What is persistence in java

Definition and examples about Persistence in Java
Example Structures to develop with persistence programming java

1. What is Persistence in Java 김 병 부 (Benjamin Kim) [email protected] http://myboor.tistory.com

2. About what? History JPA Features Persistence ORM JPA CRUD JPA Entity LifeCycle Why Hibernate ? Spring Data JPA

3. Market Situation

4. Market Situation

5. Hibernate VS MyBatis VS JDBC Criteria JDBC MyBatis Hibernate Learning Curve Simple to learn Simple to learn Many aspects to learn Work in data centric env Good, mapping efforts exits Naturally fits Mapping issues, low performance Work in obj centric env Major mapping efforts Good, limited feature amount Naturally fits Object Mapping Manual, hard to support Maps methods to statements Transparent persistence Query Language Native SQL Native SQL HQL, Native SQL, Criteria API Caching Poor, manual or 3 rd party Good customization 3 level , advanced customization

6. Hibernate VS MyBatis VS JDBC Performance test Test JDBC MyBatis Hibernate Read 5k Employees 0.51 0.77 8.09 Create and Insert 10 Employees 0.73 0.9 0.67 Update 10 Employees 0.58 0.55 0.7 Update 10 Employee Addresses 0.28 0.2 0.41 Cascade delete of 10 Employees 2.25 0.71 0.79

7. History EJB-Entity Bean Hibernate JPA v1.0 (2006. 5) JPA v2.0 (2009.12) JPA v2.1 (2013) Spring Data Spring-Data-JPA

8. History JPA OpenJPA EclipseLink Hibernate

9. JPA Features JPA 2.0 Expanded object-relational mapping functionality Criteria query API Query Hints 표준 DDL 생성 metadata 표준 Validation Shared Object cache support JPA 2.1 Converters - allowing custom code conversions between database and object types. Criteria Update/Delete - allows bulk updates and deletes through the Criteria API. Stored Procedures Schema Generation Entity Graphs - allow partial or specified fetching or merging of objects. JPQL/Criteria 강화 - arithmetic sub-queries, generic database functions, join ON clause, TREAT option.

10. Persistence Persistence 사전적 의미 : 고집 , 지속 , 영속성 or 영속화 보편적 의미의 Persistence 는 Application 이나 Object 가 수명을 다했을 때도 , Object 의 데이터가 저장되는 것을 의미한다 . 저장소 : DBMS, File 등등 Persistence Object in JAVA 이미 익숙한 객체 POJO 기반의 클래스 객체 Java Bean Style – private 속성 , getter/setter Persistence Object = Table 의 1 개 Row

11. ORM ORM (Object-Relational Mapping) 관계형 데이터와 객체 데이터를 서로 맵핑 시키는것 . Persistence Object 를 처리 해주는 것 . E.g. Hibernate F/W What is difference between Mybatis and Hibernate Database-centric VS Object-centric Mybatis is focusing on SQL Mapping Persistent F/W Hibernate is focusing on ORM framework

12. JPA CRUD EntityManager Application-managed EntityManager , Container-managed EntityManager DB 에서 Entity 와 관련된 작업 API(CRUD) 를 제공한다 . Create Read, Update, Delete @ PersistenceContext private EntityManagerFactory emf ; // ... EntityManager em = emf.createEntityManager (); Customer customer = new Customer(id, name, address); em.persist (customer); Customer customer = em.find ( Customer.class , id); // Read customer.setAddress (“new Address String”); // Update em.remove (customer) // Delete

13. JPA Entity LifeCycle NEW Entity 인스턴스만 생성된 상태 – DB 와 연결이 없다 . Managed Persistence Context 에 의해서 관리되는 상태 Entity 내부 속성값이 바뀌면 DB 에 반영 (Update 됨 ) Detached Entity Instance 가 Persistence Context 에 의해서 관리되지 않는 상태 EntityManager 의 merge() 로 Managed 상태로 천이 가능 Removed DB 에서 Entity 가 삭제되는 상태

14. Why Hibernate? Advantage DDD 생산성 이식성 트렌드 Disadvantage 성능에 대한 부담감 복잡한 Domain 구조에서의 부족한 설계 경험 너무나 익숙한 SQL 그럼에도 불구하고 Hibernate.

15. Why Hibernate? Hibernate supported Databases MySQL ( innoDB , MyISAM ) Oracle (any version) DB2 PostgreSQL Informix H2 DERBY SQL_SERVER SYBASE

16. Spring Data JPA http ://projects.spring.io/spring-data / One of sub project of Spring-DATA MongoDB , NEO4J, REDIS, SOLAR, HADOOP, ElasticSearch , CouchBase , Cassandra, DynamoDB , JDBC Extentions Anti - Boiler-plate structure 정해진 규칙에 따라 인터페이스 생성시 단순 노동을 줄일 수 있음

17. Spring Data JPA In case of Mybatis , to develop User domain UserMapper.xml CRUD Queries and Another Search Queries UserMapper.java interface CRUD Methods and Another Search Methods mapped with UserMapper.xml UserDao.java interface CRUD and Search Methods for DAO Layer UserDaoImpl.java class CRUD and Search implementation Methods UserValue domain class In case of Hibernate, to develop User domain Only required UserRepository similar to UserDao interface. That’s all User domain class with some annotation

18. Spring Data JPA Entity

19. Spring Data JPA Repository org.springframework.data.Repository Interface in Spring-Data-JPA

20. Spring Data JPA Repository Naming Rule Operation Rule Read T findOne (ID primaryKey ) List<T> findAll () List<T> findByDeptName (String deptName ) List<T> findByDeptNameAndPhone (String deptName , phone) List<T> findByPhoneIn (Collection<String> phones) List<T> findByNameStartingWith (String name) List<T> findByNameEndingWith (String name) List<T> findByNameIgnoreCase (String name) Long count() Long countByDeptName (String deptName ) Create T save(T t) Delete void delete(Long id); void delete(T t); void delete(List<T> entities); void deleteAll ();

21. Spring Data JPA 검색조건 Specification org.springframework.data.jpa.domain.Specification 정렬조건 org.springframework.data.domain. Sort 페이징 처리 org.springframework.data.domain.Pageable

22. Spring Data JPA <<interface>> Repository <<interface>> CrudRepository <<interface>> PagingAndSortingRepository <<interface>> JpaRepository <<interface>> JpaSpecificationExecutor

23. Development Stack

24. Reference Link http:// en.wikipedia.org/wiki/Java_Persistence_API http :// www.javajigi.net/pages/viewpage.action?pageId=5924 http:// www.youtube.com/watch?v=OOO4H3BAetU http ://hibernate.org/orm/what-is-an-orm / http://www.slideshare.net/iwish1hadanose/hibernate-vs-my-batis-vs-jdbc-is-there-a-silver-bullet http://zeroturnaround.com/rebellabs/