Spring ORM (Hibernate + MySql)

ORM

- ORM(Object-relational mapping) 데이터베이스와 객체 지향 프로그래밍 언어간의 호환되지 않는
  데이터를 맵핑하는 프로그래밍기법이다. 객체 모델과 관게형모델간의 불일치를 해결해 준다.

사용 이점

1. 객체 지향적으로 데이터를 관리하기 때문에 직관적이다.
2. catch/throws 및 예외 선언없이 적절한 계층에서 처리가 가능하다.
3. JDBC 관련 코드는 O/R 매핑을 수행하는 데 사용하는 코드와 트랜잭션 방식으로 통합 할 수 있다.
4. 지속성 관련 코드의 각 부분을 제외하고 테스트하는 것이 쉽다.

Demo Application

기술 스택

- Spring 5.2.8.RELEASE
- Spring Tool Suite(STS)
- JDK 1.8
- Hibernate 5.5.2.Final
- c3p0 0.9.5.5
- MySQL Connector 8.0.25
- MySQL 8.0.25
- Maven 3.8.0

pom.xml

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

<dependency>
	<groupId>mysql</groupId>
	<artifactId>mysql-connector-java</artifactId>
	<version>8.0.25</version>
</dependency>

<dependency>
	<groupId>com.mchange</groupId>
	<artifactId>c3p0</artifactId>
	<version>0.9.5.5</version>
</dependency>

​

IoC 접근 hibernate 인스턴스 등록

<?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:context="http://www.springframework.org/schema/context"
	xmlns:tx="http://www.springframework.org/schema/tx"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans	http://www.springframework.org/schema/beans/spring-beans-4.3.xsd		
		http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.3.xsd
		http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.3.xsd">

	<context:annotation-config />

	<context:property-placeholder location="classpath:properties/database.properties" />

	<context:component-scan base-package="ideatec.edu.spring.frwk.tomcat" />
	<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource"
		destroy-method="close">
		<property name="driverClass" 	value="${jdbc.driverClass}" />
		<property name="jdbcUrl" 		value="${jdbc.jdbcUrl}" />
		<property name="user" 			value="${jdbc.user}" />
		<property name="password" 		value="${jdbc.password}" />
	</bean>

	<bean id="sessionFactory"
		class="org.springframework.orm.hibernate5.LocalSessionFactoryBean">
		<property name="dataSource" ref="dataSource" />
		<property name="packagesToScan" value="ideatec.edu.spring.frwk.tomcat.entity" />
		<property name="hibernateProperties">
			<props>
				<prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
				<prop key="hibernate.show_sql">true</prop>
				<prop key="hbm2ddl.auto">create</prop>
			</props>
		</property>
	</bean>

	<bean id="transactionManager"
		class="org.springframework.orm.hibernate5.HibernateTransactionManager">
		<property name="sessionFactory" ref="sessionFactory" />
	</bean>
	<tx:annotation-driven transaction-manager="transactionManager" />
</beans>

​

properties 등록

jdbc.jdbcUrl=jdbc:mysql://localhost:3306/ideatec?characterEncoding=utf8&serverTimezone=Asia/Seoul
jdbc.driverClass=com.mysql.cj.jdbc.Driver
jdbc.user=root ##mysql user id
jdbc.password=0000 ##mysql user password

​

프로젝트구조

Entity

@Entity
@NoArgsConstructor
@Getter
@Setter
@ToString
@Table(name = "customer")
public class Customer {
	
	@Id
	@GeneratedValue(strategy = GenerationType.IDENTITY)
	@Column(name = "id")
	private int id;

	@Column(name = "first_name")
	private String firstName;

	@Column(name = "last_name")
	private String lastName;

	@Column(name = "email")
	private String email;
	
}

DAO

@Repository
public class CustomerDAOImpl implements CustomerDAO {

	@Autowired
	private SessionFactory sessionFactory;

	@SuppressWarnings("unchecked")
	@Override
	public List<Customer> getCustomers() {
		Session session = sessionFactory.getCurrentSession();
		CriteriaBuilder cb = session.getCriteriaBuilder();
		CriteriaQuery < Customer > cq = cb.createQuery(Customer.class);
		Root < Customer > root = cq.from(Customer.class);
		cq.select(root);
		Query query = session.createQuery(cq);
		return query.getResultList();
	}
	
	@Override
	public void saveOrUpdateCustomer(Customer theCustomer) {
		Session currentSession = sessionFactory.getCurrentSession();
		currentSession.saveOrUpdate(theCustomer);
	}

	@Override
	public void deleteCustomer(int id) {
		Session session = sessionFactory.getCurrentSession();
		Customer customer = session.byId(Customer.class).load(id);
		session.delete(customer);
	}
}

Controller

@RestController
@RequestMapping("/api")
public class CustomerController {

	@Autowired
	private CustomerService customerService;

	@GetMapping("/v1/customer/list")
	public ResponseEntity<?> listCustomers() throws Exception {
		List < Customer > customers = customerService.getCustomers();
		ObjectMapper objectMapper = new ObjectMapper();
		String jsonArrayString = objectMapper.writeValueAsString(customers);
		return new ResponseEntity<String>(jsonArrayString, HttpStatus.OK);
	}

	@PostMapping("/v1/customer/save")
	public String saveCustomer(@RequestBody Customer customer) {
		customerService.saveOrUpdateCustomer(customer);
		return "save";
	}
	
	@DeleteMapping("/v1/customer/delete/{id}")
	public String deleteCustomer(@PathVariable int id) {
		customerService.deleteCustomer(id);
		return "delete";
	}
}

#### Result

Log