[Java] JPA

...
</build>
	<dependencies>
		<dependency>
			<groupId>javax.persistence</groupId>
			<artifactId>javax.persistence-api</artifactId>
			<version>2.2</version>
		</dependency>
		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-entitymanager</artifactId>
			<version>5.4.2.Final</version>
		</dependency>

		<!-- lombok 사용 -->
		<dependency>
			<groupId>org.projectlombok</groupId>
			<artifactId>lombok</artifactId>
			<version>1.18.20</version>
		</dependency>
		
		<!-- oracle driver의 설정 -->
		<dependency>
			<groupId>com.jslsolucoes</groupId>
			<artifactId>ojdbc6</artifactId>
			<version>11.2.0.1.0</version>
		</dependency>
	</dependencies>
		
	<!-- oracle driver의 추가 설정 정보 -->
	<repositories>
		<repository>
			<id>oracle</id>
			<name>ORACLE JDBC Repository</name>
			<url>https://maven.atlassian.com/3rdparty/</url>
		</repository>
	</repositories>
</project>
    	

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.1" 
             xmlns="http://xmlns.jcp.org/xml/ns/persistence" 
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
             xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/persistence http://xmlns.jcp.org/xml/ns/persistence/persistence_2_1.xsd">
	
    <persistence-unit name="oracleDB">	
        <class>model.entity.Team</class>
        <class>model.entity.Member</class>

        <properties>
            <property name="javax.persistence.jdbc.driver" 
                      value="oracle.jdbc.OracleDriver" />
            <property name="javax.persistence.jdbc.url" 
                      value="jdbc:oracle:thin:@127.0.0.1:1521:xe" />
            <property name="javax.persistence.jdbc.user" 
                      value="SCOTT" />
            <property name="javax.persistence.jdbc.password" 
                      value="TIGER" />        
            
            <property name="hibernate.dialect" 
                      value="org.hibernate.dialect.OracleDialect" />	
            <property name="hibernate.show_sql" value="true" />
            <property name="hibernate.id.new_generator_mappings" value="true" />
            <property name="hibernate.hbm2ddl.auto" value="create" />
           
        </properties>
	</persistence-unit>	
</persistence>

// JDBC에서의 설계
class Member{
    private long memberId;
    private String name;
    private long teamId;
}

// JPA에서의 설계
class Member{
    private long memberId;
    private String name;
    private Team team;  // 엔티티 객체를 참조
}

@AllArgsConstructor
@NoArgsConstructor
@Setter
@Getter
@Entity
class Team{	
	@Id	
	@Column(name="team_id")
	private Long teamId;

	@Column(length=20, name="team_name")
	private String teamName;
	
    /* 해당 엔티티(Team)가 상대 엔티티(Member)의 여러 객체를 가질 수 있음 
     * `일`인 쪽에 @OneToMany를 추가하여 양방향 관계 만듬 
     * 	- 팀에서 여러 멤버들을 참조 가능하게 ArrayList 만들어준다
     * mappedBy 사용하여 연관관계의 주인을 설정해줌 
     * 	- mappedBy의 값은 대상이 되는 변수명(Member 테이블의 teamId 변수)
     */
	@OneToMany(mappedBy="teamId")       
	List<Member> members = new ArrayList<Member>();
	

@AllArgsConstructor
@NoArgsConstructor
@Setter
@Getter
@Entity
class Member{
    @Id
    @Column(name="member_id")
    private long memberId;
    
    @Column(length=20)
    private String name;
    
    // JoinColumn : 외래키를 매핑하는 애노테이션. 
    // 해당 엔티티(Member)의 여러 객체가 상대 엔티티(Team)에 대응 - 다대일 관계(@ManyToOne)
    @JoinColumn(name="team_id")  
    @ManyToOne
    private Team teamId;
}

public class RunningTest {
	
	void test() {
		EntityManagerFactory emf = Persistence.createEntityManagerFactory("oracleDB");
		EntityManager em = emf.createEntityManager();
		EntityTransaction tx = em.getTransaction();
		
        tx.begin();
		
        try{
        	// 엔티티 클래스의 setter 메소드 - tx.commit() 시에 UPDATE문 수행 
            Team t1 = new Team();
            t1.setTeamName("우리팀");

            Member m1 = new Member();
            m1.setName("장보리");
            m1.setTeamId(t1);

            Member m2 = new Member();
            m2.setName("서리태");
            m2.setTeamId(t1);

            t1.getMembers().add(m1);
            t1.getMembers().add(m2);
            
            // INSERT
            em.persist(t1);
            em.persist(m1);		
            em.persist(m2);
           
            // SELECT one
            Member oneMember = em.find(Member.class, 1L);  // pk값(1)으로 조회
            System.out.println("조회한 멤버 : " + oneMember);
            
            // SELECT list
            List<Member> allMember = em.createQuery(
                "select m from Member m", Member.class).getResultList();
            System.out.println("멤버 수 : " + allMember.size());
			
            // DELETE
            em.remove(oneMember);  // 객체를 파라미터로 받아서 pk값을 통해 해당 데이터 삭제

            tx.commit();
            
        }catch(Exception e) {
            // 에러 발생시 CRUD 결과 저장하지 않고 rollback
            tx.rollback();
            e.printStacktrace();
        }finally {
            // 자원반환
            em.close();
            emf.close();
        }
    }
	
}