Class Application

java.lang.Object
  com.vaadin.Application

All Implemented Interfaces:

Terminal.ErrorListener, URIHandler, Serializable

public abstract class Application
extends Object
implements URIHandler, Terminal.ErrorListener, Serializable

Base class required for all Vaadin applications. This class provides all the basic services required by Vaadin. These services allow external discovery and manipulation of the user, windows and themes, and starting and stopping the application.

As mentioned, all Vaadin applications must inherit this class. However, this is almost all of what one needs to do to create a fully functional application. The only thing a class inheriting the Application needs to do is implement the init method where it creates the windows it needs to perform its function. Note that all applications must have at least one window: the main window. The first unnamed window constructed by an application automatically becomes the main window which behaves just like other windows with one exception: when accessing windows using URLs the main window corresponds to the application URL whereas other windows correspond to a URL gotten by catenating the window's name to the application URL.

See the class com.vaadin.demo.HelloWorld for a simple example of a fully working application.

Window access. Application provides methods to list, add and remove the windows it contains.

Execution control. This class includes method to start and finish the execution of the application. Being finished means basically that no windows will be available from the application anymore.

Theme selection. The theme selection process allows a theme to be specified at three different levels. When a window's theme needs to be found out, the window itself is queried for a preferred theme. If the window does not prefer a specific theme, the application containing the window is queried. If neither the application prefers a theme, the default theme for the terminal is used. The terminal always defines a default theme.

Since:

3.0

Version:

6.8.18

Author:

Vaadin Ltd.

See Also:

Serialized Form

Nested Class Summary
class	Application.ApplicationError           Application error is an error message defined on the application level.
static class	Application.CustomizedSystemMessages           Contains the system messages used to notify the user about various critical situations that can occur.
static class	Application.SystemMessages           Contains the system messages used to notify the user about various critical situations that can occur.
class	Application.UserChangeEvent            An event that characterizes a change in the current selection.
static interface	Application.UserChangeListener           The UserChangeListener interface for listening application user changes.
class	Application.WindowAttachEvent           Window attach event.
static interface	Application.WindowAttachListener           Window attach listener interface.
class	Application.WindowDetachEvent           Window detach event.
static interface	Application.WindowDetachListener           Window detach listener interface.

 

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

 

Constructor Summary
Application()

 

Method Summary
void	addListener(Application.UserChangeListener listener)           Adds the user change listener.
void	addListener(Application.WindowAttachListener listener)           Adds the window attach listener.
void	addListener(Application.WindowDetachListener listener)           Adds the window detach listener.
void	addResource(ApplicationResource resource)           Adds new resource to the application.
void	addWindow(Window window)           Adds a new window to the application.
void	close()           Ends the Application.
ApplicationContext	getContext()           Gets the application context.
Terminal.ErrorListener	getErrorHandler()           Gets the application error handler.
Locale	getLocale()           Gets the default locale for this application.
String	getLogoutURL()           Returns the URL user is redirected to on application close.
Window	getMainWindow()           Gets the mainWindow of the application.
String	getProperty(String name)           Searches for the property with the specified name in this application.
Enumeration<?>	getPropertyNames()           Returns an enumeration of all the names in this application.
String	getRelativeLocation(ApplicationResource resource)           Deprecated. this method is intended to be used by the terminal only. It may be removed or moved in the future.
static Application.SystemMessages	getSystemMessages()           Gets the SystemMessages for this application.
String	getTheme()           Gets the application's theme.
URL	getURL()           Gets the URL of the application.
Object	getUser()           Gets the user of the application.
String	getVersion()           Override this method to return correct version number of your Application.
Window	getWindow(String name)            Gets a window by name.
Collection<Window>	getWindows()           Gets the set of windows contained by the application.
DownloadStream	handleURI(URL context, String relativeUri)           Deprecated. this method is called be the terminal implementation only and might be removed or moved in the future. Instead of overriding this method, add your URIHandler to a top level Window (eg. getMainWindow().addUriHanler(handler) instead.
abstract  void	init()            Main initializer of the application.
boolean	isRunning()           Tests if the application is running or if it has been finished.
void	removeListener(Application.UserChangeListener listener)           Removes the user change listener.
void	removeListener(Application.WindowAttachListener listener)           Removes the window attach listener.
void	removeListener(Application.WindowDetachListener listener)           Removes the window detach listener.
void	removeResource(ApplicationResource resource)           Removes the resource from the application.
void	removeWindow(Window window)           Removes the specified window from the application.
void	setErrorHandler(Terminal.ErrorListener errorHandler)           Sets the application error handler.
void	setLocale(Locale locale)           Sets the default locale for this application.
void	setLogoutURL(String logoutURL)           Sets the URL user is redirected to on application close.
void	setMainWindow(Window mainWindow)            Sets the mainWindow.
void	setTheme(String theme)           Sets the application's theme.
void	setUser(Object user)            Sets the user of the application instance.
void	start(URL applicationUrl, Properties applicationProperties, ApplicationContext context)           Starts the application on the given URL.
void	terminalError(Terminal.ErrorEvent event)            Invoked by the terminal on any exception that occurs in application and is thrown by the setVariable to the terminal.

