jpa(1)

SPring Data JPA 提供的编程接口：

• Repository ： 最顶层的接口，是一个空接口，目的是为了统一所有的 Repository 的类型，且能让组件扫描的时候自动识别。
• CrudRepository： Repository 的子接口，提供CRUD的功能
• PageingAndSortingRepository ： CrudRepository 的子接口，添加分页排序的功能
• JpaRepository ： PageingAndSortingRepository 的子接口，增加批量操作等功能
• JpaSpecificationExecutor ： 用来做复杂查询的接口

JpaRepository 接口方法：

• delete 删除或者批量删除
• findAll 查找所有
• findOne 查找单个
• save 保存单个或批量保存

• saveAndFlush 保存并保存到数据库

  示例：用户管理

  persitent.xml 配置文件

   <?xml version="1.0" encoding="UTF-8"?>
  <persistence xmlns="http://java.sun.com/xml/ns/persistence" version="1.0">
  <persistence-unit name="userPU" transaction-type="RESOURCE_LOCAL">
      <!--jpa的提供者-->
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <properties>
          <!--声明数据库连接的驱动-->
          <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/>
          <!--jdbc数据库的连接地址-->
          <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/test?characterEncoding=UTF-8&amp;autoReconnect=true"/>
          <property name="hibernate.connection.username" value="root"/>
          <property name="hibernate.connection.password" value="zdw890926"/>
          <!--配置方言-->
          <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/>
          <!--激活查询日志功能-->
          <property name="hibernate.show_sql" value="true"/>
          <!--优雅地输出Sql-->
          <property name="hibernate.format_sql" value="true"/>
          <!--添加一条解释型标注-->
          <property name="hibernate.use_sql_comments" value="false"/>
          <!--配置如何根据java模型生成数据库表结构,常用update,validate-->
          <property name="hibernate.hbm2ddl.auto" value="update"/>
      </properties>
  </persistence-unit>
  </persistence>

Spring 上下文的配置文件 applicationContext.xml 文件：

 <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
    xmlns:context="http://www.springframework.org/schema/context"   
    xmlns:jdbc="http://www.springframework.org/schema/jdbc"    
    xmlns:jee="http://www.springframework.org/schema/jee"   
    xmlns:tx="http://www.springframework.org/schema/tx"  
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"  
    xsi:schemaLocation="  
        http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd  
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd  
        http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd  
        http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd  
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd  
        http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd"  
    default-lazy-init="true">

    <!--第一步-->
    <!--定义服务层代码存放的包扫描路径-->
	<context:component-scan base-package="javaskills.jpa.usermanage.service" />

    <!--第二步-->
    <!--定义实体的工厂bean-->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="persistenceUnitName" value="userPU" />
        <property name="persistenceXmlLocation" value="classpath:persistent.xml"></property>
    </bean>

    <!--第三步-->
    <!--定义事务管理器-->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

    <!--第四步-->
    <!--定义repository接口的存放目录-->
    <!--定义接口实现的后缀，通常用Impl-->
    <!--定义实体工厂的引用-->
    <!--定义事务管理器的引用-->
   	<jpa:repositories base-package="javaskills.jpa.usermanage.repository"
   					  repository-impl-postfix="Impl" 
   					  entity-manager-factory-ref="entityManagerFactory" 
   					  transaction-manager-ref="transactionManager"/>
    <!--第五步-->
    <!--声明采用注解的方式申明事务-->
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>

查询操作的基本实现 — 方法名构造方法

find + 全局修饰 + By + 实体的属性名称 + 限定词 + 连接词 + ... （其他实体属性）+ OrderBy + 排序属性 + 排序方向

例如
findDistinctByFirstNameIgnoreCaseAndLastNameOrderByAgeDesc(String firstName,String lastName)

其中：
Distinct 是全局修饰 非必须
FirstName 和 LastName 是实体的属性名
And 是连接词
IgnoreCase 是限定词
Age 是排序属性
Desc 是排序方向
限定词和连接词统称为“关键词”

关键词分类：
全局修饰： Distinct , Top , First
关键词： IsNull,IsNotNull,Like,NotLike,Containing,In,NotIn,IgnoreCase,Between,Equals,LessThan,GreaterThan,After,Before……
排序方向：Asc,Desc
连接词：And,Or

Table 2.3. Supported keywords inside method names

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	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<Age> ages)	… where x.age in ?1
NotIn	findByAgeNotIn(Collection<Age> 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

@Entity
@Table(name = "user")
public class User {

    @Id
    @GeneratedValue
    private Integer id;
    private String name;
    private String address;
    private String phone;
    //省略getter和setter
}