Does anybody know of a good list of what is new in JPA 2? Not what is new with Hibernate/TopLink in the version that supports JPA 2 but what is new in the actual spec.
The link mentioned in the accepted answer doesn't say anything about the second level cache so I decided to post a quick list to summarize "What's new in JPA 2.0 (JSR-317)":
- Standard properties for
persistence.xml- E.g.javax.persistence.jdbc.driver, etc instead of persistence provider specific properties. - Mixed Access Type -
PROPERTYandFIELDaccess type can be mixed in a hierarchy and combined in a single class. - Derived Identifiers - Identifiers can be derived from relationships.
@ElementCollection,@OrderColumn- For better collection support.- Unidirectional
@OneToMany/@OneToOne- For expanded mappings. - Shared Cache API - Second level caching in JPA, yeah!
- Locking - Support for pessimistic locking added.
- Enhanced JP QL - Timestamp literals, non-polymorphic queries, collection parameter in IN expression, ordered list index, CASE statement.
- Expression and Criteria API -
QueryBuilderandCriteriaQueryfor programmatic construction of type-safe queries. - API additions - Additional API on
EntityManager(supported properties,detachmethod, etc) andQuery(query hints). - Validation - Transparent support of Bean Validation (JSR-303) if provider is present. (Validation is optional, the JPA 2.0 spec does not require a Bean Validation implementation).
Regarding this question, this link is maybe not 100% precise, but it's a very good source of information to start from.
来源：https://stackoverflow.com/questions/2435253/a-concise-clear-list-of-what-is-new-in-jpa2