JPA 2.x what's new (edit)

JPA 2 (JSR 317) is a superset of JPA 1 and part of Java EE6. Added features include:

• Entities
• mixing of field and getter method annotations
• JSR 303 validation
  
• Relations
• unidirectional OneToMany
• use JoinTable for all relation cardinalities
• Automatic actions upon Entity changes
• CascadeType.DETACH
• orphanRemoval: delete an orphan Entity if its relation to its parent Entity is broken
• Collections
• Support for mapping collections of Basic and Embeddable types (@ElementCollection)
• Map keys and values can both be Basic, Embeddable and Entity types
• Embeddables
• Can be nested
• Can have attributes with relations
• Can inherit from a MappedSuperclass
• Ordering
• @OrderBy: determine order in which elements of List attributes are loaded
• @OrderColumn: support for preserving List order in the database using an OrderColumn
• Queries
• TypedQuery <T>
• Criteria API
• metamodel generation
• JPQL
• functions and operations in SELECT clause
• COALESCE function (returns first non null argument)
• TYPE function: get class of Entity to compare with literal
• CASE expression
• KEY, VALUE, and ENTRY keywords for map operations
• use of enums
• enum and temporal literals
• Locking
• pessimistic locking support
• lock mode arguments in EntityManager methods
• Cache API

JPA 2 is implemented in Hibernate 3.5+

JPA 2.1 (JSR 338) is part of Java EE 7. Added features include:

• StoredProcedureQuery

  StoredProcedureQuery proc = em.createStoredProcedureQuery("squareRoot");
  proc.registerStoredProcedureParameter("square", Double.class, ParameterMode.IN);
  proc.registerStoredProcedureParameter("root", Double.class, ParameterMode.OUT);
  proc.setParameter("square", 338.0);
  proc.execute();
  Double result = (Double)storedProcedure.getOutputParameterValue("root");

• @Converter/@Convert: write custom code to convert java data to/from database data
• JPQL 
• selectively  access  entity subclasses: TREAT (relation.parentEntityAttribute AS  childEntity)
• support for predefined and user defined database functions: FUNCTION(name,args...)

          WHERE FUNCTION (isAllowed, theater.movie, user.age)

• update and delete using the Criteria API
• Standardised schema generation properties 
• Entity Graphs allow runtime control over which parts of an entity are fetched. Here's an example:

@Entity
@NamedEntityGraph(name="withBids", attributeNodes={@NamedAttributeNode("bids")})
public class Auction
{...}

• The Auction above has bids that are normally lazily loaded.
• Using the entity graph you can ask for a variant where the bids are eagerly loaded:

Properties prop = new Properties();
prop.put("javax.persistence.loadgraph", em.getEntityGraph("withBids"););
Auction eagerBids= em.find(Auction.class, auction_id, prop); 

•  In addition to declaring the graph with annotations, you can construct it at runtime with an API
• The graph can also be set as a hint to a query

JPA 2.1 is implemented in Hibernate 4.3+