1. Hibernate filter is used to give a definition condition in xml mapping files.
2. Ever session want to use it must enable the filter with name first.
3. filter is defined in xml with elment <filter-def> under <hibernate-mapping>, used <filter> element under <class> element.
4. give certain sql condition attribute either in <filter-def> or <filter>.
5. Support value to filter parameters in application.
The main purpose is to support global filter.