Servlet 2.3 Filter that binds a Hibernate Session to the thread for the entire processing of the request. Intended for the "Open Session in View" pattern, i.e. to allow for lazy loading in web views despite the original transactions already being completed.
This filter makes Hibernate Sessions available via the current thread, which will be autodetected by transaction managers. It is suitable for service layer transactions via {@link org.springframework.orm.hibernate3.HibernateTransactionManager}or {@link org.springframework.transaction.jta.JtaTransactionManager} as wellas for non-transactional execution (if configured appropriately).
NOTE: This filter will by default not flush the Hibernate Session, with the flush mode set to FlushMode.NEVER
. It assumes to be used in combination with service layer transactions that care for the flushing: The active transaction manager will temporarily change the flush mode to FlushMode.AUTO
during a read-write transaction, with the flush mode reset to FlushMode.NEVER
at the end of each transaction. If you intend to use this filter without transactions, consider changing the default flush mode (through the "flushMode" property).
WARNING: Applying this filter to existing logic can cause issues that have not appeared before, through the use of a single Hibernate Session for the processing of an entire request. In particular, the reassociation of persistent objects with a Hibernate Session has to occur at the very beginning of request processing, to avoid clashes with already loaded instances of the same objects.
Alternatively, turn this filter into deferred close mode, by specifying "singleSession"="false": It will not use a single session per request then, but rather let each data access operation or transaction use its own session (like without Open Session in View). Each of those sessions will be registered for deferred close, though, actually processed at request completion.
A single session per request allows for most efficient first-level caching, but can cause side effects, for example on saveOrUpdate
or when continuing after a rolled-back transaction. The deferred close strategy is as safe as no Open Session in View in that respect, while still allowing for lazy loading in views (but not providing a first-level cache for the entire request).
Looks up the SessionFactory in Spring's root web application context. Supports a "sessionFactoryBeanName" filter init-param in web.xml
; the default bean name is "sessionFactory". Looks up the SessionFactory on each request, to avoid initialization order issues (when using ContextLoaderServlet, the root application context will get initialized after this filter).
@author Juergen Hoeller
@since 1.2
@see #setSingleSession
@see #setFlushMode
@see #lookupSessionFactory
@see OpenSessionInViewInterceptor
@see org.springframework.orm.hibernate3.HibernateInterceptor
@see org.springframework.orm.hibernate3.HibernateTransactionManager
@see org.springframework.orm.hibernate3.SessionFactoryUtils#getSession
@see org.springframework.transaction.support.TransactionSynchronizationManager