org.dellroad.stuff.vaadin7

Class SpringVaadinSessionListener

java.lang.Object

org.dellroad.stuff.vaadin7.SpringVaadinSessionListener

All Implemented Interfaces:

SessionDestroyListener, SessionInitListener, Serializable

public class SpringVaadinSessionListener
extends Object
implements SessionInitListener, SessionDestroyListener

Manages an associated Spring WebApplicationContext with each VaadinSession (aka, "Vaadin application"). Typically created implicitly via SpringVaadinServlet.

Overview

In Vaadin 7, the VaadinSession object holds the state associated with each client browser connection to a Vaadin servlet. For consistency with older versions of Vaadin, we'll call this a "Vaadin application" instance. This class gives each Vaadin such "Vaadin application" instance its own Spring application context, and all such application contexts share the same parent context, which is the one associated with the overal servlet web context (i.e., the one created by Spring's ContextLoaderListener). This setup is analogous to how Spring's DispatcherServlet creates per-servlet application contexts that are children of the overall servlet web context.

This class is implemented as a SessionInitListener and SessionDestroyListener on the servlet's VaadinService object. In turn, the Spring context is created when a new Vaadin application instance is initialized, and destroyed when it is closed. To use this class, use the SpringVaadinServlet in place of the usual VaadinServlet in web.xml.

Accessing the Spring Context

The getApplicationContext() method provides access to the application context. Alternately, use @VaadinConfigurable (see below) and implement ApplicationContextAware, etc. Invoking configureBean() at any time will configure a bean manually.

Exposing the Vaadin Session

The VaadinSession instance representing the "Vaadin application" can be exposed in the associated Spring application context and therefore made available for autowiring, etc. Simply add a bean definition that invokes VaadinUtil.getCurrentSession():

  <bean id="vaadinSession" class="org.dellroad.stuff.vaadin7.VaadinUtil" factory-method="getCurrentSession"/>
 

This bean can then be autowired into application-specific "backend" beans, allowing them to use e.g. VaadinUtil.invoke(), which performs the locking necessary to avoid race conditions. But see also VaadinApplication for a convenience class that makes this process a little cleaner.

@VaadinConfigurable Beans

It is also possible to configure beans outside of this application context using AOP, so that any invocation of new FooBar(), where the class FooBar is marked @VaadinConfigurable, will automagically cause the new FooBar object to be configured by the application context associated with the currently running Vaadin application. In effect, this does for Vaadin application beans what Spring's @Configurable does for regular servlet context-wide beans.

Note however that Spring destroy methods will not be invoked on application close for these beans, since their lifecycle is controlled outside of the Spring application context (this is also the case with @Configurable beans). Instead, these beans can themselves register as a SessionDestroyListener for shutdown notification; but see VaadinUtil.addSessionDestroyListener() for a memory-leak free method for doing this.

Serialization and Clustering

Instances are serializable; on deserialization the ConfigurableWebApplicationContext associated with the VaadinSession is refreshed; therefore, the ConfigurableWebApplicationContext is not itself stored in the HTTP session by this class. This is consistent with the way normal Spring application contexts ususally work across clustered servers.

However, any session-scope beans should work as expected. So while this class associates an application context with each VaadinSession, when sessions are shared across multiple servers in a clustered environment, there will actually be a separate application contexts per server. Beans that must truly be "session wide" should be declared scope="session" as you normally would.

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

See Also:

VaadinConfigurable, SpringVaadinServlet, VaadinApplication, VaadinService, VaadinSession, Serialized Form

Constructor Summary

Constructors

Constructor and Description
SpringVaadinSessionListener(String applicationName, String configLocation) Constructor.

Method Summary

Modifier and Type	Method and Description
static void	configureBean(Object bean) Configure the given bean using the Spring application context associated with the current thread's VaadinSession.
static ConfigurableWebApplicationContext	getApplicationContext() Get the Spring application context associated with the current thread's VaadinSession.
static ConfigurableWebApplicationContext	getApplicationContext(VaadinSession session) Get the Spring application context associated with the given VaadinSession.
String	getApplicationName() Get the name of this Vaadin application.
protected void	loadContext(VaadinSession session, VaadinRequest request) Load the Spring application context.
void	sessionDestroy(SessionDestroyEvent event)
void	sessionInit(SessionInitEvent event)

Methods inherited from class java.lang.Object

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

Constructor Detail

SpringVaadinSessionListener

public SpringVaadinSessionListener(String applicationName,
                                   String configLocation)

Constructor.

Parameters:

applicationName - Vaadin application name

configLocation - XML application context config file location(s), or null for the default /WEB-INF/ServletName.xml, where ServletName is the value of applicationName

Throws:

IllegalArgumentException - if applicationName is null

Method Detail

getApplicationName

public String getApplicationName()

Get the name of this Vaadin application.

Returns:

application name

getApplicationContext

public static ConfigurableWebApplicationContext getApplicationContext(VaadinSession session)

Get the Spring application context associated with the given VaadinSession.

Parameters:

session - Vaadin session

Returns:

Spring application context, or null if none is found

Throws:

IllegalArgumentException - if session is null

getApplicationContext

public static ConfigurableWebApplicationContext getApplicationContext()

Get the Spring application context associated with the current thread's VaadinSession.

Returns:

Spring application context, never null

Throws:

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

IllegalStateException - if there is no Spring application context associated with the VaadinSession

configureBean

public static void configureBean(Object bean)

Configure the given bean using the Spring application context associated with the current thread's VaadinSession.

Parameters:

bean - Java bean to configure

Throws:

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

IllegalStateException - if there is no Spring application context associated with the VaadinSession

sessionInit

public void sessionInit(SessionInitEvent event)
                 throws ServiceException

Specified by:

sessionInit in interface SessionInitListener

Throws:

ServiceException

loadContext

protected void loadContext(VaadinSession session,
                           VaadinRequest request)

Load the Spring application context.

This method expects that session is already locked.

Parameters:

session - the Vaadin application session

request - the triggering request

sessionDestroy

public void sessionDestroy(SessionDestroyEvent event)

Specified by:

sessionDestroy in interface SessionDestroyListener