uid) {
        SESSION_POOL.add(session);
        onlineNum.incrementAndGet();
        log.info(uid + "加入webSocket！当前人数为" + onlineNum);
    }

    /**
     * 连接关闭调用的方法
     */
    @OnClose
    public void onClose(Session session) {
        SESSION_POOL.remove(session);
        int cnt = onlineNum.decrementAndGet();
        log.info("有连接关闭，当前连接数为：{}", cnt);
    }

    /**
     * 发送消息
     */
    public void sendMessage(Session session, String message) throws IOException {
        if (session != null) {
            synchronized (session) {
                session.getBasicRemote().sendText(message);
            }
        }
    }

    /**
     * 群发消息
     */
    public void broadCastInfo(String message) throws IOException {
        for (Session session : SESSION_POOL) {
            if (session.isOpen()) {
                sendMessage(session, message);
            }
        }
    }

    /**
     * 发生错误
     */
    @OnError
    public void onError(Session session, Throwable throwable) {
        log.error("发生错误");
        throwable.printStackTrace();
    }

    // 实现一个方法用于踢下线用户
    public void kickUser(String userId) {
        SESSION_POOL.removeIf(session -> session.getUserPrincipal().getName().equals(userId));
    }
}