 

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Constructor Detail

Application

public Application()

Method Detail

getWindow

public Window getWindow(String name)

Gets a window by name. Returns null if the application is not running or it does not contain a window corresponding to the name.

All windows can be referenced by their names in url http://host:port/foo/bar/ where http://host:port/foo/ is the application url as returned by getURL() and bar is the name of the window.

One should note that this method can, as a side effect create new windows if needed by the application. This can be achieved by overriding the default implementation.

If for some reason user opens another window with same url that is already open, the name is modified by adding a "_N" postfix to the name, where N is a running number starting from 1. One can decide to create another window-object for those windows (recommended) or to discard the postfix. If the user has two browser windows pointing to the same window-object on server, synchronization errors are likely to occur.

If no browser-level windowing is used, all defaults are fine and this method can be left as is. In case browser-level windows are needed, it is recommended to create new window-objects on this method from their names if the super.getWindow() does not find existing windows. See below for implementation example:

        // If we already have the requested window, use it
        Window w = super.getWindow(name);
        if (w == null) {
            // If no window found, create it
            w = new Window(name);
            // set windows name to the one requested
            w.setName(name);
            // add it to this application
            addWindow(w);
            // ensure use of window specific url
            w.open(new ExternalResource(w.getURL().toString()));
            // add some content
            w.addComponent(new Label("Test window"));
        }
        return w;

Note that all returned Window objects must be added to this application instance.

The method should return null if the window does not exists (and is not created as a side-effect) or if the application is not running anymore.

Parameters:

name - the name of the window.

Returns:

the window associated with the given URI or null

addWindow

public void addWindow(Window window)
               throws IllegalArgumentException,
                      NullPointerException

Adds a new window to the application.

This implicitly invokes the Window.setApplication(Application) method.

Note that all application-level windows can be accessed by their names in url http://host:port/foo/bar/ where http://host:port/foo/ is the application url as returned by getURL() and bar is the name of the window. Also note that not all windows should be added to application - one can also add windows inside other windows - these windows show as smaller windows inside those windows.

Parameters:

window - the new Window to add. If the name of the window is null, an unique name is automatically given for the window.

Throws:

IllegalArgumentException - if a window with the same name as the new window already exists in the application.

NullPointerException - if the given Window is null.

removeWindow

public void removeWindow(Window window)

Removes the specified window from the application.

Removing the main window of the Application also sets the main window to null. One must another window to be the main window after this with setMainWindow(Window).

Note that removing window from the application does not close the browser window - the window is only removed from the server-side.

Parameters:

window - the window to be removed.

getUser

public Object getUser()

Gets the user of the application.

Vaadin doesn't define of use user object in any way - it only provides this getter and setter methods for convenience. The user is any object that has been stored to the application with setUser(Object).

Returns:

the User of the application.

setUser

public void setUser(Object user)

Sets the user of the application instance. An application instance may have a user associated to it. This can be set in login procedure or application initialization.

A component performing the user login procedure can assign the user property of the application and make the user object available to other components of the application.

Vaadin doesn't define of use user object in any way - it only provides getter and setter methods for convenience. The user reference stored to the application can be read with getUser().

Parameters:

user - the new user.

getURL

public URL getURL()

Gets the URL of the application.

