This document summarizes the new features of JPA 2.0 as defined in JSR 317. Key additions include expanded object-relational mappings, improved domain modeling capabilities, enhancements to the Java Persistence query language including a Criteria API, standardization of configuration hints, support for validation via JSR 303, and second level caching.

1. „JPA 2.0“
New Features of JSR 317

2. JSR 317: Java Persistence API
• Specification Lead:
Linda DeMichiel, Sun Microsystems, Inc.
• Expert Group:
Adobe Systems Inc., akquinet tech@spree, BEA Systems, Adam Bien,
DataDirect Technologies, Ericsson AB, Antonio Goncalves, IBM, Chris Maki,
Oracle, OW2, Pramati Technologies, RedHat, SAP AG Sun Microsystems
Inc., Sybase, TmaxSoft Inc., VMWare
• Referenzimplemention:
EclipseLink 2.x, www.eclipse.org/eclipselink
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3. Goals
• Expanded O/R mappings
• Improved domain modeling capabilities
• Additions to the Java Persistence query language
• An API for criteria queries
• Standardization of configuration hints
• Additional contracts for detached entities and extended persistence
contexts
• Support for validation via integration with the work of JSR 303
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4. @OneToMany / @ManyToOne
@OneToMany
@JoinColumn(name = "ID")
private List<Editor> editors;
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5. @ElementCollection
@ElementCollection
private Set<String> websites = new HashSet();
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6. @OrderColumn
@OrderColumn(name="ED_ORDER")
private List<Editor> editors;
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7. @MapKeyJoinColumn
@JoinTable(name="ADRESSESS",
joinColumns=
@JoinColumn(name="AUTORID"),
inverseJoinColumns=@JoinColumn(name="CONTACTID"))
@MapKeyJoinColumn(name="ADRESSID")
Map<Adress, Contactdetails> allAdressess;
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8. @Embeddable
@Embedded
PhoneNumber number;
@ManyToOne
PhoneServiceProvider provider;
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9. @Access
@Entity @Access(FIELD)
public class PhoneNumber {
...
@Transient String localnumber;
@Access(PROPERTY)
protected double getInternationalNumber(Locale locale) {
return convertToIntNumber(localnumber);
}
...
}
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10. Combined Primary Keys
@Entity
@IdClass(ArticlePK.class)
public class Article {
@Id Long id;
@Id @ManyToOne Magazine magazine;
@Id @ManyToOne Author author;
}
public class ArticlePK {
Long id;
Long magazine;
Long author;
}
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11. Criteria API I
// create / inject EntityManager
EntityManager em = ...;
// build Criteria Query
CriteriaBuilder qb = em.getCriteriaBuilder();
CriteriaQuery cq = qb.createQuery();
Root<Author> autor = cq.from(Author.class);
cq.select(author);
// execute Criteria Query
Query query = em.createQuery(cq);
List result = query.getResultList();
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12. Criteria API II
Root autor = cq.from(Author.class);
cq.where(qb.equal(author.get("name"), name));
cq.select(autor);
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13. Metamodel API
@Entity public class Customer {
@Id int custId;
String name;
...
@OneToMany(mappedBy="customer") Set<Order> orders;
...
}
import javax.persistence.metamodel.*;
@TypesafeMetamodel
public class Customer_ {
public static volatile Attribute<Customer, Integer> custId;
public static volatile Attribute<Customer, String> name;
public static volatile Set<Customer, Order> orders;
...
}
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14. Metamodel API + Criteria API
cq.where(qb.equal(autor.get(Autor_.name), "name"));
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15. Bean Validation (JSR-303)
@Entity
public class Autor implements Serializable {
[…]
@NotNull
@Size(max=30)
private String name;
[…]
}
•@NotNull
•@Size.max
•@Digits
•@Min / @Max
•@Future / @Past
•@Size
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16. LockModeTypes
.READ => LockModeType.OPTIMISTIC
.WRITE => LockModeType.OPTIMISTIC_FORCE_INCREMENT
NEW!:
LockModeType.PESSIMISTIC_READ (Repeatable Read)
LockModeType.PESSIMISTIC_WRITE (Serialized)
LockModeType.PESSIMISTIC_FORCE_INCREMENT
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17. JPQL Enhancements
• Timestamp
• Non-polymorphic Queries
• Collection Paramters in IN Expression
• Ordered List Index
• CASE Statement
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18. Second Level Cache
public interface Cache {
boolean contains(Class clz, Object primaryKey);
void evict(Class clz, Object primaryKey);
void evict(Class clz);
void evictAll();
}
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19. Links und Informationen
• http://blog.eisele.net/
• http://blogs.sun.com/ldemichiel/
• http://www.jcp.org/en/jsr/detail?id=317
• http://www.eclipse.org/eclipselink
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