1.1SpringData JPA概述
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。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！
1.2Spring Data JPA 与 JPA和hibernate之间的关系
JPA是一套规范，内部是有接口和抽象类组成的。hibernate是一套成熟的ORM框架，而且Hibernate实现了JPA规范，所以也可以称hibernate为JPA的一种实现方式，我们使用JPA的API编程，意味着站在更高的角度上看待问题（面向接口编程）
2.1 Spring Data JPA的快速入门
2.2 引入Spring Data JPA的坐标
使用Spring Data JPA，需要整合Spring与Spring Data JPA，并且需要提供JPA的服务提供者hibernate，所以需要导入spring相关坐标，hibernate坐标，数据库驱动坐标等
<properties>
<spring.version>5.0.2.RELEASEspring.version>
<hibernate.version>5.0.7.Finalhibernate.version>
<slf4j.version>1.6.6slf4j.version>
<log4j.version>1.2.12log4j.version>
<c3p0.version>0.9.1.2c3p0.version>
<mysql.version>5.1.6mysql.version>
properties>
<dependencies>
<dependency>
<groupId>junitgroupId>
<artifactId>junitartifactId>
<version>4.12version>
<scope>testscope>
dependency>
<dependency>
<groupId>org.aspectjgroupId>
<artifactId>aspectjweaverartifactId>
<version>1.6.8version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-aopartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-contextartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-context-supportartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-ormartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-beansartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-coreartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>org.hibernategroupId>
<artifactId>hibernate-coreartifactId>
<version>${hibernate.version}version>
dependency>
<dependency>
<groupId>org.hibernategroupId>
<artifactId>hibernate-entitymanagerartifactId>
<version>${hibernate.version}version>
dependency>
<dependency>
<groupId>org.hibernategroupId>
<artifactId>hibernate-validatorartifactId>
<version>5.2.1.Finalversion>
dependency>
<dependency>
<groupId>c3p0groupId>
<artifactId>c3p0artifactId>
<version>${c3p0.version}version>
dependency>
<dependency>
<groupId>log4jgroupId>
<artifactId>log4jartifactId>
<version>${log4j.version}version>
dependency>
<dependency>
<groupId>org.slf4jgroupId>
<artifactId>slf4j-apiartifactId>
<version>${slf4j.version}version>
dependency>
<dependency>
<groupId>org.slf4jgroupId>
<artifactId>slf4j-log4j12artifactId>
<version>${slf4j.version}version>
dependency>
<dependency>
<groupId>mysqlgroupId>
<artifactId>mysql-connector-javaartifactId>
<version>${mysql.version}version>
dependency>
<dependency>
<groupId>org.springframework.datagroupId>
<artifactId>spring-data-jpaartifactId>
<version>1.9.0.RELEASEversion>
dependency>
<dependency>
<groupId>org.springframeworkgroupId>
<artifactId>spring-testartifactId>
<version>${spring.version}version>
dependency>
<dependency>
<groupId>javax.elgroupId>
<artifactId>javax.el-apiartifactId>
<version>2.2.4version>
dependency>
<dependency>
<groupId>org.glassfish.webgroupId>
<artifactId>javax.elartifactId>
<version>2.2.4version>
dependency>
dependencies>
2.3 整合Spring Data JPA与Spring
xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xmlns:task="http://www.springframework.org/schema/task"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd
http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/data/jpa
http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="com.mysql.jdbc.Driver"/>
<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/test"/>
<property name="user" value="root"/>
<property name="password" value="12345"/>
bean>
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="packagesToScan" value="com.hdh.entity"/>
<property name="persistenceProvider">
<bean class="org.hibernate.jpa.HibernatePersistenceProvider"/>
property>
