[英]Spring Repository nullpointerexception
我正在尝试使用Spring-Boot编写一个非常基本的应用程序。 我目前唯一想做的就是从SQL Server数据库中获取一些信息。
应用程序
@SpringBootApplication(scanBasePackageClasses = { MainView.class, Application.class })
@EnableJpaRepositories(basePackageClasses = CustomerRepository.class)
@EntityScan(basePackageClasses = Customer.class)
public class Application extends SpringBootServletInitializer {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
@Override
protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
return application.sources(Application.class);
}
}
Customerrepository.java
@Repository
public interface CustomerRepository extends JpaRepository<Customer, Integer>
{
}
CustomerController.java
@Controller
@RequestMapping(path = "/customer")
public class CustomerController {
@Autowired
private CustomerRepository customerRepository;
@GetMapping(path = "/all")
public @ResponseBody Iterable<Customer> getAllCustomers() {
return customerRepository.findAll();
}
}
客户视图
@Tag("customers-view")
@HtmlImport("src/views/customers/customers-view.html")
@Route(value = ApplicationConst.PAGE_CUSTOMERS, layout = MainView.class)
@PageTitle(ApplicationConst.TITLE_CUSTOMERS)
public class CustomersView extends PolymerTemplate<TemplateModel> {
@Autowired
CustomerRepository customerRepository;
public CustomersView() {
customerRepository.findAll();
}
}
转到http:// localhost:8080 / customer可以很好地返回数据库中的每个客户。
但是,当我尝试在我的CustomerView.java中找到所有客户时,自动装配的CustomerRepository返回一个nullpointerexception。
有人可以指出我正确的方向吗?
尝试使用@Autowire构造函数中的存储库,如下所示:
@Tag("customers-view")
@HtmlImport("src/views/customers/customers-view.html")
@Route(value = ApplicationConst.PAGE_CUSTOMERS, layout = MainView.class)
@PageTitle(ApplicationConst.TITLE_CUSTOMERS)
public class CustomersView extends PolymerTemplate<TemplateModel> {
CustomerRepository customerRepository;
@Autowired
public CustomersView(CustomerRepository customerRepository) {
this.costumerRepository = customerRepository;
this.customerRepository.findAll();
}
}
发生这种情况是因为在构造函数完成后会插入所有@autowired属性。 如果要在构造函数时注入@autowired属性,则必须使用上面的方法。
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