org.dellroad.stuff.vaadin
Class ContextApplication

java.lang.Object
  com.vaadin.Application
      org.dellroad.stuff.vaadin.ContextApplication

All Implemented Interfaces:

HttpServletRequestListener, Terminal.ErrorListener, URIHandler, Serializable

Direct Known Subclasses:

SpringContextApplication

public abstract class ContextApplication
extends Application
implements HttpServletRequestListener

Application subclass that provides some basic infrastructure for Vaadin applications:

• Access to the currently running Vaadin application (via a get())
• A way to safely interact with a Vaadin application from a background thread (via invoke(java.lang.Runnable))
• Support for Vaadin application close event notifications
• Displays any exceptions thrown in an overlay error window
• A Logger to use

Since:

1.0.134

See Also:

Serialized Form

Nested Class Summary

static class	ContextApplication.CloseEvent Event delivered to listeners when a ContextApplication is closed.
static interface	ContextApplication.CloseListener Implemented by listeners that wish to be notified when a ContextApplication is closed.

Nested classes/interfaces inherited from class com.vaadin.Application

Application.ApplicationError, Application.CustomizedSystemMessages, Application.SystemMessages, Application.UserChangeEvent, Application.UserChangeListener, Application.WindowAttachEvent, Application.WindowAttachListener, Application.WindowDetachEvent, Application.WindowDetachListener

Nested classes/interfaces inherited from interface com.vaadin.terminal.URIHandler

URIHandler.ErrorEvent

Field Summary

static int	DEFAULT_NOTIFICATION_DELAY Default notification linger time for error notifications (in milliseconds): Value is 30000ms.
protected Logger	log

Constructor Summary

ContextApplication()

Method Summary

void	addListener(ContextApplication.CloseListener listener) Add a ContextApplication.CloseListener to be notified when this instance is closed.
void	close() Close this instance.
static ContextApplication	currentApplication() Get the ContextApplication instance associated with the current thread.
static <A extends ContextApplication> A	currentApplication(Class<A> type) Get the ContextApplication associated with the current thread, cast to the desired type.
static HttpServletRequest	currentRequest() Get the HttpServletRequest associated with the current thread.
static HttpServletResponse	currentResponse() Get the HttpServletResponse associated with the current thread.
protected void	doOnRequestEnd(HttpServletRequest request, HttpServletResponse response) Sub-class hook for handling the end of a request.
protected void	doOnRequestStart(HttpServletRequest request, HttpServletResponse response) Sub-class hook for handling the start of a request.
static ContextApplication	get() Get the ContextApplication instance associated with the current thread or throw an exception if there is none.
static <A extends ContextApplication> A	get(Class<A> type) Get the ContextApplication instance associated with the current thread, cast to the desired type, or throw an exception if there is none.
protected String	getErrorMessage(Throwable t) Convert an exception into a displayable error message.
protected int	getNotificationDelay() Get the notification linger time for error notifications (in milliseconds).
void	init() Initialize the application.
protected abstract void	initApplication() Initialize the application.
void	invoke(Runnable action) Set this instance as the "current application" (if not set already) while invoking the given callback.
Future<?>	invokeLater(Runnable action) Set this instance as the "current application" and invoke the given callback from within another thread.
void	onRequestEnd(HttpServletRequest request, HttpServletResponse response) Handle the end of a request.
void	onRequestStart(HttpServletRequest request, HttpServletResponse response) Handle the start of a request.
void	removeListener(ContextApplication.CloseListener listener) Remove a ContextApplication.CloseListener.
void	showError(String title, String description) Display an error message to the user.
void	showError(String title, Throwable t) Display an error message to the user caused by an exception.
void	terminalError(Terminal.ErrorEvent event) Handle an uncaugt exception thrown by a Vaadin HTTP request.

Methods inherited from class com.vaadin.Application

addListener, addListener, addListener, addResource, addWindow, getContext, getErrorHandler, getLocale, getLogoutURL, getMainWindow, getProperty, getPropertyNames, getRelativeLocation, getSystemMessages, getTheme, getURL, getUser, getVersion, getWindow, getWindows, handleURI, isRunning, removeListener, removeListener, removeListener, removeResource, removeWindow, setErrorHandler, setLocale, setLogoutURL, setMainWindow, setTheme, setUser, start

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_NOTIFICATION_DELAY

public static final int DEFAULT_NOTIFICATION_DELAY

Default notification linger time for error notifications (in milliseconds): Value is 30000ms.

See Also:

Constant Field Values

log

protected final Logger log

Constructor Detail

ContextApplication

public ContextApplication()

Method Detail

init

public final void init()

Initialize the application.

The implementation in ContextApplication delegates to initApplication().

Specified by:

init in class Application

initApplication

protected abstract void initApplication()

Initialize the application. Sub-classes of ContextApplication must implement this method.

terminalError

public void terminalError(Terminal.ErrorEvent event)

Handle an uncaugt exception thrown by a Vaadin HTTP request.

The implementation in ContextApplication logs the error and displays in on the user's screen via showError(String, Throwable).

Specified by:

terminalError in interface Terminal.ErrorListener

Overrides:

terminalError in class Application

showError

public void showError(String title,
                      String description)

Display an error message to the user.

showError

public void showError(String title,
                      Throwable t)

Display an error message to the user caused by an exception.

getNotificationDelay

protected int getNotificationDelay()

Get the notification linger time for error notifications (in milliseconds).

