Spring Data JPA的入门

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 -->
    <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>

整合Spring Data JPA与Spring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 data jpa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" />
        <!--配置的扫描的包（实体类所在的包） -->
        <property name="packagesToScan" value="com.leewle.domain" />
        <!-- 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">
                <!--配置是否自动创建数据库表 -->
                <property name="generateDdl" value="false" />
                <!--指定数据库类型 -->
                <property name="database" value="MYSQL" />
                <!--数据库方言：支持的特有语法 -->
                <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
                <!--是否显示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>
    <!--2.创建数据库连接池-->
    <bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value="root"/>
        <property name="password" value="123"/>
        <property name="driverClass" value="com.mysql.jdbc.Driver"/>
        <property name="jdbcUrl" value="jdbc:mysql:///jpa?useUnicode=true&amp;characterEncoding=utf8"/>
    </bean>
    <!--3.整合spring data jpa-->
    <jpa:repositories base-package="com.leewle.dao" transaction-manager-ref="transactionManager" entity-manager-factory-ref="entityManagerFactory"/>
    <!--4.配置事务管理器-->
    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerFactory"/>
    </bean>
    <!--声明式事务-->
    <!--6.配置包扫描-->
    <context:component-scan base-package="com.leewle"></context:component-scan>
</beans>

使用JPA注解配置映射关系

@Entity
@Table(name = "cst_customer")
public class Customer {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "cust_id")
    private Long custId;  //客户的主键

    @Column(name = "cust_name")
    private String custName; //客户名称

    @Column(name = "cust_source")
    private String custSource; //客户来源

    @Column(name = "cust_level")
    private String custLevel; //客户级别

    @Column(name = "cust_industry")
    private String custIndustry; //客户所属行业

    @Column(name = "cust_phone")
    private String custPhone; //客户的联系方式

    @Column(name = "cust_address")
    private String custAddress; //客户地址
}

符合Spring Data JPA规范的Dao层接口

要求：

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Spring Data Jpa的dao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(分页查询)
public interface CustomerDao extends JpaRepository<Customer, Long>, JpaSpecificationExecutor<Customer> {
}

基本CRUD操作的实现

//声明spring提供的单元测试环境
//指定spring容器的配置信息
@RunWith(SpringJUnit4ClassRunner.class) 
@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
     //   根据传递的对象是否存在主键id,如果没有id主键属性：保存
     //   存在id主键属性，根据id查询数据，更新数据
    @Test
    public void testSave(){
        Customer customer = new Customer();
        customer.setCustName("LEE");
        customer.setCustLevel("vip");
        customer.setCustIndustry("工地");
        customerDao.save(customer);
    }
    @Test
    public void testUpdate(){
        Customer customer = new Customer();
        customer.setCustId(4l);
        customer.setCustName("WLE");
        customer.setCustLevel("vip");
        customer.setCustIndustry("车间");
        customerDao.save(customer);
    }

	//删除操作（根据id）
    @Test
    public void testDelete(){
        customerDao.delete(4l);
    }

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

    //查询客户的总数量
    @Test
    public void testCount(){
        long count = customerDao.count();
        System.out.println(count);
    }

    //根据id 查询客户是否存在
    @Test
    public void testExists(){
        boolean exists = customerDao.exists(1L);
        System.out.println(exists);
    }

    //根据id从数据库查询
	//	 findOne:立即加载
	//	 getOne：延迟加载
    @Test
    @Transactional //保证getOne正常运行
    public void testGetOne(){
        Customer customer = customerDao.getOne(1l);
        System.out.println(customer);
    }
}