This is the URL what can be entered to a browser window to start the application. Navigating to the application URL shows the main window ( getMainWindow()) of the application. Note that the main window can also be shown by navigating to the window url ( Window.getURL()).

Returns:

the application's URL.

close

public void close()

Ends the Application.

In effect this will cause the application stop returning any windows when asked. When the application is closed, its state is removed from the session and the browser window is redirected to the application logout url set with setLogoutURL(String). If the logout url has not been set, the browser window is reloaded and the application is restarted.

.

start

public void start(URL applicationUrl,
                  Properties applicationProperties,
                  ApplicationContext context)

Starts the application on the given URL.

This method is called by Vaadin framework when a user navigates to the application. After this call the application corresponds to the given URL and it will return windows when asked for them. There is no need to call this method directly.

Application properties are defined by servlet configuration object ServletConfig and they are overridden by context-wide initialization parameters ServletContext.

Parameters:

applicationUrl - the URL the application should respond to.

applicationProperties - the Application properties as specified by the servlet configuration.

context - the context application will be running in.

isRunning

public boolean isRunning()

Tests if the application is running or if it has been finished.

Application starts running when its start(URL, Properties, ApplicationContext) method has been called and stops when the close() is called.

Returns:

true if the application is running, false if not.

getWindows

public Collection<Window> getWindows()

Gets the set of windows contained by the application.

Note that the returned set of windows can not be modified.

Returns:

the Unmodifiable collection of windows.

init

public abstract void init()

Main initializer of the application. The init method is called by the framework when the application is started, and it should perform whatever initialization operations the application needs, such as creating windows and adding components to them.

getTheme

public String getTheme()

Gets the application's theme. The application's theme is the default theme used by all the windows in it that do not explicitly specify a theme. If the application theme is not explicitly set, the null is returned.

Returns:

the name of the application's theme.

setTheme

public void setTheme(String theme)

Sets the application's theme.

Note that this theme can be overridden in the the application level windows with Window.setTheme(String). Setting theme to be null selects the default theme. For the available theme names, see the contents of the VAADIN/themes directory.

Parameters:

theme - the new theme for this application.

getMainWindow

public Window getMainWindow()

Gets the mainWindow of the application.

The main window is the window attached to the application URL ( getURL()) and thus which is show by default to the user.

Note that each application must have at least one main window.

Returns:

the main window.

setMainWindow

public void setMainWindow(Window mainWindow)

Sets the mainWindow. If the main window is not explicitly set, the main window defaults to first created window. Setting window as a main window of this application also adds the window to this application.

Parameters:

mainWindow - the mainWindow to set.

getPropertyNames

public Enumeration<?> getPropertyNames()

Returns an enumeration of all the names in this application.

See start(URL, Properties, ApplicationContext) how properties are defined.

Returns:

an enumeration of all the keys in this property list, including the keys in the default property list.

getProperty

public String getProperty(String name)

Searches for the property with the specified name in this application. This method returns null if the property is not found. See start(URL, Properties, ApplicationContext) how properties are defined.

Parameters:

name - the name of the property.

Returns:

the value in this property list with the specified key value.

addResource

public void addResource(ApplicationResource resource)

Adds new resource to the application. The resource can be accessed by the user of the application.

Parameters:

resource - the resource to add.

removeResource

public void removeResource(ApplicationResource resource)

Removes the resource from the application.

Parameters:

resource - the resource to remove.

getRelativeLocation

@Deprecated
public String getRelativeLocation(ApplicationResource resource)

Deprecated. this method is intended to be used by the terminal only. It may be removed or moved in the future.

Gets the relative uri of the resource. This method is intended to be called only be the terminal implementation. This method can only be called from within the processing of a UIDL request, not from a background thread.

Parameters:

resource - the resource to get relative location.

Returns:

the relative uri of the resource or null if called in a background thread

handleURI

@Deprecated
public DownloadStream handleURI(URL context,
                                           String relativeUri)

Deprecated. this method is called be the terminal implementation only and might be removed or moved in the future. Instead of overriding this method, add your URIHandler to a top level Window (eg. getMainWindow().addUriHanler(handler) instead.

Application URI handling hub.

This method gets called by terminal. It has lots of duties like to pass uri handler to proper uri handlers registered to windows etc.

In most situations developers should NOT OVERRIDE this method. Instead developers should implement and register uri handlers to windows.

