WebSocket 使用

注意

1. 浏览器地址栏不能直接发起websocket请求,需要通过接口工具或者写页面
2. 发起请求协议为ws

使用 WebSocket

1.业务类

用于写WebSocket连接和关闭的业务代码

@Slf4j
@Component
public class WSServicer implements WebSocketHandler {

    //当前操作图片的用户，这里设定只能一个用户进行操作
    public static Map<Long, Long> pictureHandleUsersMap = new ConcurrentHashMap<>();

    //建立连接的所有图片session会话集合
    public static Map<Long, Set<WebSocketSession>> sessionMap = new ConcurrentHashMap<>();


    //建立连接后,把session会话连接放到map中
    @Override
    public void afterConnectionEstablished(WebSocketSession session) throws Exception {

        String requestUri = String.valueOf(session.getUri());
        String imageId = requestUri.substring(requestUri.lastIndexOf("/") + 1);
        Long picId = Long.valueOf(imageId);

        //初始化一个set集合
        sessionMap.putIfAbsent(picId, ConcurrentHashMap.newKeySet());

        // 将当前会话添加到该图片ID的会话集合中
        Set<WebSocketSession> sessions = sessionMap.get(picId);
        sessions.add(session);

        boad(picId);
    }


    //连接关闭，移除关闭连接的session
    @Override
    public void afterConnectionClosed(WebSocketSession session, CloseStatus closeStatus) throws Exception {
        sessionMap.remove(session.getId());
        log.info("该会话关闭连接{}", session.getId());
    }



    //自定义广播方法, 给当前图片的连接用户广播信息
    public static void boad(Long piutureId) throws IOException {
        Set<WebSocketSession> sessions = sessionMap.get(piutureId);
        sessionMap.putIfAbsent(piutureId, ConcurrentHashMap.newKeySet());
        String strId = String.valueOf(piutureId);
        for (WebSocketSession session : sessions) {
            session.sendMessage(new TextMessage(String.format("你是正在处理图片%s的用户", strId)));
        }

    }

}

2.WebSocket拦截器

1. WebSocket 的握手阶段本质上就是一次普通的 HTTP 请求

2. 所以在握手阶段（beforeHandshake 方法里），可以把ServerHttpRequest 转成 HttpServletRequest，就像处理http请求一样去拦截鉴权：

@Component
public class WsInterceptor implements HandshakeInterceptor  {
 @Override
    public boolean beforeHandshake(ServerHttpRequest request, ServerHttpResponse response, WebSocketHandler wsHandler, Map<String, Object> attributes) throws Exception {

        HttpServletRequest httpServletRequest = null;
        HttpServletResponse httpServletResponse = null;
        if (request instanceof ServletServerHttpRequest servletRequest) {
            httpServletRequest = servletRequest.getServletRequest();
        }

        if (response instanceof ServletServerHttpResponse servletResponse) {
            httpServletResponse = servletResponse.getServletResponse();
        }


        //登录鉴权

        //1.拿到请求头中的token
        String token = httpServletRequest.getHeader("Authorization");

        if (token == null) {
            httpServletResponse.setStatus(401);
            throw new CustomerException(410, "用户token不存在");
        }
        Map<String, Object> userMap = JwtUtil.parseToken(token);

        Object idObj = userMap.get("id");
        Long userId;
        if (idObj instanceof Number) {
            userId = ((Number) idObj).longValue();
        } else {
            throw new CustomerException("JWTAuthorization 中的 id 不是有效的数字类型");
        }
        //2.检验是否和redis中的一致
        String redisToken = (String) redisTemplate.opsForValue().get(USER_TOKEN_KEY + userId);

        if (!token.equals(redisToken)) {
            throw new CustomerException(401, "token无效");
        }


        //权限鉴权....等


        //放行
        return true;
    }
}

3.WebSocket 配置类

1. addHandler为配置注册处理器，参数为业务处理类和请求路径
2. addInterceptors 为WebSocket拦截器，握手建立之前进行拦截。类似于 HTTP 请求的前置拦截器。

@Configuration
@EnableWebSocket
public class WsConfig implements WebSocketConfigurer{

    @Autowired
    WSServicer wsServicer;

    @Autowired
    WsInterceptor  WsInterceptor

    // WebSocket 配置
    public void registerWebSocketHandlers(WebSocketHandlerRegistry registry) {
        // WebSocket的注册处理器和拦截处理器
        registry.addHandler(wsServicer, "/test/{id}") //注册处理器
                .addInterceptors(WsInterceptor)  // 自定义拦截器
                .setAllowedOrigins("*");  // 允许跨域
    }

}

WebSocket 扩展玩法

通过发送http请求给ws连接发布消息

//新玩法，通过请求给ws的连接发送消息
@RestController
public class WebSocketController {

    // 通过 API 触发向处理图片1的所有用户发送消息
    @GetMapping("/sendMessage")
    public String sendMessage(@RequestParam Long pictureId) throws IOException {
        // 调用 WebSocket 服务的广播方法
        WSServicer.boad(pictureId);
        return "消息已发送给所有处理图片" + pictureId + "的用户";
    }
}