What’s new in JPA 2.0

Alin Burlacu

Java Developer @ Endava

25.11.2011

Airplane view

Why ?

Serializable

JDBC

Platform independent

More OOP like

How ?

ORM (Object-Relational Mapping)

Entity manager

JPQL (Java Persistence Query Language)

What’s new

Expanded mapping functionality

Pessimistic locking

Expanded QL

Criteria API

Cache (L2) like a standard (minimal)

Expanded mapping functionality

@Access(Type Option)

Mix access modes in a hierarchy

Combine access modes in a single class

Expanded mapping functionality

Access Type Option - CODE

@Transient to prevent the field from being

mapped in addition to the property.

Expanded mapping functionality

Orphan Removal

Only relationships with single cardinality on

the source side :

@OneToOne

@OneToMany

Expanded mapping functionality

Orphan Removal - CODE

Be aware of object lifecycle

Expanded mapping functionality

@ElementCollection

Collections of simple data types mapped in

separate tables.

Map support has been extended so that

maps can have keys and values of basic

types, entities, or embeddables

Expanded mapping functionality

@ElementCollection – CODE

(Collection of Basic Types)

Expanded mapping functionality

@ElementCollection - CODE

(Map of Basic Types)

Expanded mapping functionality

Other

@OrderColumn

@Embeded

@Embedable

@EmbededId

@OneToMany (no join Table)

Hierarchy of embedables

Relations to embedables

Pessimistic locking - CODE

Pessimistic locking - CODE

Expanded QL Timestamp literals

SELECT t from BankTransaction t

WHERE t.txTime > {ts „2008-06-0110:00:01.0‟}

IN expression may include collection parameter

SELECT emp FROM Employee emp

WHERE emp.project.id IN [:projectIds]

Non- polymorphic queries

SELECT e FROM Employee e

WHERE CLASS(e) = FullTimeEmployee OR

e.wage = “SALARY”

Expanded QL

Ordered List indexing

SELECT t FROM CreditCard c

JOIN c.transactionHistory t

WHERE INDEX(t) BETWEEN 0 AND 9

CASE statement

UPDATE Employee e SET e.salary =

CASE e.rating WHEN 1 THEN e.salary * 1.1

WHEN 2 THEN e.salary * 1.05

ELSE e.salary * 1.01

END

Criteria API

STRING-BASED CRITERIA - CODE

{

CriteriaBuilder cb = em.getCriteriaBuilder();

CriteriaQuery c =

b.createQuery(Account.class);

Root acct = c.from(Account.class);

c.select(acct) .where(

cb.equal(acct.get(“name”), “Jim”));

return em.createQuery(c).getResultList();

}

Criteria API

STRONGLY TYPED CRITERIA - CODE

{

CriteriaBuilder cb = em.getCriteriaBuilder();

CriteriaQuery<Account> c =

cb.createQuery(Account.class);

Root<Account> acct = c.from(Account.class);

c.select(acct).where(

cb.equal(acct.get(Account_.name),

“Jim”));

Return em.createQuery(c).getResultList();

}

Cache (L2) like a standard

(minimal)

References JSR 317 (http://jcp.org/en/jsr/detail?id=317)

ProJPA 2 Mastering the Java™ Persistence API by Mike Keith and Merrick Schincariol

Beginning Java™ EE 6 Platform with GlassFish™ 3 by Antonio Goncalves

http://www.infoq.com/presentations/whats-new-and-exciting-in-jpa-20

http://en.wikibooks.org/wiki/Java_Persistence/What_is_new_in_JPA_2.0%3F

http://wiki.eclipse.org/EclipseLink/Examples/JPA#JPA_2.0

http://www.developer.com/features/article.php/3892261/JPA-20-Cache-Vs-Hibernate-Cache-Differences-in-Approach.htm

Thank you