springboot实现websocket_spring-boot-starter-websocket

1、maven依赖

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

<dependency>
    <groupId>log4j</groupId>
    <artifactId>log4j</artifactId>
    <version>1.2.17</version>
</dependency>

<dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
</dependency>

<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>fastjson</artifactId>
    <version>1.2.73</version>
</dependency>

2、新建 WebSocketStompConfig 类

/**
 * 开启WebSocket支持
 */
@Configuration
public class WebSocketStompConfig {
    @Bean
    public ServerEndpointExporter serverEndpointExporter()
    {
        return new ServerEndpointExporter();
    }
 
}

 3、新建 WebSocket 类

/**
 * WebSocketServer
 */
@Component
@ServerEndpoint("/websocket/{username}")
@Log4j2
public class WebSocket {
    private Logger logger = LoggerFactory.getLogger(this.getClass());
 
    /**
     * 在线人数
     */
    public static int onlineNumber = 0;
    /**
     * 以用户的姓名为key，WebSocket为对象保存起来
     */
    private static Map<String, WebSocket> clients = new ConcurrentHashMap<String, WebSocket>();
    /**
     * 会话
     */
    private Session session;
    /**
     * 用户名称
     */
    private String username;
 
    /**
     * 建立连接
     *
     * @param session
     */
    @OnOpen
    public void onOpen(@PathParam("username") String username, Session session) {
        onlineNumber++;
        logger.info("现在来连接的客户id：" + session.getId() + "用户名：" + username);
        this.username = username;
        this.session = session;
        logger.info("有新连接加入！ 当前在线人数" + onlineNumber);
        try {
            //messageType 1代表上线 2代表下线 3代表在线名单 4代表普通消息
            //先给所有人发送通知，说我上线了
            Map<String, Object> map1 = new HashMap<>();
            map1.put("messageType", 1);
            map1.put("username", username);
            sendMessageAll(JSON.toJSONString(map1), username);
 
            //把自己的信息加入到map当中去
            clients.put(username, this);
            //给自己发一条消息：告诉自己现在都有谁在线
            Map<String, Object> map2 =new HashMap<>();
            map2.put("messageType", 3);
            //移除掉自己
            Set<String> set = clients.keySet();
            map2.put("onlineUsers", set);
            sendMessageTo(JSON.toJSONString(map2), username);
        } catch (IOException e) {
            logger.info(username + "上线的时候通知所有人发生了错误");
        }
 
 
    }
 
    @OnError
    public void onError(Session session, Throwable error) {
        logger.info("服务端发生了错误" + error.getMessage());
        //error.printStackTrace();
    }
 
    /**
     * 连接关闭
     */
    @OnClose
    public void onClose() {
        onlineNumber--;
        //webSockets.remove(this);
        clients.remove(username);
        try {
            //messageType 1代表上线 2代表下线 3代表在线名单  4代表普通消息
            Map<String, Object> map1 = new HashMap<>();
            map1.put("messageType", 2);
            map1.put("onlineUsers", clients.keySet());
            map1.put("username", username);
            sendMessageAll(JSON.toJSONString(map1), username);
        } catch (IOException e) {
            logger.info(username + "下线的时候通知所有人发生了错误");
        }
        logger.info("有连接关闭！ 当前在线人数" + onlineNumber);
    }
 
    /**
     * 收到客户端的消息
     *
     * @param message 消息
     * @param session 会话
     */
    @OnMessage
    public void onMessage(String message, Session session) {
        try {
            logger.info("来自客户端消息：" + message + "客户端的id是：" + session.getId());
            JSONObject jsonObject = JSON.parseObject(message);
            String textMessage = jsonObject.getString("message");
            String fromusername = jsonObject.getString("username");
            String tousername = jsonObject.getString("to");
            //如果不是发给所有，那么就发给某一个人
            //messageType 1代表上线 2代表下线 3代表在线名单  4代表普通消息
            Map<String, Object> map1 = new HashMap<>();
            map1.put("messageType", 4);
            map1.put("textMessage", textMessage);
            map1.put("fromusername", fromusername);
            if (tousername.equals("All")) {
                map1.put("tousername", "所有人");
                sendMessageAll(JSON.toJSONString(map1), fromusername);
            } else {
                map1.put("tousername", tousername);
                sendMessageTo(JSON.toJSONString(map1), tousername);
            }
        } catch (Exception e) {
            logger.info("发生了错误了");
        }
 
    }
 
 
    public void sendMessageTo(String message, String ToUserName) throws IOException {
        for (WebSocket item : clients.values()) {
            if (item.username.equals(ToUserName)) {
                item.session.getAsyncRemote().sendText(message);
                break;
            }
        }
    }
 
    public void sendMessageAll(String message, String FromUserName) throws IOException {
        for (WebSocket item : clients.values()) {
            item.session.getAsyncRemote().sendText(message);
        }
    }
 
    public static synchronized int getOnlineCount() {
        return onlineNumber;
    }
}

4、前端访问地址 ws://地址/用户名

5、发送信息格  （to = All：所有人）

{

    "message": "消息内容",

    "to": "All", 

    "username": "发送人名称"

}