SpringData _day01_jpa的入门

1.orm思想和以及jpa的概述和jpa的基本操作

　简单的说：ORM就是建立实体类和数据库表之间的关系，从而达到操作实体类就相当于操作数据库表的目的。

orm思想
    主要目的：操作实体类就相当于操作数据库表
    建立两个映射关系：
        实体类和表的映射关系
        实体类中属性和表中字段的映射关系
    不再重点关注：sql语句
    实现了ORM思想的框架：mybatis，hibernate

2.hibernate框架介绍

　　Hibernate是一个开放源代码的对象关系映射框架，
        它对JDBC进行了非常轻量级的对象封装，
        它将POJO与数据库表建立映射关系，是一个全自动的orm框架

3. JPA

jpa规范，实现jpa规范，内部是由接口和抽象类组成

JPA规范本质上就是一种ORM规范，注意不是ORM框架——因为JPA并未提供ORM实现，它只是制订了一些规范，提供了一些编程的API接口，但具体实现则由服务厂商来提供实现。

3.1JPA与hibernate的关系

JPA和Hibernate的关系就像JDBC和JDBC驱动的关系，JPA是规范，Hibernate除了作为ORM框架之外，它也是一种JPA实现。JPA怎么取代Hibernate呢？JDBC规范可以驱动底层数据库吗？答案是否定的，也就是说，如果使用JPA规范进行数据库操作，底层需要hibernate作为其实现类完成数据持久化工作。

4.Spring Data JPA的快速入门

　　1>创建maven工程导入依赖的jar坐标

<properties>
        <spring.version>4.2.4.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>4.9</version>
            <scope>test</scope>
        </dependency>

        <!-- spring beg -->
        <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支持的包-->
        <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>

        <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>4.2.4.RELEASE</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>配置JPA的核心配置文件

<?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">

    <!--spring和spring datajpa的配置-->

    <!--1. 创建entityManagerFactory对象交给spring容器管理-->
    <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="datasource"></property>
        <property name="packagesToScan" value="com.hdh.domain"></property>
        <!--jpa的实现厂家-->
        <property name="persistenceProvider">
            <bean class="org.hibernate.jpa.HibernatePersistenceProvider"></bean>
        </property>

        <!--jpa的供应商适配器-->
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <!--generateDdl 配置是否自动创建数据库表-->
                <property name="generateDdl" value="false"/>
                <!--database 指定数据库类型-->
                <property name="database" value="MYSQL"/>
                <!--数据库方言：支持特有的语法-->
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect"/>
                <!--是否显示sql语句-->
                <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"></bean>
        </property>
    </bean>

    <!--2.创建数据库连接池-->
    <bean id="datasource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value="root"></property>
        <property name="password" value="12345"></property>
        <property name="jdbcUrl" value="jdbc:mysql:///jpa"></property>
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
    </bean>

    <!-- 3.整合spring data jpa-->
    <jpa:repositories base-package="com.hdh.dao" transaction-manager-ref="transactionManager"
                      entity-manager-factory-ref="entityManagerFactory">
    </jpa:repositories>
    <!--4.配置事务管理器-->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>

    <!-- 5.txAdvice声明式事务-->
    <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>

3> 使用JPA注解配置映射关系(get,set,tostring省略)

/**
 * 客户的实体类
 *     配置映射关系：
 *         1.实体类和表的映射关系
 *         @Entity 声明是实体类
 *         @Table(name = "cst_customer") 表示对应数据库中的表
 *
 *         2.实体类中属性和表中字段的映射
 */

@Entity
@Table(name = "cst_customer")
public class Customer implements Serializable {
    /**@Id  主键
     * @GeneratedValue 配置主键的生成策略
     *                    GenerationType.IDENTITY 自增  条件：数据库必须支持自动增长
     *                    GenerationType.SEQUENCE 序列  条件：数据库必须支持序列，Oracle支持
     *                    GenerationType.TABLE     jpa提供的一种机制，通过一张数据库表的形式帮助我们完成主键自增
     *                    GenerationType.AUTO      由程序自动帮我们选择
     * @Column          实体类中属性和表中字段的映射
     */
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "cust_id")
    private Long custId;//客户主键
    @Column(name = "cust_name")
    private String custName;//客户姓名
    @Column(name = "cust_source")
    private String custSource;//客户来源
    @Column(name = "cust_industry")
    private String custIndustry;//客户所属行业
    @Column(name = "cust_level")
    private String custLevel;//客户等级
    @Column(name = "cust_address")
    private String custAddress;//客户地址
    @Column(name = "cust_phone")
    private String custPhone;//客户电话

4> 编写符合Spring Data JPA规范的Dao层接口

/**
 * 符合SpringDataJpa的dao层接口规范
 * 1.JpaRepository<操作的实体类类型，主键的类型>  封装了CRUD
 * <p>
 * 2.paSpecificationExecutor<操作的实体类类型>   封装了复杂查询
 */
public interface CustomerDao extends JpaRepository<Customer, Long>, JpaSpecificationExecutor<Customer> {
}

5>测试 完成基本CRUD操作

@RunWith(SpringJUnit4ClassRunner.class)//声明spring提供的单元测试
@ContextConfiguration(locations = "classpath:application.xml") //指定spring的配置文件
public class CustomerDaoTest {
    @Autowired
    private CustomerDao customerDao;

    /**
     * 更具id查询
     */
    @Test
    public void findOne() {
        Customer customer = customerDao.findOne(2l);
        System.out.println(customer);
    }

    /**
     * save:保存或者更新
     * 根据传递的对象是否存在直接id，如果没有主键则为保存
     * 如果有主键则为更新
     */
    @Test
    public void save() {
        Customer customer = new Customer();
        customer.setCustId(8l);
        customer.setCustName("hdh");
        customer.setCustLevel("vip");
        customer.setCustSource("学生");
        customerDao.save(customer);
    }

    @Test
    public void update() {
        Customer customer = new Customer();
        customer.setCustId(8l);
        customer.setCustName("哈哈哈");
        customerDao.save(customer);
    }

    @Test
    public void delete() {
        customerDao.delete(8l);
    }

    /**
     * 查询所有
     */
    @Test
    public void findAll() {
        List<Customer> list = customerDao.findAll();
        for (Customer customer : list) {
            System.out.println(customer);

        }
    }

    /**
     * 统计查询所有 count
     */
    @Test
    public void count() {
        long count = customerDao.count();
        System.out.println(count);
    }

    /**
     * 判断id=4l的客户是否存在
     */
    @Test
    public void exists() {
        boolean exists = customerDao.exists(4l);
        System.out.println(exists);
    }

    /**
     * 根据id从数据库查询
     *    需要加Transactional
     *  findOne：立即加载
     *  getOne：延迟加载
     */
    @Test
    @Transactional
    public void getOne() {
        Customer customer = customerDao.getOne(4l);
       // System.out.println(customer);
    }

}