如何重用Spring Data JpaRepository接口

Question

(Using Java 8)

I have a Spring Data JPA repository interface that I use in my persistence layer. It's in charge of table A.

Here is the code of the interface:

package com.bla.bla.persistence;

import com.bla.bla..EntityA;
import org.springframework.data.domain.Pageable;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Modifying;
import org.springframework.data.jpa.repository.Query;
import org.springframework.transaction.annotation.Transactional;

import java.util.List;

@Transactional
public interface TableAJPARepository extends JpaRepository<EntityA, Long> {

    @Query("select distinct i.username from EntityA i")
    List<Integer> findDistinctUsernames();

    @Modifying
    @Query("update EntityA i set i.firstName = ?3 where i.lastName = ?1 and i.age < ?2")
    int updateEntityA(Integer age, String firstName, String lastName);

    @Query("select i from EntityA i where i.firstName = ?1 and (i.age =?2 or i.lastName =?3)")
    List<EntityA> findByFirstNameAndAgeOrLastName(String firstName, Integer age, String lastName);

    @Query("select DISTINCT(i) from EntityA i, EntityA1 r  where r.bookId=i.id " +
            "and i.firstName=?1 and r.title=?2 and i.lastName=?3 and i.age!=2 and i.age<=?4 " +
            "order by i.firstName Desc, i.age DESC ")
    List<EntityA> findBySomeFields(String firstName, String title, String lastName, Integer age,  Pageable pageable);
    ...
}

Some of the queries join with a helper table A1.

I now have table B which is identical to table A, except for its name. Table B uses table B1 for the joins, which is identical to table A1.

The interface has many methods and I'd hate to duplicate the code.

Id there any way to create an interface that is exactly like TableAJPARepository but deals with table B and B1 instead?

Answer 1

You could consider making a custom repository - note the @NoRepositoryBean annotation -

import org.springframework.data.repository.*;

@NoRepositoryBean
public interface YourRepository<T, ID extends Serializable> extends Repository<T, ID> {
}

The first method shouldnt need @Query since Distinct is a method name option on spring jpa -

List<T> findDistinctUsernames();

Id need to have a think on the update - but you could likely use generics for this