Spring Data JPA

Spring Data 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库的访问和操作

 

JPA中的主键生成策略

JPA提供的四种标准用法为TABLE,SEQUENCE,IDENTITY,AUTO。

IDENTITY:主键由数据库自动生成（主要是自动增长型）

用法：

@Id       @GeneratedValue(strategy = GenerationType.IDENTITY)     private Long custId;

 

SEQUENCE：根据底层数据库的序列来生成主键，条件是数据库支持序列。

用法：

@Id       @GeneratedValue(strategy = GenerationType.SEQUENCE,generator="payablemoney_seq")       @SequenceGenerator(name="payablemoney_seq", sequenceName="seq_payment")   private Long custId;

 

AUTO：主键由程序控制

用法：

@Id       @GeneratedValue(strategy = GenerationType.AUTO)       private Long custId;

 

TABLE：使用一个特定的数据库表格来保存主键

用法：

@Id       @GeneratedValue(strategy = GenerationType.TABLE, generator="payablemoney_gen")       @TableGenerator(name = "pk_gen",           table="tb_generator",           pkColumnName="gen_name",           valueColumnName="gen_value",           pkColumnValue="PAYABLEMOENY_PK",           allocationSize=1       ) private Long custId;

 

使用SQL语句查询

Spring Data JPA同样也支持sql语句的查询，如下：

/**      * nativeQuery : 使用本地sql的方式查询      */     @Query(value="select * from cst_customer",nativeQuery=true)     public void findSql();

方法命名规则查询

按照Spring Data JPA 定义的规则，查询方法以findBy开头，涉及条件查询时，条件的属性用条件关键字连接，要注意的是：条件属性首字母需大写。框架在进行方法名解析时，会先把方法名多余的前缀截取掉，然后对剩下部分进行解析。

//方法命名方式查询（根据客户名称查询客户）     public Customer findByCustName(String custName);

 

具体的关键字，使用方法和生产成SQL如下表所示

 

Keyword	Sample	JPQL
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)