Spring Data JPA——概述、Spring Data JPA的CRUD操作
目录
- 一、Spring Data JPA 概述
- 1、Spring Data JPA 与 JPA和hibernate之间的关系
- 二、Spring Data JPA入门
- 三、Spring Data JPA 完成CRUD
一、Spring Data 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！
Spring Data JPA 让我们解脱了DAO层的操作，基本上所有CRUD都可以依赖于它来实现,在实际的工作工程中，推荐使用Spring Data JPA + ORM（如：hibernate）完成操作，这样在切换不同的ORM框架时提供了极大的方便，同时也使数据库层操作更加简单，方便解耦!
1、Spring Data JPA 与 JPA和hibernate之间的关系
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-
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） -
Spring Data JPA是Spring提供的一套
对JPA操作更加高级的封装，是在JPA规范下的专门用来进行数据持久化的解决方案。
二、Spring Data JPA入门
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Spring Data JPA完成客户的基本CRUD操作
1、环境搭建
引入Spring Data JPA的坐标
<properties>
<spring.version>4.2.4.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>4.9version>
<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>4.2.4.RELEASEversion>
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>
3、Spring整合Spring Data JPA
<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="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource"/>
<property name="packagesToScan" value="com.zy.domain"/>
<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="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="com.mysql.jdbc.Driver" />
<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/jpa?useUnicode=true&characterEncoding=UTF-8" />
<property name="user" value="root" />
<property name="password" value="1111" />
bean>
<jpa:repositories base-package="com.zy.dao" transaction-manager-ref="transactionManager"
entity-manager-factory-ref="entityManagerFactory">
jpa:repositories>
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory"/>
bean>
<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>
<context:component-scan base-package="com.zy"/>
<aop:config>
<aop:pointcut id="pointcut" expression="execution(* cn.itcast.service.*.*(..))" />
<aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
aop:config>
beans>
4、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;
@Column(name="cust_address")
private String custAddress;
@Column(name="cust_industry")
private String custIndustry;
@Column(name="cust_level")
private String custLevel;
@Column(name="cust_name")
private String custName;
@Column(name="cust_phone")
private String custPhone;
@Column(name="cust_source")
private String custSource;
// 省略 getter/setter 方法
}
三、Spring Data JPA 完成CRUD
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1、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
/**
* Description: 客户dao
*
* @author zygui
* @date 2020/5/5 13:45
*/
/**
* 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>
{
}
这样我们就定义好了一个符合Spring Data JPA规范的Dao层接口
2、完成CRUD操作
/**
* Description:
*
* @author zygui
* @date 2020/5/5 13:50
*/
@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations = "classpath:applicationContext.xml")
public class CustomerDaoTest {
@Autowired
private CustomerDao customerDao;
/**
* 根据id来查询
*/
@Test
public void testFindOne() {
Customer customer = customerDao.findOne(1L);
System.out.println(customer);
}
/**
* save : 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("栗子");
customer.setCustLevel("vip");
customer.setCustIndustry("foot");
customerDao.save(customer);
}
@Test
public void testUpdate() {
Customer customer = new Customer();
customer.setCustId(4L);
customer.setCustName("鸽子1");
customer.setCustLevel("svip");
customerDao.save(customer);
}
@Test
public void testDelete() {
customerDao.delete(3L);
}
@Test
public void testFindAll() {
List<Customer> list = customerDao.findAll();
for (Customer customer : list) {
System.out.println(customer);
}
}
// 查询客户数量
@Test
public void testCount() {
long count = customerDao.count();
System.out.println(count);
}
/**
* 测试：判断id为4的客户是否存在
* 1. 可以查询以下id为4的客户
* 如果值为空，代表不存在，如果不为空，代表存在
* 2. 判断数据库中id为4的客户的数量
* 如果数量为0，代表不存在，如果大于0，代表存在
*/
@Test
public void testExists() {
boolean exists = customerDao.exists(4L);
System.out.println("id为4的客户 是否存在："+exists);
}
/**
* 根据id从数据库查询
* @Transactional : 保证getOne正常运行
*
* findOne：
* em.find() :立即加载
* getOne：
* em.getReference :延迟加载
* * 返回的是一个客户的动态代理对象
* * 什么时候用，什么时候查询
*/
@Test
@Transactional
public void testGetOne() {
Customer customer = customerDao.getOne(4L);
System.out.println(customer);
}
}