JPA Configuration

• 등록해야 할 Bean List
• DataSource
• JpaVendorAdapter : 어떤 jpa 구현체를 사용할 것인지를 명시해줌

SPI interface that allows to plug in vendor-specific behavior into Spring’s EntityManagerFactory creators.

• LocalContainerEntityManagerFactoryBean : entity를 관리하는 entityManager를 만들어 줌
• PlatformTransactionManager : transaction을 관리하는 bean

• 그러나 아래의 과정은 application.yaml에 잘 써주면 알아서 Autoconfiguration해줌

@Configuration
public class DataSourceConfig {

    @Bean
    public DataSource dataSource(){
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("org.h2.Driver");
        dataSource.setUrl("jdbc:h2:~/test");
        dataSource.setUsername("sa");
        dataSource.setPassword("");
        return dataSource;
    }

    @Bean // 어떤 jpa 구현체를 사용할 것인지를 명시해주는 bean
    public JpaVendorAdapter jpaVendorAdapter(JpaProperties jpaProperties){
        AbstractJpaVendorAdapter jpaVendorAdapter = new HibernateJpaVendorAdapter();
        jpaVendorAdapter.setShowSql(jpaProperties.isShowSql());
        jpaVendorAdapter.setDatabasePlatform(jpaProperties.getDatabasePlatform());
        jpaVendorAdapter.setGenerateDdl(jpaProperties.isGenerateDdl());

        return jpaVendorAdapter;
    }

    @Bean // Jpa에서 entity는 rdb의 table과 매핑되는 객체인데 entity를 관리하는 entityManager가 있고 얘를 만들어주는 애(entityManagerFactory)
    public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource,
                                                                           JpaVendorAdapter jpaVendorAdapter,
                                                                           JpaProperties jpaProperties){
        LocalContainerEntityManagerFactoryBean em = new LocalContainerEntityManagerFactoryBean();
        em.setDataSource(dataSource);
        em.setPackagesToScan("com.example.springjpa.domain");
        em.setJpaVendorAdapter(jpaVendorAdapter);

        Properties properties = new Properties();
        properties.putAll(jpaProperties.getProperties());
        em.setJpaProperties(properties);
        return em;
    }

    @Bean // transaction을 관리하는 Bean
    public PlatformTransactionManager transactionManager(LocalContainerEntityManagerFactoryBean entityManagerFactoryBean){
        JpaTransactionManager transactionManager = new JpaTransactionManager();
        transactionManager.setEntityManagerFactory(entityManagerFactoryBean.getObject());

        return transactionManager;
    }
}

spring:
  h2:
    console:
      enabled: true

  jpa:
    generate-ddl: true
#    hibernate:
#      ddl-auto: create-drop. 이런 식으로 작성하면 autoconfiguration일 때 동작함
    open-in-view: false
    show-sql: true

    database: h2
    properties:
      hibernate:
        dialect: org.hibernate.dialect.H2Dialect
        query.in_clause_parameter_padding: true
        hbm2ddl:
          auto: create-drop

• 지금은 위에서 jpaProperties.getProperties() 로 셋팅해주고 있기 때문에 ddl-auto를 위와같이 명시해야함

Read replica 와 Write replica로 분산처리하기