相关疑难解决方法(0)

注意:这是针对常见问题的规范答案.

我有一个Spring @Serviceclass(MileageFeeCalculator),它有一个@Autowiredfield(rateService),但该字段是null我尝试使用它时.日志显示正在创建MileageFeeCalculatorbean和MileageRateServicebean,但NullPointerException每当我尝试mileageCharge在我的服务bean上调用该方法时,我都会得到.为什么Spring没有自动装配领域？

控制器类:

@Controller
public class MileageFeeController {    
    @RequestMapping("/mileage/{miles}")
    @ResponseBody
    public float mileageFee(@PathVariable int miles) {
        MileageFeeCalculator calc = new MileageFeeCalculator();
        return calc.mileageCharge(miles);
    }
}

服务类:

@Service
public class MileageFeeCalculator {

    @Autowired
    private MileageRateService rateService; // <--- should be autowired, is null

    public float mileageCharge(final int miles) {
        return (miles * rateService.ratePerMile()); // <--- throws NPE
    }
}

应该自动装配的服务bean,MileageFeeCalculator但它不是:

@Service …