Quartz-当我尝试将实体保存到数据库时{nullpointer

Question

我的代码有问题。 对OpenWeatherMap服务的每个查询都应将温度和日期变量保存到基准中。不幸的是，我的null指针有问题。我在Internet上找到了您无法在数据库的Quartz作业中执行的信息，但是我不知道如何更改此代码。

这是我的石英作业班

@Component
@NoArgsConstructor
public class QuartzJob implements Job {

    private final String prefix = "https://api.openweathermap.org/data/2.5/weather?q=";
    private final String key = "&units=metric&appid=b25d9b1a1e64e5e91ed9d14b74c1ca01";

    @Autowired
    private WeatherModelRepository weatherModelRepository;

    @Autowired
    private CityModelRepository cityModelRepository;


    @Override
    public void execute(JobExecutionContext jobExecutionContext) throws JobExecutionException {

        String cityName = String.valueOf(jobExecutionContext.getJobDetail().getKey()).substring(8);

        String myUrl = prefix+cityName+key;

        Weather weather = new Weather();

        try{

            URL url1 = new URL(myUrl);

            ObjectMapper objectMapper = new ObjectMapper();

            JsonNode jsonRoot = objectMapper.readTree(url1);
            JsonNode jsonMain = jsonRoot.path("main");
            JsonNode jsonTemperature = jsonMain.path("temp");

            Date date = new Date();

            weather.setTemperature(jsonTemperature.asText());
            weather.setTimestamp(new Timestamp(date.getTime()));
            //weather.setCityModel(cityModelRepository.findByCityName(cityName));
            System.out.println(cityName);
            //weatherModelRepository.save(weather);
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

空指针在行中，注释在哪里。您能给我建议如何解决这个问题吗？