The implementation in ContextApplication returns DEFAULT_NOTIFICATION_DELAY.

getErrorMessage

protected String getErrorMessage(Throwable t)

Convert an exception into a displayable error message.

invoke

public void invoke(Runnable action)

Set this instance as the "current application" (if not set already) while invoking the given callback.

This method is useful for situations in which non-Vaadin threads need to call into Vaadin code that expects to successfully retrieve the current application via currentApplication().

This method also synchronizes on this ContextApplication instance as required by Vaadin for thread safety.

Parameters:

action - action to perform

Throws:

IllegalStateException - if a different ContextApplication is already set as the current application associated with the current thread

See Also:

invokeLater()

invokeLater

public Future<?> invokeLater(Runnable action)

Set this instance as the "current application" and invoke the given callback from within another thread.

This method functions like invoke() except that action will be invoked from within a separate thread dedicated to this application instance. This is useful to reduce Vaadin application lock contention, by performing Vaadin-related actions in a separate, dedicated thread. Actions are executed in the order they are given to this method.

The returned Future's get() method will return null upon successful completion. This method itself always returns immediately.

Parameters:

action - action to perform

Returns:

a Future representing the pending results of action

Throws:

IllegalStateException - if this instance is not initialized or has been closed

See Also:

invoke()

onRequestStart

public final void onRequestStart(HttpServletRequest request,
                                 HttpServletResponse response)

Handle the start of a request.

The implementation in ContextApplication delegates to doOnRequestStart(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse).

Specified by:

onRequestStart in interface HttpServletRequestListener

onRequestEnd

public final void onRequestEnd(HttpServletRequest request,
                               HttpServletResponse response)

Handle the end of a request.

The implementation in ContextApplication delegates to doOnRequestEnd(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse).

Specified by:

onRequestEnd in interface HttpServletRequestListener

doOnRequestStart

protected void doOnRequestStart(HttpServletRequest request,
                                HttpServletResponse response)

Sub-class hook for handling the start of a request. This method is invoked by onRequestStart(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse).

The implementation in ContextApplication does nothing. Subclasses should override as necessary.

doOnRequestEnd

protected void doOnRequestEnd(HttpServletRequest request,
                              HttpServletResponse response)

Sub-class hook for handling the end of a request. This method is invoked by onRequestEnd(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse).

The implementation in ContextApplication does nothing. Subclasses should override as necessary.

currentApplication

public static ContextApplication currentApplication()

Get the ContextApplication instance associated with the current thread.

If the current thread is handling a Vaadin HTTP request that is executing within an ContextApplication instance, or is executing within invoke(java.lang.Runnable), then this method will return the associated ContextApplication.

Returns:

the ContextApplication associated with the current thread, or null if the current thread is not servicing a Vaadin web request or the current Vaadin Application is not an ContextApplication

See Also:

invoke(java.lang.Runnable)

currentApplication

public static <A extends ContextApplication> A currentApplication(Class<A> type)

Get the ContextApplication associated with the current thread, cast to the desired type.

Parameters:

type - expected application type

Returns:

the ContextApplication associated with the current thread

Throws:

ClassCastException - if the current application is not assignable to type

See Also:

currentApplication()

get

public static ContextApplication get()

Get the ContextApplication instance associated with the current thread or throw an exception if there is none.

If the current thread is handling a Vaadin web request that is executing within an ContextApplication instance, or is executing within invoke(java.lang.Runnable), then this method will return the associated ContextApplication. Otherwise, an exception is thrown.

Returns:

the ContextApplication associated with the current thread

Throws:

IllegalStateException - if the current thread is not servicing a Vaadin web request or the current Vaadin Application is not an ContextApplication

get

public static <A extends ContextApplication> A get(Class<A> type)

Get the ContextApplication instance associated with the current thread, cast to the desired type, or throw an exception if there is none.

Parameters:

type - expected application type

Returns:

the ContextApplication associated with the current thread

Throws:

IllegalStateException - if the current ContextApplication is not found

ClassCastException - if the current application is not assignable to type

See Also:

get()

currentRequest

public static HttpServletRequest currentRequest()

Get the HttpServletRequest associated with the current thread.

If the current thread is handling a Vaadin web request for an instance of this class, this method will return the associated HttpServletRequest.

Returns:

the HttpServletRequest associated with the current thread, or null if the current thread is not servicing a Vaadin web request or the current Vaadin Application is not an instance of this class

currentResponse

public static HttpServletResponse currentResponse()

Get the HttpServletResponse associated with the current thread.

If the current thread is handling a Vaadin web request for an instance of this class, this method will return the associated HttpServletResponse.

Returns:

the HttpServletResponse associated with the current thread, or null if the current thread is not servicing a Vaadin web request or the current Vaadin Application is not an instance of this class

close

public void close()

Close this instance.

The implementation in ContextApplication first delegates to the superclass and then notifies any registered ContextApplication.CloseListeners.

Overrides:

close in class Application

addListener

public void addListener(ContextApplication.CloseListener listener)

Add a ContextApplication.CloseListener to be notified when this instance is closed.

removeListener

public void removeListener(ContextApplication.CloseListener listener)

Remove a ContextApplication.CloseListener.