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<property name="generateDdl" value="false"/>
<property name="database" value="MYSQL"/>
<property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect"/>
<property name="showSql" value="true"/>
bean>
property>
<property name="jpaDialect">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"/>
property>
bean>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory"/>
bean>
<jpa:repositories base-package="com.hdh.dao"
transaction-manager-ref="transactionManager"
entity-manager-factory-ref="entityManagerFactory">jpa:repositories>
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<tx:method name="save*" propagation="REQUIRED"/>
<tx:method name="insert*" propagation="REQUIRED"/>
<tx:method name="update*" propagation="REQUIRED"/>
<tx:method name="delete*" propagation="REQUIRED"/>
<tx:method name="get*" read-only="true"/>
<tx:method name="find*" read-only="true"/>
<tx:method name="*" propagation="REQUIRED"/>
tx:attributes>
tx:advice>
<aop:config>
<aop:pointcut id="pointcut" expression="execution(* com.hdh.service.*.*(..))"/>
<aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut"/>
aop:config>
<context:component-scan base-package="com.hdh">context:component-scan>
beans>
2.4使用JPA注解配置映射关系
@Entity //声明实体类
@Table(name = "cst_customer") //建立实体类和表的映射关系
public class Customer {
@Id//声明当前私有属性为主键
@GeneratedValue(strategy = GenerationType.IDENTITY) //配置主键的生成策略
@Column(name = "cust_id") //指定和表中cust_id字段的映射关系
private Long custId;
@Column(name = "cust_name") //指定和表中cust_name字段的映射关系
private String custName;
@Column(name = "cust_source")//指定和表中cust_source字段的映射关系
private String custSource;
@Column(name = "cust_industry")//指定和表中cust_industry字段的映射关系
private String custIndustry;
@Column(name = "cust_level")//指定和表中cust_level字段的映射关系
private String custLevel;
@Column(name = "cust_address")//指定和表中cust_address字段的映射关系
private String custAddress;
@Column(name = "cust_phone")//指定和表中cust_phone字段的映射关系
private String custPhone;
//get set省略
}
3.1 使用Spring Data JPA完成需求
3.2编写符合Spring Data JPA规范的Dao层接口
Spring Data JPA是spring提供的一款对于数据访问层（Dao层）的框架，使用Spring Data JPA，只需要按照框架的规范提供dao接口，不需要实现类就可以完成数据库的增删改查、分页查询等方法的定义，极大的简化了我们的开发过程。
在Spring Data JPA中，对于定义符合规范的Dao层接口，我们只需要遵循以下几点就可以了：
1.创建一个Dao层接口，并实现JpaRepository和JpaSpecificationExecutor
2.提供相应的泛型
/**
* 符合SpringDataJpa的dao层接口规范
* JpaRepository<操作的实体类类型，实体类中主键属性的类型>
* * 封装了基本CRUD操作
* JpaSpecificationExecutor<操作的实体类类型>
* * 封装了复杂查询（分页）
*/
public interface CustomerDao extends JpaRepository, JpaSpecificationExecutor {
}
3.3完成基本CRUD操作
完成了Spring Data JPA的环境搭建，并且编写了符合Spring Data JPA 规范的Dao层接口之后，就可以使用定义好的Dao层接口进行客户的基本CRUD操作
//申明spring提供的单元测试环境
@RunWith(SpringJUnit4ClassRunner.class)
//指定加载spring容器
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class CustomerDaoTest {
@Autowired
private CustomerDao customerDao;
/**
* 根据id查询
*/
@Test
public void testFindOne() {
Customer customer = customerDao.findOne(1L);
System.out.println(customer);
}
/**
* 保存或者更新
* 根据你传入的对象是否存在主键 存在：则是更新
* 不存：在则是保存
*jap在保存或者更新 会先发送一条查询语句
*/
@Test
public void testSave() {
Customer customer = new Customer();
customer.setCustId(2l);
customer.setCustName("xj");
Customer save = customerDao.save(customer);
System.out.println(save);
}
@Test
public void testUpdate() {
Customer customer = new Customer();
customer.setCustId(2l);
customer.setCustName("xj11");
Customer save = customerDao.save(customer);
System.out.println(save);
}
/**
* ge根据id删除
*/
@Test
public void testDelete() {
customerDao.delete(2l);
}
/**
* ge根据id删除
*/
@Test
public void testSelectAll() {
List customers= customerDao.findAll();
customers.forEach(System.out::println);
}
}