com.vaadin.navigator
Class Navigator

java.lang.Object
  extended by com.vaadin.navigator.Navigator
All Implemented Interfaces:
java.io.Serializable

public class Navigator
extends java.lang.Object
implements java.io.Serializable

A navigator utility that allows switching of views in a part of an application.

The view switching can be based e.g. on URI fragments containing the view name and parameters to the view. There are two types of parameters for views: an optional parameter string that is included in the fragment (may be bookmarkable).

Views can be explicitly registered or dynamically generated and listening to view changes is possible.

Note that Navigator is not a component itself but comes with SimpleViewDisplay which is a component that displays the selected view as its contents.

Since:
7.0
Author:
Vaadin Ltd
See Also:
Serialized Form

Nested Class Summary
static class Navigator.ClassBasedViewProvider
          A ViewProvider which maps a single view name to a class to instantiate for the view.
static class Navigator.ComponentContainerViewDisplay
          A ViewDisplay that replaces the contents of a ComponentContainer with the active View.
static class Navigator.EmptyView
          Empty view component.
static class Navigator.SingleComponentContainerViewDisplay
          A ViewDisplay that replaces the contents of a SingleComponentContainer with the active View.
static class Navigator.StaticViewProvider
          A ViewProvider which supports mapping a single view name to a single pre-initialized view instance.
static class Navigator.UriFragmentManager
          A NavigationStateManager using hashbang fragments in the Page location URI to track views and enable listening to view changes.
 
Constructor Summary
Navigator(UI ui, ComponentContainer container)
          Creates a navigator that is tracking the active view using URI fragments of the Page containing the given UI and replacing the contents of a ComponentContainer with the active view.
Navigator(UI ui, NavigationStateManager stateManager, ViewDisplay display)
          Creates a navigator.
Navigator(UI ui, SingleComponentContainer container)
          Creates a navigator that is tracking the active view using URI fragments of the Page containing the given UI and replacing the contents of a SingleComponentContainer with the active view.
Navigator(UI ui, ViewDisplay display)
          Creates a navigator that is tracking the active view using URI fragments of the Page containing the given UI.
 
Method Summary
 void addProvider(ViewProvider provider)
          Registers a view provider (factory).
 void addView(java.lang.String viewName, java.lang.Class<? extends View> viewClass)
          Registers a view class for a view name.
 void addView(java.lang.String viewName, View view)
          Registers a static, pre-initialized view instance for a view name.
 void addViewChangeListener(ViewChangeListener listener)
          Listen to changes of the active view.
protected  void fireAfterViewChange(ViewChangeListener.ViewChangeEvent event)
          Fires an event after the current view has changed.
protected  boolean fireBeforeViewChange(ViewChangeListener.ViewChangeEvent event)
          Fires an event before an imminent view change.
 ViewDisplay getDisplay()
          Return the ViewDisplay used by the navigator.
 java.lang.String getState()
          Returns the current navigation state reported by this Navigator's NavigationStateManager.
protected  NavigationStateManager getStateManager()
          Returns the NavigationStateManager that is used to get, listen to and manipulate the navigation state used by this Navigator.
 UI getUI()
           
 void navigateTo(java.lang.String navigationState)
          Navigates to a view and initialize the view with given parameters.
protected  void navigateTo(View view, java.lang.String viewName, java.lang.String parameters)
          Internal method activating a view, setting its parameters and calling listeners.
 void removeProvider(ViewProvider provider)
          Unregister a view provider (factory).
 void removeView(java.lang.String viewName)
          Removes a view from navigator.
 void removeViewChangeListener(ViewChangeListener listener)
          Removes a view change listener.
 void setErrorProvider(ViewProvider provider)
          Registers a view provider that is queried for a view when no other view matches the navigation state.
 void setErrorView(java.lang.Class<? extends View> viewClass)
          Registers a view class that is instantiated when no other view matches the navigation state.
 void setErrorView(View view)
          Registers a view that is displayed when no other view matches the navigation state.
 
Methods inherited from class java.lang.Object
equals, finalize, getClass, hashCode, toString
 

Constructor Detail

Navigator

public Navigator(UI ui,
                 ComponentContainer container)
Creates a navigator that is tracking the active view using URI fragments of the Page containing the given UI and replacing the contents of a ComponentContainer with the active view.

All components of the container are removed each time before adding the active Navigator.EmptyView. Views must implement Component when using this constructor.

Navigation is automatically initiated after UI.init() if a navigator was created. If at a later point changes are made to the navigator, navigator.navigateTo(navigator.getState()) may need to be explicitly called to ensure the current view matches the navigation state.

Parameters:
ui - The UI to which this Navigator is attached.
container - The ComponentContainer whose contents should be replaced with the active view on view change

Navigator

public Navigator(UI ui,
                 SingleComponentContainer container)
Creates a navigator that is tracking the active view using URI fragments of the Page containing the given UI and replacing the contents of a SingleComponentContainer with the active view.

Views must implement Component when using this constructor.

Navigation is automatically initiated after UI.init() if a navigator was created. If at a later point changes are made to the navigator, navigator.navigateTo(navigator.getState()) may need to be explicitly called to ensure the current view matches the navigation state.

Parameters:
ui - The UI to which this Navigator is attached.
container - The SingleComponentContainer whose contents should be replaced with the active view on view change

Navigator

public Navigator(UI ui,
                 ViewDisplay display)
Creates a navigator that is tracking the active view using URI fragments of the Page containing the given UI.

Navigation is automatically initiated after UI.init() if a navigator was created. If at a later point changes are made to the navigator, navigator.navigateTo(navigator.getState()) may need to be explicitly called to ensure the current view matches the navigation state.

Parameters:
ui - The UI to which this Navigator is attached.
display - The ViewDisplay used to display the views.

