Package org.dellroad.stuff.vaadin8

Class VaadinUtil

java.lang.Object

org.dellroad.stuff.vaadin8.VaadinUtil

public final class VaadinUtil
extends Object

Miscellaneous utility methods.

Method Summary

Modifier and Type	Method	Description
static Registration	addSessionDestroyListener(VaadinSession session, SessionDestroyListener listener)	Register for a notification when the VaadinSession is closed, without creating a memory leak.
static void	assertSession(VaadinSession session)	Verify that we are running in the context of the given session and holding the session's lock.
static VaadinRequest	getCurrentRequest()	Get the VaadinRequest associated with the current thread.
static VaadinSession	getCurrentSession()	Get the VaadinSession associated with the current thread.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

assertSession

public static void assertSession(VaadinSession session)

Verify that we are running in the context of the given session and holding the session's lock. This method can be used by any code that manipulates Vaadin state to assert that the proper Vaadin locking has been performed.

Parameters:

session - session we are supposed to be running with

Throws:

IllegalArgumentException - if session is null

IllegalStateException - if there is no VaadinSession associated with the current thread

IllegalStateException - if the VaadinSession associated with the current thread is not session

IllegalStateException - if the VaadinSession associated with the current thread is not locked

IllegalStateException - if the VaadinSession associated with the current thread is locked by another thread

getCurrentSession

public static VaadinSession getCurrentSession()

Get the VaadinSession associated with the current thread. This is just a wrapper around VaadinSession.getCurrent() that throws an exception instead of returning null when there is no session associated with the current thread.

Returns:

current VaadinSession, never null

Throws:

IllegalStateException - if there is no VaadinSession associated with the current thread

getCurrentRequest

public static VaadinRequest getCurrentRequest()

Get the VaadinRequest associated with the current thread. This is just a wrapper around VaadinService.getCurrentRequest() that throws an exception instead of returning null when there is no request associated with the current thread.

Returns:

current VaadinRequest, never null

Throws:

IllegalStateException - if there is no VaadinRequest associated with the current thread

addSessionDestroyListener

public static Registration addSessionDestroyListener(VaadinSession session,
                                                     SessionDestroyListener listener)

Register for a notification when the VaadinSession is closed, without creating a memory leak. This method is intended to be used by listeners that are themselves part of a Vaadin application.

Explanation: the VaadinSession class does not provide a listener API directly; instead, you must use the VaadinService class. However, registering as a listener on the VaadinService when you are part of a Vaadin application sets you up for a memory leak if you forget to unregister yourself when the notification arrives, because the VaadinService lifetime is longer than the VaadinSession lifetime. This method handles that de-registration for you automatically.

Parameters:

session - Vaadin session

listener - listener for notifications

Returns:

listener registration

Throws:

IllegalArgumentException - if either parameter is null