<script>
  const eventSource = new EventSource('/sse/stream');

  eventSource.onmessage = function(event) {
    console.log('收到消息：', event.data);
    // 可更新到页面上
  };

  eventSource.onerror = function(err) {
    console.error('连接出错', err);
    // 可以展示连接断开的提示
  };
</script>

@RestController
publicclass SseController {
    privatestaticfinal Map<String, SseEmitter> emitters = new ConcurrentHashMap<>();

    // 浏览器连接入口
    @GetMapping("/sse-connect")
    public SseEmitter connect(@RequestParam String userId) {
        SseEmitter emitter = new SseEmitter(30 * 60 * 1000L); // 30分钟超时
        emitters.put(userId, emitter);

        // 发送欢迎消息
        try {
            emitter.send(SseEmitter.event()
                    .name("welcome")
                    .data("&#127881; 连接成功！欢迎使用 SSE 服务"));
        } catch (IOException e) {
            System.err.println("发送欢迎消息失败: " + e.getMessage());
        }

        emitter.onCompletion(() -> emitters.remove(userId));
        emitter.onTimeout(() -> emitters.remove(userId));

        return emitter;
    }

    // 模拟推送服务
    @Scheduled(fixedRate = 2000)
    public void pushData() {
        emitters.forEach((userId, emitter) -> {
            try {
                String json = String.format(
                        "{\"time\": \"%s\", \"value\": %.2f}",
                        LocalTime.now(), Math.random() * 100
                );

                // 构建符合SSE格式的消息
                emitter.send(SseEmitter.event()
                        .id(UUID.randomUUID().toString())
                        .name("system-metrics")
                        .data(json));
            } catch (IOException e) {
                emitters.remove(userId);
            }
        });
    }
}

curl --location 'localhost:18500/sse-connect?userId=1' \
--header 'Key: Accept' \
--header 'Value: text/event-stream'