在 JSF 中使用 Autowired 时出现 NullPointerException [重复]

Question

我正在使用 Spring-boot、JSF 和 MyBatis。问题是当我尝试使用 MyBatis 映射器时收到 NullPointerException。 MyBatis 连接工作正常，我已经在 Autowired 的单元测试中对其进行了测试（与我在 Service 类中的操作方式相同）。

这是我的 JSF 控制器：

@ManagedBean
@ViewScoped
public class WeatherView implements Serializable {

    private List<Weather> weathers;

    @ManagedProperty(value = WeatherService.EL_NAME)
    private WeatherService weatherService;

    @PostConstruct
    public void init(){
        setWeathers(this.weatherService.getAll());
    }

    public List<Weather> getWeathers() {
        return this.weathers;
    }

    public void setWeathers(List<Weather> weathers) {
        this.weathers = weathers;
    }

    public void setWeatherService(WeatherService weatherService) {
        this.weatherService = weatherService;
    }

WeatherService.java

@Service(WeatherService.BEAN_NAME)
@ManagedBean(name = WeatherService.BEAN_NAME)
@ApplicationScoped
public class WeatherService {

    public static final String BEAN_NAME = "weatherService";

    public static final String EL_NAME = "#{weatherService}";

    @Autowired
    private WeatherMapper weatherMapper; // <-- This is the MyBatis Mapper

    // The NullPointerExceptions is thrown here
    public List<Weather> getAll(){
        return weatherMapper.getAll();
    }

}

如果我使用 Autowired 注释，为什么 weatherMapper 为空？

Answer 1

你应该检查“weatherMapper”类，我认为查询在那里返回空值。