Navigator

public Navigator(UI ui,
                 NavigationStateManager stateManager,
                 ViewDisplay display)
Creates a navigator.

When a custom navigation state manager is not needed, use one of the other constructors which use a URI fragment based state manager.

Navigation is automatically initiated after UI.init() if a navigator was created. If at a later point changes are made to the navigator, navigator.navigateTo(navigator.getState()) may need to be explicitly called to ensure the current view matches the navigation state.

Parameters:
ui - The UI to which this Navigator is attached.
stateManager - The NavigationStateManager keeping track of the active view and enabling bookmarking and direct navigation
display - The ViewDisplay used to display the views handled by this navigator
Method Detail

navigateTo

public void navigateTo(java.lang.String navigationState)
Navigates to a view and initialize the view with given parameters.

The view string consists of a view name optionally followed by a slash and a parameters part that is passed as-is to the view. ViewProviders are used to find and create the correct type of view.

If multiple providers return a matching view, the view with the longest name is selected. This way, e.g. hierarchies of subviews can be registered like "admin/", "admin/users", "admin/settings" and the longest match is used.

If the view being deactivated indicates it wants a confirmation for the navigation operation, the user is asked for the confirmation.

Registered ViewChangeListeners are called upon successful view change.

Parameters:
navigationState - view name and parameters
Throws:
java.lang.IllegalArgumentException - if navigationState does not map to a known view and no error view is registered

navigateTo

protected void navigateTo(View view,
                          java.lang.String viewName,
                          java.lang.String parameters)
Internal method activating a view, setting its parameters and calling listeners.

This method also verifies that the user is allowed to perform the navigation operation.

Parameters:
view - view to activate
viewName - (optional) name of the view or null not to change the navigation state
parameters - parameters passed in the navigation state to the view

fireBeforeViewChange

protected boolean fireBeforeViewChange(ViewChangeListener.ViewChangeEvent event)
Fires an event before an imminent view change.

Listeners are called in registration order. If any listener returns false, the rest of the listeners are not called and the view change is blocked.

The view change listeners may also e.g. open a warning or question dialog and save the parameters to re-initiate the navigation operation upon user action.

Parameters:
event - view change event (not null, view change not yet performed)
Returns:
true if the view change should be allowed, false to silently block the navigation operation

getStateManager

protected NavigationStateManager getStateManager()
Returns the NavigationStateManager that is used to get, listen to and manipulate the navigation state used by this Navigator.

Returns:
NavigationStateManager in use

getState

public java.lang.String getState()
Returns the current navigation state reported by this Navigator's NavigationStateManager.

Returns:
The navigation state.

getDisplay

public ViewDisplay getDisplay()
Return the ViewDisplay used by the navigator. Unless another display is specified, a SimpleViewDisplay (which is a Component) is used by default.

Returns:
current ViewDisplay

getUI

public UI getUI()

fireAfterViewChange

protected void fireAfterViewChange(ViewChangeListener.ViewChangeEvent event)
Fires an event after the current view has changed.

Listeners are called in registration order.

Parameters:
event - view change event (not null)

addView

public void addView(java.lang.String viewName,
                    View view)
Registers a static, pre-initialized view instance for a view name.

Registering another view with a name that is already registered overwrites the old registration of the same type.

Note that a view should not be shared between UIs (for instance, it should not be a static field in a UI subclass).

Parameters:
viewName - String that identifies a view (not null nor empty string)
view - Navigator.EmptyView instance (not null)

addView

public void addView(java.lang.String viewName,
                    java.lang.Class<? extends View> viewClass)
Registers a view class for a view name.

Registering another view with a name that is already registered overwrites the old registration of the same type.

A new view instance is created every time a view is requested.

Parameters:
viewName - String that identifies a view (not null nor empty string)
viewClass - Navigator.EmptyView class to instantiate when a view is requested (not null)

removeView

public void removeView(java.lang.String viewName)
Removes a view from navigator.

This method only applies to views registered using addView(String, View) or addView(String, Class).

Parameters:
viewName - name of the view to remove

addProvider

public void addProvider(ViewProvider provider)
Registers a view provider (factory).

Providers are called in order of registration until one that can handle the requested view name is found.

Parameters:
provider - provider to register

removeProvider

public void removeProvider(ViewProvider provider)
Unregister a view provider (factory).

Parameters:
provider - provider to unregister

setErrorView

public void setErrorView(java.lang.Class<? extends View> viewClass)
Registers a view class that is instantiated when no other view matches the navigation state. This implicitly sets an appropriate error view provider and overrides any previous setErrorProvider(ViewProvider) call.

Note that an error view should not be shared between UIs (for instance, it should not be a static field in a UI subclass).

Parameters:
viewClass - The View class whose instance should be used as the error view.

setErrorView

public void setErrorView(View view)
Registers a view that is displayed when no other view matches the navigation state. This implicitly sets an appropriate error view provider and overrides any previous setErrorProvider(ViewProvider) call.

Parameters:
view - The View that should be used as the error view.

setErrorProvider

public void setErrorProvider(ViewProvider provider)
Registers a view provider that is queried for a view when no other view matches the navigation state. An error view provider should match any navigation state, but could return different views for different states. Its getViewName(String navigationState) should return navigationState.

Parameters:
provider -

addViewChangeListener

public void addViewChangeListener(ViewChangeListener listener)
Listen to changes of the active view.

Registered listeners are invoked in registration order before ( beforeViewChange()) and after ( afterViewChange()) a view change occurs.

Parameters:
listener - Listener to invoke during a view change.

removeViewChangeListener

public void removeViewChangeListener(ViewChangeListener listener)
Removes a view change listener.

Parameters:
listener - Listener to remove.


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