在某些不规范的安卓系统中，会禁止后台刷新，此时只能在前台启动 Service

		
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
            startForegroundService(new Intent(MainActivity.this, MessageQueueService.class));
        } else {
            startService(new Intent(MainActivity.this, MessageQueueService.class));
        }