org.dellroad.stuff.vaadin7

Class VaadinApplication

java.lang.Object

org.dellroad.stuff.vaadin7.VaadinApplication

All Implemented Interfaces:

Serializable

public class VaadinApplication
extends Object
implements Serializable

A globally accessible "Vaadin application" singleton.

At most one instance is associated with each VaadinSession (attempting to create more than one will result in an exception). This singleton instance is then always accessible from any Vaadin thread via get().

Although this class does not require Spring, the singleton instance can be declared as a bean in the Spring XML application context created by a SpringVaadinSessionListener, which allows other beans and widgets in the Vaadin application context to autowire it and have access to the methods provided here:

  <bean class="org.dellroad.stuff.vaadin7.VaadinApplication"/>
 

If your VaadinApplication instance allocates any resources on startup, be sure to configure it so that it cleans them up on application context shutdown, for example, by specifying destroy-method="...".

If you are in a clustered environment and are subclassing this class, scope="session" is recommended; without it, there will be one instance per server+session rather than one unique instance per session. Of course, whether that matters depends on the semantics of the subclass fields. In any case, be aware that no instance will exist in session until the application context is refreshed.

Note: using scope="session" requires adding a <listener> clause registering Spring's RequestContextListener in your web.xml.

If this class is subclassed, additional application-specific fields and methods can be supplied to the entire application via the same mechanism. Subclasses can override init() for any application-specific initialization.

Note: the singleton instance of this class is stored in the Vaadin session and is Serializable. Therefore, in a clustered environment, subclasses must be prepared to handle (de)serialization. Also, avoid declaring fields that reference this class in non-session-scope beans; instead, use VaadinApplication.get().

See Also:

SpringVaadinServlet, SpringVaadinSessionListener, VaadinService, Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected Logger	log

Constructor Summary

Constructors

Constructor and Description
VaadinApplication() Convenience constructor.
VaadinApplication(VaadinSession session) Primary Constructor.

Method Summary

Modifier and Type	Method and Description
void	addSessionDestroyListener(SessionDestroyListener listener) Register for a notification when the VaadinSession is closed, without creating a memory leak.
void	close() Close the VaadinSession associated with this instance.
static VaadinApplication	get() Get the singleton VaadinApplication instance associated with the current VaadinSession.
static <T extends VaadinApplication> T	get(Class<T> clazz) Get the singleton instance of the specified class associated with the current VaadinSession.
static <T extends VaadinApplication> T	get(VaadinSession session, Class<T> clazz) Get the singleton instance of the specified class associated with the given session.
VaadinSession	getSession() Get the VaadinSession associated with this instance.
protected void	init() Perform any further initialization at construction time.
void	invoke(Runnable action) Peform some action while holding the lock of the VaadinSession associated with this instance.
Future<Void>	invokeLater(Runnable action) Peform some action asynchronously while holding the lock of the VaadinSession associated with this instance.
void	removeSessionDestroyListener(SessionDestroyListener listener) Remove a listener added via addSessionDestroyListener().

Methods inherited from class java.lang.Object

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

Field Detail

log

protected transient Logger log

Constructor Detail

VaadinApplication

public VaadinApplication()

Convenience constructor. Equivalent to:

VaadinApplication(VaadinUtil.getCurrentSession())

Throws:

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

IllegalStateException - if there is already a VaadinApplication instance associated with the current session

VaadinApplication

public VaadinApplication(VaadinSession session)

Primary Constructor.

Parameters:

session - the session with which this instance should be associated

Throws:

IllegalArgumentException - if session is null

IllegalStateException - if there is already a VaadinApplication instance associated with session

Method Detail

init

protected void init()

Perform any further initialization at construction time.

The implementation in VaadinApplication does nothing. Subclasses may override as desired.

getSession

public VaadinSession getSession()

Get the VaadinSession associated with this instance.

Returns:

associated VaadinSession, never null

close

public void close()

Close the VaadinSession associated with this instance. After invoking this method, the caller would normally ensure that no further references to this instance remain so that it and the associated VaadinSession can be freed.

The implementation in VaadinApplication just delegates to VaadinSession.close().

get

public static VaadinApplication get()

Get the singleton VaadinApplication instance associated with the current VaadinSession.

This is a convenience method, equivalent to:

VaadinApplication.get(VaadinApplication.class)

Returns:

singleton instance for the current Vaadin application, never null

Throws:

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

IllegalStateException - if there is no VaadinApplication instance associated with the current session

get

public static <T extends VaadinApplication> T get(Class<T> clazz)

Get the singleton instance of the specified class associated with the current VaadinSession.

This is a convenience method, equivalent to:

VaadinApplication.get(VaadinUtil.getCurrentSession(), clazz)

Useful for subclasses of VaadinApplication that want to provide their own zero-parameter get() methods.

Type Parameters:

T - application type

Parameters:

clazz - singleton instance type

Returns:

singleton instance of clazz in the session, never null

Throws:

IllegalArgumentException - if clazz is null

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

IllegalStateException - if there is no singleton of type clazz associated with the current session

get

public static <T extends VaadinApplication> T get(VaadinSession session,
                                                  Class<T> clazz)

Get the singleton instance of the specified class associated with the given session.

Type Parameters:

T - application type

Parameters:

session - Vaadin session

clazz - singleton instance type

Returns:

singleton instance of clazz in the session, never null

Throws:

IllegalArgumentException - if session is null

IllegalArgumentException - if clazz is null

IllegalStateException - if there is no singleton of type clazz associated with the session

invoke

public void invoke(Runnable action)

Peform some action while holding the lock of the VaadinSession associated with this instance.

This is a convenience method that in turn invokes VaadinUtil.invoke() using the VaadinSession associated with this instance.

Parameters:

action - action to perform

Throws:

IllegalArgumentException - if action is null

See Also:

VaadinUtil.invoke(com.vaadin.server.VaadinSession, java.lang.Runnable)

invokeLater

public Future<Void> invokeLater(Runnable action)

Peform some action asynchronously while holding the lock of the VaadinSession associated with this instance.

This is a convenience method that in turn invokes VaadinUtil.invokeLater() using the VaadinSession associated with this instance.

Parameters:

action - action to perform

Returns:

future for the action

Throws:

IllegalArgumentException - if action is null

See Also:

VaadinUtil.invokeLater(com.vaadin.server.VaadinSession, java.lang.Runnable)

addSessionDestroyListener

public void addSessionDestroyListener(SessionDestroyListener listener)

Register for a notification when the VaadinSession is closed, without creating a memory leak.

This is a convenience method that in turn invokes VaadinUtil.addSessionDestroyListener() using the VaadinSession associated with this instance.

Parameters:

listener - listener for notifications

Throws:

IllegalArgumentException - if listener is null

See Also:

VaadinUtil.addSessionDestroyListener(com.vaadin.server.VaadinSession, com.vaadin.server.SessionDestroyListener)

removeSessionDestroyListener

public void removeSessionDestroyListener(SessionDestroyListener listener)

Remove a listener added via addSessionDestroyListener().

This is a convenience method that in turn invokes VaadinUtil.removeSessionDestroyListener() using the VaadinSession associated with this instance.

Parameters:

listener - listener for notifications

Throws:

IllegalArgumentException - if listener is null

See Also:

VaadinUtil.removeSessionDestroyListener(com.vaadin.server.VaadinSession, com.vaadin.server.SessionDestroyListener)