使用Spring-data-jpa简化数据访问层

一 start

    自定义接口extends JpaRepository<,>其中已经内置了常用的增删改查和分页

    或者继承BaseRepository

@NoRepositoryBean
public interface BaseRepository extends PagingAndSortingRepository,JpaSpecificationExecutor{

}

二 使用

And	findByLastnameAndFirstname	… where x.lastname = ?1 and x.firstname = ?2
Or	findByLastnameOrFirstname	… where x.lastname = ?1 or x.firstname = ?2
Is,Equals	findByFirstname,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)

三 配置集成

    gradle

    compile('org.springframework.boot:spring-boot-starter-data-jpa')

    maven

    
        org.springframework.boot
        spring-boot-starter-data-jpa
   

    // 添加 MySQL或者Oracle连接驱动的依赖

    // 添加druid

    com.alibaba
    druid
    1.1.5

    application.properties

 #DataSource 
 #MySQl
spring.datasource.url=jdbc:mysql://localhost:3306/blog?characterEncoding=utf-8&useSSL=false&serverTimezone=UTC 
spring.datasource.username=root
spring.datasource.password=123456
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
 #Oracle
spring.datasource.type = com.alibaba.druid.pool.DruidDataSource 
spring.datasource.url = jdbc:oracle:thin:@127.0.0.1/orcl 
spring.datasource.username = root 
spring.datasource.password = 123456 
spring.datasource.driver-class-name = oracle.jdbc.driver.OracleDriver

# JPA
spring.jpa.show-sql = true
spring.jpa.hibernate.ddl-auto=create-drop    
        create----每次运行该程序，没有表格会新建表格，表内有数据会清空

        create-drop----每次程序结束的时候会清空表

        update----每次运行程序，没有表格会新建表格，表内有数据不清空，只会更新

        validate----运行程序会校验数据与数据库的字段类型是否相同，不同会报错

 

四 资料

    JPA总结——实体关系映射（一对多@OneToMany）

    https://blog.csdn.net/caiyanzhi123/article/details/50828187

    级联问题

https://blog.csdn.net/u013798111/article/details/23676457

四 问题

    SpringBoot开发项目，引入JPA找不到findOne方法

    (可以使用 repository.findById(id).get();)

    详情看https://blog.csdn.net/pk972703678/article/details/79512417