package org.zgf.spring.data.dao;

import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
import org.zgf.spring.data.entity.StudentPO;

/**
 * JpaRepository 继承于 PagingAndSortingRepository 接口,
 * 由于JpaSpecificationExecutor 并不继承repository 接口，所以它不能单独使用，只能和jpa Repository 一起用
 */
public interface IStudentJpaRepository extends JpaRepository<StudentPO, Integer>, JpaSpecificationExecutor<StudentPO> {/** JpaRepository 主要特点，将返回类型 Iterable 转换成了List， 并新增了写方法
     * List<T> findAll();
     * List<T> findAll(Sort sort);
     * List<T> findAll(Iterable<ID> ids);
     * <S extends T> List<S> save(Iterable<S> entities);
     * void flush();
     * <S extends T> S saveAndFlush(S entity);
     * void deleteInBatch(Iterable<T> entities);
     * void deleteAllInBatch();
     * T getOne(ID id);
     */
    /** JpaSpecificationExecutor 实现了带条件的查询
     *  T findOne(Specification<T>);
     *  List<T> findAll(Specification<T>);
     *  List<T> findAll(Specification<T>, Sort);
     *  List<T> findAll(Specification<T>, Pageable);
     *  long count(Specification<T>);
     */
}

测试类

package org.zgf.spring.data.dao;

import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.data.jpa.domain.Specification;
import org.zgf.spring.data.base.BaseTest;
import org.zgf.spring.data.dao.IStudentJpaRepository;
import org.zgf.spring.data.entity.StudentPO;

import javax.persistence.criteria.CriteriaBuilder;
import javax.persistence.criteria.CriteriaQuery;
import javax.persistence.criteria.Path;
import javax.persistence.criteria.Predicate;
import javax.persistence.criteria.Root;
import java.util.List;

public class Test_IStudentJpaRepository extends BaseTest {@Autowired
    private IStudentJpaRepository studentJpaSpecification;

    @Testpublic void test_findAll() {Specification<StudentPO> specification = new Specification<StudentPO>() {@Override
            public Predicate toPredicate(Root<StudentPO> root, CriteriaQuery<?> query, CriteriaBuilder cb) {Path path = root.get("id");
                Predicate predicate = cb.lt(path, 5);
                return predicate;
            }};
        List<StudentPO> studentList = this.studentJpaSpecification.findAll(specification);
        for (StudentPO studentPO : studentList) {System.out.println(studentPO);
        }}
}