使用视频地址

1、添加前端使用文件

2、后端配置

2.1添加依赖

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

2.2添加websocket配置类

import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.socket.server.standard.ServerEndpointExporter;

/**
 * websocket配置类
 */
@Configuration
public class WebSocketConfig {

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


}

2.3 添加WebSocketServer

package com.example.websocket.webSocket;

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

import javax.annotation.PostConstruct;
import javax.websocket.*;
import javax.websocket.server.ServerEndpoint;
import java.io.IOException;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.atomic.AtomicInteger;

/**
 *
 */
@Slf4j
@ServerEndpoint(value = "/websocket/asset")
@Component
public class WebSocketServer {


    @PostConstruct
    public void init() {
        log.info("=============websocket 加载===================");
    }

    private static final AtomicInteger ONLINE_COUNT = new AtomicInteger(0);
    /**
     * concurrent包的线程安全Set，用来存放每个客户端对应的Session对象。
     */
    private static final CopyOnWriteArraySet<Session> SESSION_SET = new CopyOnWriteArraySet<>();


    /**
     * 连接建立成功调用的方法
     */
    @OnOpen
    public void onOpen(Session session) {
        SESSION_SET.add(session);
        // 在线数加1
        int cnt = ONLINE_COUNT.incrementAndGet();
        log.info("有连接加入，当前连接数为：{}", cnt);
        sendMessage(session, "连接成功");
    }

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

    /**
     * 收到客户端消息后调用的方法
     *
     * @param message 客户端发送过来的消息
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        log.info("来自客户端的消息：{}", message);
        sendMessage(session, "收到消息，消息内容：" + message);

    }

    /**
     * 出现错误
     *
     * @param session session
     * @param error  error
     */
    @OnError
    public void onError(Session session, Throwable error) {
        log.error("发生错误：{}，Session ID： {}", error.getMessage(), session.getId());
        error.printStackTrace();
    }

    /**
     * 发送消息，实践表明，每次浏览器刷新，session会发生变化。
     *
     * @param session session
     * @param message message
     */
    public static void sendMessage(Session session, String message) {
        try {
            session.getBasicRemote().sendText(String.format("%s (From Server，Session ID=%s)", message, session.getId()));
        } catch (IOException e) {
            log.error("发送消息出错：{}", e.getMessage());
            e.printStackTrace();
        }
    }

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

    /**
     * 群发消息
     *
     * @param code  code
     * @throws IOException 异常
     */
    public static void broadCastInfoByCode(int code) throws IOException {
        for (Session session : SESSION_SET) {
            if (session.isOpen()) {
                sendMessageByCode(session, code);
            }
        }
    }


    /**
     * 发送消息 返回编码
     * @param session  session
     * @param code  code
     */
    public static void sendMessageByCode(Session session, int code) {
        try {
            session.getBasicRemote().sendObject(code);
        } catch (IOException | EncodeException e) {
            log.error("发送消息出错：{}", e.getMessage());
            e.printStackTrace();
        }
    }
    /**
     * 指定Session发送消息
     *
     * @param sessionId sessionId
     * @param message message
     * @throws IOException 异常
     */
    public static void sendMessage(String message, String sessionId) throws IOException {
        Session session = null;
        for (Session s : SESSION_SET) {
            if (s.getId().equals(sessionId)) {
                session = s;
                break;
            }
        }
        if (session != null) {
            sendMessage(session, message);
        } else {
            log.warn("没有找到你指定ID的会话：{}", sessionId);
        }
    }

}