java - Spring Boot 中的 CrudRespository 方法在哪里实现？

Question

我是 Spring Boot 新手，我发现应用程序类使用了 CrudRepository 接口(interface)。我看到调用了 CrudRepository 接口(interface)中的 .save() 方法，但我不明白该方法是在哪里实现的。 Spring 后端是否会发生这种情况？

这是应用程序类:

@SpringBootApplication
public class Application {

    private static final Logger log = LoggerFactory.getLogger(Application.class);

    public static void main(String[] args) {
        SpringApplication.run(Application.class);
    }

    @Bean
    public CommandLineRunner demo(CustomerRepository repository) {
        return (args) -> {
            // save a couple of customers
            repository.save(new Customer("Jack", "Bauer"));
            repository.save(new Customer("Chloe", "O'Brian"));
            repository.save(new Customer("Kim", "Bauer"));
            repository.save(new Customer("David", "Palmer"));
            repository.save(new Customer("Michelle", "Dessler"));

            // fetch all customers
            log.info("Customers found with findAll():");
            log.info("-------------------------------");
            for (Customer customer : repository.findAll()) {
                log.info(customer.toString());
            }
            log.info("");

            // fetch an individual customer by ID
            repository.findById(1L)
                .ifPresent(customer -> {
                    log.info("Customer found with findById(1L):");
                    log.info("--------------------------------");
                    log.info(customer.toString());
                    log.info("");
                });

            // fetch customers by last name
            log.info("Customer found with findByLastName('Bauer'):");
            log.info("--------------------------------------------");
            repository.findByLastName("Bauer").forEach(bauer -> {
                log.info(bauer.toString());
            });
            // for (Customer bauer : repository.findByLastName("Bauer")) {
            //  log.info(bauer.toString());
            // }
            log.info("");
        };
    }

}

CustomerRepository 扩展了 CrudRepository:

public interface CustomerRepository extends CrudRepository<Customer, Long> {

    List<Customer> findByLastName(String lastName);
}

Answer 1

根据已回答此问题的位置 Chan Chan :

JpaRepository 扩展了 PagingAndSortingRepository，而 PagingAndSortingRepository 又扩展了 CrudRepository。

它们的主要功能是:

CrudRepository mainly provides CRUD functions.

PagingAndSortingRepository provides methods to do pagination and sorting records.

JpaRepository provides some JPA-related methods such as flushing the persistence context and deleting records in a batch.

这是我当前项目中的一个示例，我在其中实现了 CrudRepository、PagingAndSortingRepository 和 JpaRepository。所以当你只需要CRUD功能时，你就实现它。当您需要分页和 CRUD 时。您可以选择PagingAndSortingRepository。然后，当您需要更多功能时，JpaRepository 适合您，

public interface CartRepository extends CrudRepository<ShoppingCart, Integer> {

    @Query("select max(s.itemId) FROM ShoppingCart s")
    public Integer findMaxItemId();

    public List<ShoppingCart> findByCartId(String cartId);

    public ShoppingCart findByItemId(int itemId);
}


public interface ProductRepository extends PagingAndSortingRepository<Product, Integer> {

    @Query(value = "select p from Product p where p.description = SUBSTRING(p.description, 1,:description_length)")
    List<Product> getAll(@Param("description_length")Integer description_length, Pageable pageable);
}


@RepositoryRestResource
public interface AttributesRepository extends JpaRepository<Attribute, Integer> {

    @Query("select new com.turing.ecommerce.DTO.AttributeDTO(a.attributeId, a.name)"
        + " from Attribute a ")
    List<AttributeDTO> findAllAttributes();
}