DeferredResult长轮询

// 存放监听某个Id的长轮询集合
// 线程同步结构
public static Multimap<String, DeferredResult<String>> watchRequests = Multimaps.synchronizedMultimap(HashMultimap.create());


@GetMapping(path = "watch/{id}")
@ResponseBody
public DeferredResult<String> watch(@PathVariable String id) {
    // 延迟对象设置超时时间
    DeferredResult<String> deferredResult = new DeferredResult<>(10000L);
    // 异步请求完成时移除 key，防止内存溢出
    deferredResult.onCompletion(() -> {
        watchRequests.remove(id, deferredResult);
    });
    deferredResult.onTimeout(() -> {
        deferredResult.setResult("超时");
    });
    // 注册长轮询请求
    watchRequests.put(id, deferredResult);
    return deferredResult;
}

@GetMapping(path = "publish/{id}")
@ResponseBody
public String publish(@PathVariable String id) {
    if (watchRequests.containsKey(id)) {
        Collection<DeferredResult<String>> deferredResults = watchRequests.get(id);
        for (DeferredResult<String> deferredResult : deferredResults) {
            deferredResult.setResult("我更新了" + new Date());
        }
    }
    return "success";
}