首先，你好。我有員工、地點、部門和工作類別。每個類都有自己的 JPA Repository 接口。我有一個服務類，我想在這個類中一一創建對象，用控制器調用這個方法并寫入數據庫。但我收到以下錯誤。我該如何修復這個錯誤？我哪里做錯了，如果您能幫忙，我將不勝感激。項目結構在這里服務@Servicepublic class MainService {? ? @Autowired? ? LocationsRepository locationsRepository;? ? @Autowired? ? JobsRepository jobsRepository;? ? @Autowired? ? EmployeesRepository employeesRepository;? ? @Autowired? ? DepartmentsRepository departmentsRepository;? ? public String generateManual() {? ? ? ? try {? ? ? ? ? ? Locations locations = new Locations();? ? ? ? ? ? locations.setCountry("Turkey");? ? ? ? ? ? locations.setCity("Istanbul");? ? ? ? ? ? locationsRepository.save(locations);? ? ? ? ? ? Jobs jobs = new Jobs();? ? ? ? ? ? jobs.setSalary(4000);? ? ? ? ? ? jobs.setTitle("Software Developer");? ? ? ? ? ? jobsRepository.save(jobs);? ? ? ? ? ? Employees employees = new Employees();? ? ? ? ? ? employees.setFirstName("Mutlu");? ? ? ? ? ? employees.setLastName("Eren");? ? ? ? ? ? employees.setJobs(jobs);? ? ? ? ? ? employeesRepository.save(employees);? ? ? ? ? ? Departments departments = new Departments();? ? ? ? ? ? departments.setName("IT");? ? ? ? ? ? departments.setLocations(locations);? ? ? ? ? ? List<Employees> empList = new ArrayList<>();? ? ? ? ? ? empList.add(employees);? ? ? ? ? ? departments.setEmployees(empList);? ? ? ? ? ? departmentsRepository.save(departments);? ? ? ? ? ? return "SUCCESS.";? ? ? ? }catch(Exception e) {? ? ? ? ? ? e.printStackTrace();? ? ? ? ? ? return "FAILED.";? ? ? ? }? ? }}控制器@RestControllerpublic class MainController {? ? @Autowired? ? MainService mainService;? ? @GetMapping("/generate")? ? public void generate() {? ? ? ? mainService.generateManual();? ? }}資源spring.datasource.url=jdbc:mysql://localhost:3306/companydb?useUnicode=true&characterEncoding=UTF-8&useLegacyDatetimeCode=false&serverTimezone=Turkeyspring.datasource.username=rootspring.datasource.password=