当前位置 博文首页 > 逐墨飞扬的博客：Spring Boot Jpa
Spring Boot Jpa 是 Spring 基于 ORM 框架、Jpa 规范的基础上封装的一套 Jpa 应用框架，可使开发者用极简的代码即可实现对数据的访问和操作。它提供了包括增删改查等在内的常用功能，且易于扩展！学习并使用 Spring Data Jpa 可以极大提高开发效率！
Spring Boot Jpa 让我们解脱了 DAO 层的操作，基本上所有 CRUD 都可以依赖于它来实现
具体的关键字，使用方法和生产成SQL如下表所示
| 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) |
<!-- SpringBoot JPA依赖 -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
/**
* 使用Spring Data JPA操作数据库，实体类上需要加@Entity注解、主键属性上需要加@Id注解
*/
@Entity //@Entity注解是JPA里提供的注解，标注此类是一个实体类
@Getter
@Setter
public class Message {
@Id
private Integer id;
// 这里如果用apache的dbutils查询的话，字段名称必须和数据库中完全一样。否则结果集封装不进来
// 此时需要添加一个注解 @Column
private Integer fromId;
private Integer toId;
private String subject;
private String content;
private Date createtime;
private Integer status;
private String attachment;
@Override
public String toString() {
return "Message{" +
"id=" + id +
", fromId=" + fromId +
", toId=" + toId +
", subject='" + subject + '\'' +
", content='" + content + '\'' +
", createtime=" + createtime +
", status=" + status +
", attachment='" + attachment + '\'' +
'}';
}
}
public interface MessageDao extends JpaRepository<Message,Integer> {
//按 status 字段查询
List<Message> findMessageByStatus(Integer status);
// @Transactional注解必须加到update、save、delete这些修改数据操作上（否则会报没有可用事务异常）
@Transactional
// 下面这俩注解是一组，适合于自定义SQL语句时配合使用
@Query("delete from Message where id = ?1")
@Modifying //如果语句是要修改数据库必须添加@Modifying注解
void deleteById(Integer id);
}
@RunWith(SpringRunner.class)
@SpringBootTest
public class TestJpa {
@Autowired
private MessageDao messageDao;
/**
* 调用Spring JPA 原生findAll方法
*/
@Test
public void testFindAll() {
List<Message> messageList = messageDao.findAll();
for(Message message : messageList){
System.out.println(message);
}
}
/**
* 调用自定义的查询方法，按照status字段查询
*/
@Test
public void testFindMessageByStatus(){
List<Message> messageList = messageDao.findMessageByStatus(2);
for(Message message : messageList){
System.out.println(message);
}
}
/**
* 调用Spring JPA原生saveAndFlush修改数据
* 注:在修改数据库某个字段的同时,数据库其他字段的值会被清空
*/
@Test
public void testUpdateMessage() {
Message message = new Message();
message.setId(10);
message.setContent("秦羽");
messageDao.saveAndFlush(message);
}
/**
* 调用自定义语句完成删除操作,按照status字段删除
*/
@Test
public void testDeleteMessageById() {
messageDao.deleteById(9);
}
}
更多jpa的应用请点击此处查阅
cs