Specified by:

handleURI in interface URIHandler

Parameters:

context - the base URL

relativeUri - a URI relative to context

Returns:

A downloadable stream or null if no stream is provided

getLocale

public Locale getLocale()

Gets the default locale for this application. By default this is the preferred locale of the user using the application. In most cases it is read from the browser defaults.

Returns:

the locale of this application.

setLocale

public void setLocale(Locale locale)

Sets the default locale for this application. By default this is the preferred locale of the user using the application. In most cases it is read from the browser defaults.

Parameters:

locale - the Locale object.

addListener

public void addListener(Application.UserChangeListener listener)

Adds the user change listener. This allows one to get notification each time setUser(Object) is called.

Parameters:

listener - the user change listener to add.

removeListener

public void removeListener(Application.UserChangeListener listener)

Removes the user change listener.

Parameters:

listener - the user change listener to remove.

addListener

public void addListener(Application.WindowAttachListener listener)

Adds the window attach listener. Use this to get notifications each time a window is attached to the application with addWindow(Window).

Parameters:

listener - the window attach listener to add.

addListener

public void addListener(Application.WindowDetachListener listener)

Adds the window detach listener. Use this to get notifications each time a window is remove from the application with removeWindow(Window).

Parameters:

listener - the window detach listener to add.

removeListener

public void removeListener(Application.WindowAttachListener listener)

Removes the window attach listener.

Parameters:

listener - the window attach listener to remove.

removeListener

public void removeListener(Application.WindowDetachListener listener)

Removes the window detach listener.

Parameters:

listener - the window detach listener to remove.

getLogoutURL

public String getLogoutURL()

Returns the URL user is redirected to on application close. If the URL is null, the application is closed normally as defined by the application running environment.

Desktop application just closes the application window and web-application redirects the browser to application main URL.

Returns:

the URL.

setLogoutURL

public void setLogoutURL(String logoutURL)

Sets the URL user is redirected to on application close. If the URL is null, the application is closed normally as defined by the application running environment: Desktop application just closes the application window and web-application redirects the browser to application main URL.

Parameters:

logoutURL - the logoutURL to set.

getSystemMessages

public static Application.SystemMessages getSystemMessages()

Gets the SystemMessages for this application. SystemMessages are used to notify the user of various critical situations that can occur, such as session expiration, client/server out of sync, and internal server error. You can customize the messages by "overriding" this method and returning Application.CustomizedSystemMessages. To "override" this method, re-implement this method in your application (the class that extends Application). Even though overriding static methods is not possible in Java, Vaadin selects to call the static method from the subclass instead of the original getSystemMessages() if such a method exists.

Returns:

the SystemMessages for this application

terminalError

public void terminalError(Terminal.ErrorEvent event)

Invoked by the terminal on any exception that occurs in application and is thrown by the setVariable to the terminal. The default implementation sets the exceptions as ComponentErrors to the component that initiated the exception and prints stack trace to standard error stream.

You can safely override this method in your application in order to direct the errors to some other destination (for example log).

Specified by:

terminalError in interface Terminal.ErrorListener

Parameters:

event - the change event.

See Also:

Terminal.ErrorListener.terminalError(com.vaadin.terminal.Terminal.ErrorEvent)

getContext

public ApplicationContext getContext()

Gets the application context.

The application context is the environment where the application is running in. The actual implementation class of may contains quite a lot more functionality than defined in the ApplicationContext interface.

By default, when you are deploying your application to a servlet container, the implementation class is WebApplicationContext - you can safely cast to this class and use the methods from there. When you are deploying your application as a portlet, context implementation is PortletApplicationContext.

Returns:

the application context.

getVersion

public String getVersion()

Override this method to return correct version number of your Application. Version information is delivered for example to Testing Tools test results. By default this returns a string "NONVERSIONED".

Returns:

version string

getErrorHandler

public Terminal.ErrorListener getErrorHandler()

Gets the application error handler. The default error handler is the application itself.

Returns:

Application error handler

setErrorHandler

public void setErrorHandler(Terminal.ErrorListener errorHandler)

Sets the application error handler. The default error handler is the application itself. By overriding this, you can redirect the error messages to your selected target (log for example).

Parameters:

errorHandler -