Java Reference
In-Depth Information
Hibernate 2 provided a number of aids to the generation of POJOs, mapping files, and
database schemas. Hibernate 3 has started a process of migrating to external support for these
processes. Where these tools are retained, they can be found in the
org.hibernate.tool
pack-
age and its subpackages. For example, previously a facility provided by the
CodeGenerator
class
to generate DDL from your mappings existed in Hibernate 2. This is still provided in Hibernate
3, but the fully qualified name of the
SchemaExport
class is now
org.hibernate.tool.hbm2ddl.
SchemaExport
—but even though the tool still exists, the generation of mapping files from
POJOs in Hibernate 3 would usually be conducted by an Eclipse plug-in, or the Hibernate
Tools Ant tasks. See Appendix B for an extensive discussion of the use of the Eclipse plug-ins
and Ant tasks.
Changes with Java 5
The latest release of Java introduced some pretty substantial changes to the language. It also
introduced some incompatibilities with the previous class file format.
The only significant addition to Hibernate 3 that relies directly upon a Java 5-specific
feature is the annotations support. Otherwise, a 1.4 JVM will work fine. In fact, it is even possible
to build Hibernate 3 for a 1.3 JVM, although a suitable binary version is no longer distributed.
The use of annotation-based mapping in Hibernate 3 is discussed in depth in Chapter 6.
Summary
In this appendix, we examined some of the changes that have been introduced with Hibernate
3, and showed how code written for Hibernate 2 can be run in parallel with Hibernate 3, or be
readily adapted to run directly under Hibernate 3.
