Hiio.com

JPA

1. dependencies

• h2

  <dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <version>2.1.214</version>
    <scope>test</scope>
  </dependency>

• hibernate

  <dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-entitymanager</artifactId>
    <version>5.6.15.Final</version>
  </dependency>
  

- persistence.xml
```xml
<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.2"
             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/">

    <!-- EntityManagerFactory 생성 시 unit name과 일치해야 합니다 -->
    <persistence-unit name="com.hiio">
        <properties>
            <!-- 필수 속성 -->
            <!-- DB Driver -->
            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>

            <!-- DB user info -->
            <property name="javax.persistence.jdbc.user" value="hiio"/>
            <property name="javax.persistence.jdbc.password" value="hiio"/>

            <!-- DB url -->
            <property name="javax.persistence.jdbc.url" value="jdbc:h2:file:F:/data/h2/prac"/>
            <!-- Dialect -->
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>

            <!-- 옵션 -->
            <!-- SQL show -->
            <property name="hibernate.show_sql" value="true"/>

            <!-- SQL 정렬 -->
            <property name="hibernate.format_sql" value="true"/>

            <!-- SQL에 관한 주석 처리 -->
            <property name="hibernate.use_sql_comments" value="true"/>

            <!-- application 실행 시 ddl 전략 -->
            <property name="hibernate.hbm2ddl.auto" value="update"/>
        </properties>

    </persistence-unit>
</persistence>

• lombok

  <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
  <dependency>
    <groupId>org.projectlombok</groupId>
    <artifactId>lombok</artifactId>
    <version>1.18.26</version>
    <scope>provided</scope>
  </dependency>

2. Annotation

• @Entity : 테이블 매핑한다고 알려준다
• @Table : 매핑할 테이블 정보 / 생략시 class 이름을 매핑
• @Id : 식별자 필드 / 기본키
• @Column : 컬럼 매핑

3. application jpa 순선

• EntityManagerFactory 생성
• EntityyManager 생성
• EntityTransaction 생성
• 트랜잭션 begin()
• 로직
• 트랜잭션 commit()
• 에러 : rollback()
• EntityManager close()
• EntityManagerFactory close()

3. 로직

• 등록 EntityManager save + Entity Object
• find
• setter 수정
• em.remove(Entity Object) 삭제
• createQuery + getResultList
• Entity Object .class

4. 문제는 검색쿼리

• JPQL : Entity Object 를 대상으로 한다.

• Error
• No default constructor for entity: 기본 생성자 추가해주기

이클립스

1. 메모리 늘리기

• 'Preferences - General - Show heap status'를 체크
• eclipse.ini 파일을 수정
• Xms256m -> Xms1024m