spring-data

1. spring-data是spring提供的数据访问层框架，封装若干种数据服务访问能力。

   spring-data-jpa：通过JPA标准规范，底层使用Hibernate框架实现。
   spring-data-jdbc：就是底层使用spring-jdbc实现，可以使用Mybatis技术作为底层实现的替代产品。
   spring-data-redis：底层使用jedis实现。 

2. spring-data-JPA

   1. 类图
   2. Repository标记接口。可以继承此接口，根据指定的规则，实现数据查询。只能做单表查询，且查询结果一定是实体类型对象或实体类型对象的集合。命名规则：findBy(关键字)+属性名称(属性名称的首字母大写)+查询条件(首字母大写)

      关键字	方法命名	sql where字句
      And	findByNameAndPwd	where name= ? and pwd =?
      Or	findByNameOrSex	where name= ? or sex=?
      Is,Equal	findById,findByIdEquals	where id= ?
      Between	findByIdBetween	where id between ? and ?
      LessThan	findByIdLessThan	where id < ?
      LessThanEqual	findByIdLessThanEquals	where id <= ?
      GreaterThan	findByIdGreaterThan	where id > ?
      GreaterThanEqual	findByIdGreaterThanEquals	where id > = ?
      After	findByIdAfter	where id > ?
      Before	findByIdBefore	where id < ?
      IsNull	findByNameIsNull	where name is null
      isNotNull,NotNull	findByNameNotNull	where name is not null
      Like	findByNameLike	where name like ?
      NotLike	findByNameNotLike	where name not like ?
      StartingWith	findByNameStartingWith	where name like '?%'
      EndingWith	findByNameEndingWith	where name like '%?'
      Containing	findByNameContaining	where name like '%?%'
      OrderBy	findByIdOrderByXDesc	where id=? order by x desc
      Not	findByNameNot	where name <> ?
      In	findByIdIn(Collection<?> c)	where id in (?)
      NotIn	findByIdNotIn(Collection<?> c)	where id not  in (?)
      True	findByAaaTue	where aaa = true
      False	findByAaaFalse	where aaa = false
      IgnoreCase	findByNameIgnoreCase	where UPPER(name)=UPPER(?)