Web hosting domains - APPENDIX C n HIBERNATE AND SPRING 305 n
APPENDIX C n HIBERNATE AND SPRING 305 n HIBERNATE AND SPRING 305 Table C-1. The Core HibernateTemplate Methods Method Description bulkUpdate() Performs a bulk update or delete on the database, according to the provided HQL query and entities contains() Determines whether the given object exists as an entity in the database delete() Deletes an entity from the database find() Carries out an HQL query get() Obtains an entity by its id (primary key) persist() Saves an entity to the database refresh() Refreshes an entity from the database save() Saves an entity to the database saveOrUpdate() Saves an entity to the database or updates it as appropriate update() Updates an entity in the database When a more complex set of operations is required than can be achieved in a single line, the execute()method is used to invoke an instance of HibernateCallback. Our example application uses HibernateCallbackto implement its createArticle() method. This is shown in Listing C-10. Listing C-10. Invoking a HibernateCallback Object from the Template s execute() Method public Paper createArticle(final Integer paperId,final Article article) { HibernateCallback callback = new HibernateCallback() { public Object doInHibernate(Session session) { Paper paper = (Paper)session.get(Paper.class,paperId); paper.addArticle(article); session.update(paper); return paper; } }; return (Paper)getHibernateTemplate().execute(callback); } Although this allows us to invoke more complex code from the HibernateTemplate class, and HibernateTemplate obviates the need for specific management of the session, it doesn t make the implementation particularly terse, and probably makes it slightly harder to understand. Listing C-11 shows how the same method can be implemented without using HibernateTemplate.
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