SpringJpa学习教程-02根据关键字查询
常用的接口继承类
Repository:无任何方法
CrudRepository:具有简单的一些增删改查的方法
PageAndSortingRepository:具有一些简单的分页查询功能和排序功能
JpaRepository:继承了PagingAndSortingRepository,对它的方法进行了一些扩展,
以下是提供的一些方法,可以看到支持批量更新和删除
<S extends T> List<S> saveAll(Iterable<S> entities);
<S extends T> S saveAndFlush(S entity);
void deleteInBatch(Iterable<T> entities);
自定义查询配置
在JpaApplication中添加注解
@EnableJpaRepositories(queryLookupStrategy = QueryLookupStrategy.Key.CREATE_IF_NOT_FOUND)
解释:
@EnableJpaRepositories表示启用自定义查询
查询策略有三种:
CREATE:直接根据方法名进行创建,如果方法名不符合规则则启动时报错USE_DECLARED_QUERY:注解方式创建CREATE_IF_NOT_FOUND:两种方式的结合,先使用注解扫描,没扫描到,则使用Create创建
自定义查询
我们在UserRepository中添加以下方法,分别是根据姓名查询所有的用户和查询出不带重复姓名的用户列表
List<User> findUsersByName(String name);
List<User> findDistinctByName(String name);
在UserController中添加以下方法
@GetMapping(path = "/byName")
@ResponseBody
public List<User> findByName(@RequestParam(value = "name") String name) {
return userRepository.findUsersByName(name);
}
@GetMapping(path = "/findNameWithDistinct")
@ResponseBody
public List<User> findNameWithDistinct(@RequestParam(value = "name") String name) {
return userRepository.findDistinctByName(name);
}
启动SpringBoot进行访问,可知方法生效了.
关键字列表
| 关键字 | 示例 | JPQL表达式 |
|---|---|---|
| And | findByNameAndEmail | where u.name = ?1 and u.email = ?2 |
| Or | findByNameOrEmail | where u.name = ?1 or u.email = ?2 |
| Is/Equals | findByNameEquals | where u.name = ?1 |
| Between | findByBirthdayBetween | where u.birthday between ?1 and ?2 |
| LessThan | findByAgeLessThan | where x.age < ?1 |
| LessThanEqual | findByAgeLessThanEqual | where x.age <= ?1 |
| GreaterThan | findByAgeGreaterThan | where x.age > ?1 |
| GreaterThanEqual | findByAgeGreaterThanEqual | where x.age >= ?1 |
| After | findByStartDateAfter | where x.startDate > ?1 |
| Before | findByStartDateBefore | where x.startDate < ?1 |
| IsNull | findByNameIsNull | where x.name is null |
| IsNotNull/NotNull | findByNameNotNull | where x.name not null |
| Like | findByNameLike | where x.name like ?1 |
| NotLike | findByNameNotLike | where x.name not like ?1 |
| StartingWith | findByNameStartingWith | where x.name like %?1 |
| EndingWith | findByNameEndingWith | where x.name like ?1% |
| Containing | findByNameContaining | where x.name like %?1% |
| OrderyBy | findByAgeOrderByNameDesc | where x.age = ?1 order by x.name desc |
| Not | findByNameNot | where x.name <> ?1 |
| In/NotIn | findByAgeIn(Collection ages) | where x.age in ?1 |
| True/False | findByActiveTrue | where x.active = true |
| IgnoreCase | findByNameIgnoreCase | where UPPER(x.name) = UPPER(?1) |
以上均为find系列的前缀,与find相同的前缀还有read``get``query``stream
也就是说,findByName=getByName等同
计数系列:count
存在系列:exists
删除系列:delete/remove