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.RELEASE</spring.version>
        <hibernate.version>5.0.7.Final</hibernate.version>
        <slf4j.version>1.6.6</slf4j.version>
        <log4j.version>1.2.12</log4j.version>
        <c3p0.version>0.9.1.2</c3p0.version>
        <mysql.version>5.1.6</mysql.version>
    </properties>

    <dependencies>
        <!-- junit单元测试 -->
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <!-- spring beg  AOP-->
        <dependency>
            <groupId>org.aspectj</groupId>
            <artifactId>aspectjweaver</artifactId>
            <version>1.6.8</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-aop</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context-support</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- spring对orm框架的支持包-->
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-orm</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-beans</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-core</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- spring end -->

        <!-- hibernate beg -->
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-core</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-entitymanager</artifactId>
            <version>${hibernate.version}</version>
        </dependency>
        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>5.2.1.Final</version>
        </dependency>
        <!-- hibernate end -->

        <!-- c3p0 beg -->
        <dependency>
            <groupId>c3p0</groupId>
            <artifactId>c3p0</artifactId>
            <version>${c3p0.version}</version>
        </dependency>
        <!-- c3p0 end -->

        <!-- log end -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>${log4j.version}</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-api</artifactId>
            <version>${slf4j.version}</version>
        </dependency>

        <dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-log4j12</artifactId>
            <version>${slf4j.version}</version>
        </dependency>
        <!-- log end -->


        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>${mysql.version}</version>
        </dependency>

        <!-- spring data jpa 的坐标-->
        <dependency>
            <groupId>org.springframework.data</groupId>
            <artifactId>spring-data-jpa</artifactId>
            <version>1.9.0.RELEASE</version>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
        </dependency>

        <!-- el beg 使用spring data jpa 必须引入 -->
        <dependency>
            <groupId>javax.el</groupId>
            <artifactId>javax.el-api</artifactId>
            <version>2.2.4</version>
        </dependency>

        <dependency>
            <groupId>org.glassfish.web</groupId>
            <artifactId>javax.el</artifactId>
            <version>2.2.4</version>
        </dependency>
        <!-- el end -->
    </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">

    <!-- 1.dataSource 配置数据库连接池-->
    <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>

    <!-- 2.配置entityManagerFactory 对象交给spring容器来管理-->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <!--配置要扫描的包（实体类所在的包）-->
        <property name="packagesToScan" value="com.hdh.entity"/>
        <!--jpa的实现厂家-->
        <property name="persistenceProvider">
            <bean class="org.hibernate.jpa.HibernatePersistenceProvider"/>
        </property>
        <!--JPA的供应商适配器-->
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <!--是否自动创建表-->
                <property name="generateDdl" value="false"/>
                <!--指定数据库的类型-->
                <property name="database" value="MYSQL"/>
                <!--数据库方言  支持的数据库语法-->
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect"/>
                <!--控制台是否显示打印sql-->
                <property name="showSql" value="true"/>
            </bean>
        </property>
        <!--jpa的方言：高级的特性-->
        <property name="jpaDialect">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect"/>
        </property>
    </bean>


    <!-- 3.事务管理器-->
    <!-- JPA事务管理器  -->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

    <!-- 整合spring data jpa-->
    <jpa:repositories base-package="com.hdh.dao"
                      transaction-manager-ref="transactionManager"
                      entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>

    <!-- 4.txAdvice-->
    <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>

    <!-- 5.aop-->
    <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>

    <!--组装其它 配置文件-->

</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<Customer, Long>, JpaSpecificationExecutor<Customer> {

}

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<Customer> customers= customerDao.findAll();
        customers.forEach(System.out::println);

    }


}