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August 11, 2021 16:21
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JPA 2강 : JpaMain.java
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package jpabook.start; | |
import javax.persistence.*; | |
import java.util.List; | |
public class JpaMain { | |
public static void main(String[] args) { | |
//엔티티 매니저 팩토리 생성 | |
EntityManagerFactory emf = Persistence.createEntityManagerFactory("jpabook"); | |
EntityManager em = emf.createEntityManager(); //엔티티 매니저 생성 | |
EntityTransaction tx = em.getTransaction(); //트랜잭션 기능 획득 | |
try { | |
tx.begin(); //트랜잭션 시작 | |
logic(em); //비즈니스 로직 | |
tx.commit();//트랜잭션 커밋 | |
} catch (Exception e) { | |
e.printStackTrace(); | |
tx.rollback(); //트랜잭션 롤백 | |
} finally { | |
em.close(); //엔티티 매니저 종료 | |
} | |
emf.close(); //엔티티 매니저 팩토리 종료 | |
} | |
public static void logic(EntityManager em) { | |
String id = "id1"; | |
Member member = new Member(); | |
member.setId(id); | |
member.setUsername("지한"); | |
member.setAge(2); | |
//등록 | |
em.persist(member); | |
//수정 | |
member.setAge(20); | |
//한 건 조회 | |
Member findMember = em.find(Member.class, id); | |
System.out.println("findMember=" + findMember.getUsername() + ", age=" + findMember.getAge()); | |
//목록 조회 | |
List<Member> members = em.createQuery("select m from Member m", Member.class).getResultList(); | |
System.out.println("members.size=" + members.size()); | |
//삭제 | |
em.remove(member); | |
} | |
} |
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