SpringDdata JPA 重要功能和demo 实现

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目录

概 述

方案设计

1.JPA 实现基本的CRUDP

这个比较简单

2.JPA实现复杂的查询
findAll()方法
findAll中的方法List<> findAll(Example<> example, Sort sort)，此方法用于多条件查询以及排序
Example<> 封装对象到Example，Sort sort是排序条件，

public BusinessIndex findByCode(Long cityCode,Long disCode){
//log.info(cityCode.toString()+“,”+disCode.toString());
BusinessIndex businessIndex = new BusinessIndex();
businessIndex.setCityCode(cityCode);
businessIndex.setDisCode(disCode);
log.info(businessIndex.toString());
Example a = Example.of(businessIndex);
Sort sort =Sort.by(Sort.Direction.DESC,“DateOfValue”);
List all = businessIndexRepository.findAll(a,sort);
return all.get(0);
}

在JPA的repository或者dao中写sql语句

public interface BusinessIndexRepository extends JpaRepository<BusinessIndex,Long> {

@Query(nativeQuery=true, value ="select * from businessIndex c where c.cityCode=:cityCode and c.disCode=:disCode order by DateOfValue DESC limit 1")
BusinessIndex findByCode(@Param("cityCode") Long cityCode,@Param("disCode") Long disCode);

}
其他的有效工具见组件分析模块

小结

参考资料和推荐阅读

1.链接: 参考资料.

2.链接: 参考资料.

3.SpringDataJPA 英文: 参考资料.

4.https://spring.io/guides/gs/accessing-data-jpa/