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This article mainly introduces "what is the Hibernate dynamic model". In the daily operation, I believe many people have doubts about what the Hibernate dynamic model is. The editor consulted all kinds of data and sorted out simple and easy-to-use operation methods. I hope it will be helpful for you to answer the doubts about "what is the Hibernate dynamic model?" Next, please follow the editor to study!

Hibernate dynamic model (Dynamic models)

Note: the following features are currently in the experimental stage and may change in the future.

Runtime persistence entities do not necessarily have to be represented as POJO classes or JavaBean objects. Hibernate also supports dynamic models (using Map's Map at run time) and entity representations like DOM4J's tree model. With this method, you don't have to write the persistence class, just write the mapping file.

Hibernate works in normal POJO mode by default. You can use the configuration option default_entity_mode to set a default entity representation mode for a specific SessionFactory. (see Table 3. 3 "Hibernate configuration Properties". )

The following is an example expressed in Map. First, in the mapping file, you declare entity-name instead of a class name (or as an attachment).

Note: although the association is declared with the target class name, the associated target type can also be a dynamic entity in addition to POJO.

After you set the default entity mode for SessionFactory using dynamic-map, you can use Map's Map at run time.

Session s = openSession (); Transaction tx = s.beginTransaction (); Session s = openSession (); / / Create a customer Map david = new HashMap (); david.put ("name", "David"); / / Create an organization Map foobar = new HashMap (); foobar.put ("name", "Foobar Inc."); / / Link both david.put ("organization", foobar); / / Save both s.save ("Customer", david) S.save ("Organization", foobar); tx.commit (); s.close ()

The advantage of dynamic mapping is that it takes less time to change because the prototype does not need to implement entity classes. However, you cannot do compile-time type checking and may handle a lot of run-time exceptions. Thanks to the Hibernate mapping, it makes it easy to normalize and rationalize the schema of the data base, and allows appropriate domain model implementations to be added later.

The entity representation mode can also be set on a per-Session basis:

Session dynamicSession = pojoSession.getSession (EntityMode.MAP); / / Create a customer Map david = new HashMap (); david.put ("name", "David"); dynamicSession.save ("Customer", david); DynamicSession.flush (); dynamicSession.close ()... / / Continue on pojoSession

Note that the call to getSession () with EntityMode is in the API of Session, not SessionFactory. In this way, the new Session shares underlying JDBC connections, transactions, and other contextual messages. This means that you don't need to call flush () and close () in the second Session, again, handing over the transaction and connection processing to the original unit of work.

At this point, the study of "what is the dynamic model of Hibernate" is over. I hope to be able to solve your doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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