springboot系列08：jpa的高级使用

自定义高级查询

用一些加一些关键字And 、 Or

接口中定义

/**
 * 用户名或邮箱查询
 */
List<User> findByUserNameOrEmail(String username, String email);

测试类

@Test
public void testFindByUserNameOrEmail(){
    Assert.assertEquals(2,userRepository.findByUserNameOrEmail("zhangl1", "1796969389@qq.com").size());
}

同理：修改、删除、统计语法类似

/**
 *根据主键删除
 */
void deleteById(Long id);

测试结果

@Test
public void testDeleteById(){
    userRepository.deleteById(11L);
    Assert.assertFalse(userRepository.findById(11L).isPresent());
}

基本上 SQL 体系中的关键词都可以使用，例如： LIKE 、 IgnoreCase、 OrderBy

/**
  * 邮箱模糊查询
  */
 List<User> findByEmailLike(String email);

@Test
public void testFindByEmailLike(){
    Assert.assertEquals(2,userRepository.findByEmailLike("%1796969389%").size());
}

Keyword	Sample	JPQL snippet
And	findByLastnameAndFirstname	… where x.lastname = ?1 and x.firstname = ?2
Or	findByLastnameOrFirstname	… where x.lastname = ?1 or x.firstname = ?2
Is,Equals	findByFirstnameIs,findByFirstnameEquals	… where x.firstname = ?1
Between	findByStartDateBetween	… where x.startDate 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	findByAgeIsNull	… where x.age is null
IsNotNull,NotNull	findByAge(Is)NotNull	… where x.age not null
Like	findByFirstnameLike	… where x.firstname like ?1
NotLike	findByFirstnameNotLike	… where x.firstname not like ?1
StartingWith	findByFirstnameStartingWith	… where x.firstname like ?1 (parameter bound with appended %)
EndingWith	findByFirstnameEndingWith	… where x.firstname like ?1 (parameter bound with prepended %)
Containing	findByFirstnameContaining	… where x.firstname like ?1 (parameter bound wrapped in %)
OrderBy	findByAgeOrderByLastnameDesc	… where x.age = ?1 order by x.lastname desc
Not	findByLastnameNot	… where x.lastname <> ?1
In	findByAgeIn(Collection ages)	… where x.age in ?1
NotIn	findByAgeNotIn(Collection age)	… where x.age not in ?1
TRUE	findByActiveTrue()	… where x.active = true
FALSE	findByActiveFalse()	… where x.active = false
IgnoreCase	findByFirstnameIgnoreCase	… where UPPER(x.firstame) = UPPER(?1)

分页查询

SpringBoot Jpa 已经帮我们实现了分页的功能，在查询的方法中，需要传入参数Pageable

@Test
public void testFindAllByPage(){
    Pageable pageable = PageRequest.of(0, 10, new Sort(Sort.Direction.DESC, "id"));
    Assert.assertEquals(2,userRepository.findAll(pageable).getTotalElements()); 
}

限制查询

有时候我们只需要查询前N个元素，或者取前一个实体

/**
 * 取前10条数据
 */
Page<User> queryFirst10ByUserName(String userName, Pageable pageable);

测试

@Test
public void testQueryFirst10ByUserName(){
    Pageable pageable = PageRequest.of(0, 10, new Sort(Sort.Direction.DESC, "id"));
    Page<User> userPage = userRepository.queryFirst10ByUserName("zhangl1", pageable);
    Assert.assertEquals(1,userRepository.queryFirst10ByUserName("zhangl1", pageable).getSize() );
}