WebSocket

在线工具

package com.demo.config.websocket;

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

@Configuration
public class WebSocketConfig {
    /**
     * 	注入ServerEndpointExporter，
     * 	这个bean会自动注册使用了@ServerEndpoint注解声明的Websocket endpoint
     */
    @Bean
    public ServerEndpointExporter serverEndpointExporter() {
        return new ServerEndpointExporter();
    }

}

package com.demo.config.websocket;


import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.TimeUnit;

import com.baomidou.mybatisplus.core.toolkit.CollectionUtils;
import com.baomidou.mybatisplus.core.toolkit.ObjectUtils;
import com.baomidou.mybatisplus.core.toolkit.StringUtils;
import com.demo.config.redis.RedisUtil;
import jakarta.annotation.Resource;
import jakarta.websocket.OnClose;
import jakarta.websocket.OnError;
import jakarta.websocket.OnMessage;
import jakarta.websocket.OnOpen;
import jakarta.websocket.Session;
import jakarta.websocket.server.PathParam;
import jakarta.websocket.server.ServerEndpoint;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.scheduling.annotation.Async;
import org.springframework.stereotype.Component;

import lombok.extern.slf4j.Slf4j;

@Component
@Slf4j
@ServerEndpoint("/websocket/{userId}")
public class WebSocket {

    /**
     * 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;
    /**
     * 用户ID
     */
    private String userId;

    /**
     * WebSocket是当前类名
     */
    private static CopyOnWriteArraySet<WebSocket> webSockets = new CopyOnWriteArraySet<>();
    /**
     * 用来存在线连接用户信息
     */
    private static ConcurrentHashMap<String, Session> sessionPool = new ConcurrentHashMap<String, Session>();

    private static String WEB_SOCKET_KEY = "web_socket_key_";

    /**
     * 链接成功调用的方法
     */
    @OnOpen
    public void onOpen(Session session, @PathParam(value = "userId") String userId) {
        try {
            this.session = session;
            this.userId = userId;
            webSockets.add(this);
            sessionPool.put(userId, session);

            // 缓存离线数据
            cacheMessageContains(userId);
            log.info("【websocket消息】有新的连接，总数为:" + webSockets.size());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 链接关闭调用的方法
     */
    @OnClose
    public void onClose() {
        try {
            webSockets.remove(this);
            sessionPool.remove(this.userId);
            log.info("【websocket消息】连接断开，总数为:" + webSockets.size());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    /**
     * 收到客户端消息后调用的方法
     *
     * @param message
     */
    @OnMessage
    public void onMessage(String message) {
        log.info("【websocket消息】收到客户端消息:" + message);
    }

    /**
     * 发送错误时的处理
     *
     * @param session
     * @param error
     */
    @OnError
    public void onError(Session session, Throwable error) {

        log.error("用户错误,原因:" + error.getMessage());
        error.printStackTrace();
    }


    // 此为广播消息
    public static void sendAllMessage(String message) {
        log.info("【websocket消息】广播消息:" + message);
        for (WebSocket webSocket : webSockets) {
            try {
                if (webSocket.session.isOpen()) {
                    webSocket.session.getAsyncRemote().sendText(message);
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }

    // 此为单点消息
    @Async
    public void sendOneMessage(String userId, String message) {
        if (sessionPool.size() <= 0 || ObjectUtils.isEmpty(sessionPool.get(userId))) {
            cacheMessagePut(userId, message);
        } else {
            Session session = sessionPool.get(userId);
            if (session != null && session.isOpen()) {
                try {
                    log.info("【websocket消息】 单点消息:" + message);
                    session.getAsyncRemote().sendText(message);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }
    }

    // 此为单点消息(多人)
    public void sendMoreMessage(String[] userIds, String message) {
        for (String userId : userIds) {
            Session session = sessionPool.get(userId);
            if (session != null && session.isOpen()) {
                try {
                    log.info("【websocket消息】 单点消息:" + message);
                    session.getAsyncRemote().sendText(message);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }

    }


    /**
     * 查询是否有离线消息并推送
     */
    public void cacheMessageContains(String userId) {

        String key = WEB_SOCKET_KEY + userId;
        List<String> range = new ArrayList();
        //是否有暂存的消息，如果有则发送消息
        if (RedisUtil.redis.hasKey(key)) {
            range = RedisUtil.redis.opsForList().range(key, 0, -1);
        }

        if (CollectionUtils.isNotEmpty(range) && range.size() > 0) {
            range.forEach(msg -> {
                sendOneMessage(userId, msg);
            });
            RedisUtil.redis.delete(key);
        }

    }


    /**
     * 暂存离线消息
     */
    public void cacheMessagePut(String userId, String message) {
        String key = WEB_SOCKET_KEY + userId;
        if (StringUtils.isNotEmpty(message)) {
            RedisUtil.redis.opsForList().rightPush(key, message);
            log.info(WEB_SOCKET_KEY + userId + "消息暂存成功");
        }
    }


}

package com.demo.config.websocket;

import cn.hutool.json.JSONObject;
import jakarta.annotation.Resource;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;

/**
 * @class：WebSocketController
 * @since: 2023/9/20 9:01
 * @description:
 */
@RestController
@RequestMapping("/websocket")
public class WebSocketController {

    @Resource
    private WebSocket webSocket;

    @RequestMapping("/send/{userId}")
    public void send(@PathVariable String userId){
//全体发送
//        WebSocket.sendAllMessage("消息来了3333333333333333");
//单个用户发送 (userId为用户id)
        webSocket.sendOneMessage(userId, "消息来了2222222222222");
//多个用户发送 (userIds为多个用户id，逗号‘,’分隔)
//        webSocket.sendMoreMessage(userIds, obj.toJSONString());

    }

}

RedisUtil-防止RedisTemplate报空指针

package com.demo.config.redis;

import com.alibaba.fastjson.JSON;
import jakarta.annotation.PostConstruct;
import jakarta.annotation.Resource;
import lombok.Data;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.scheduling.annotation.Async;
import org.springframework.scheduling.annotation.Scheduled;
import org.springframework.stereotype.Component;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.Optional;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.TimeUnit;

/**
 * redis配置项
 */
@Slf4j
@Component
public class RedisUtil {
    @Resource
    private RedisTemplate redisTemplate;
    //------------------websock------------------------

    //2.添加静态的变量
    public static RedisTemplate redis;

    @PostConstruct
    public void getRedisTemplate(){
        redis=this.redisTemplate;
    }
    //------------------websock------------------------

}

成功示例

注意：

1、nginx配置需要加入指定配置

proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";

2、加入的服务一定注意只存在一个容器

tomcat/undertow/其他：如果存在多个会导致方法的实现类过多找不到对应的使用方法，websocket容器加载为null。
如果使用undertow容器则需要排除spring-boot-start-web自带的tomcat容器

如果仍然解决不了则需要排查是否存在其余功能引入了tomcat，最简单的则是单独起websocket