springboot datajpa 简明说明

    public Object lookupDevice(Integer id) {
        return deviceJpa.findById(id).orElse(null);
    }

    public Object updateDevice(Integer id) {
        Optional<Device> optionalDevice = deviceJpa.findById(id);
        if (optionalDevice.isPresent()) {
            Device device=optionalDevice.get();
            device.setSerial("HEHHEHEEH");
            return deviceJpa.save(device);
        }
        return null;
    }