Package com.vaadin.navigator

Class Navigator

  • All Implemented Interfaces:
    Serializable
    public class Navigator
extends Object
implements 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 uses a ViewDisplay to update contents based on the state.

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

    • 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 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 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 or null to use the default implementation
        display - The ViewDisplay used to display the views handled by this navigator

    • Method Detail

      • init

        protected void init​(UI ui,
                    NavigationStateManager stateManager,
                    ViewDisplay display)
        Initializes a navigator created with the no arguments constructor.

        When a custom navigation state manager is not needed, use null to create a default one based on URI fragments.

        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 or null for default
        display - The ViewDisplay used to display the views handled by this navigator
        Since:
        7.6

      • navigateTo

        public void navigateTo​(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:
        IllegalArgumentException - if navigationState does not map to a known view and no error view is registered

      • navigateTo

        protected void navigateTo​(View view,
                          String viewName,
                          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

      • revertNavigation

        protected void revertNavigation()
        Revert the changes to the navigation state. When navigation fails, this method can be called by navigateTo(View, String, String) to revert the URL fragment to point to the previous view to which navigation succeeded. This method should only be called by navigateTo(View, String, String). Normally it should not be overridden, but can be by frameworks that need to hook into view change cancellations of this type.
        Since:
        7.6

      • updateNavigationState

        protected void updateNavigationState​(ViewChangeListener.ViewChangeEvent event)
        Update the internal state of the navigator (parameters, previous successful URL fragment navigated to) when navigation succeeds. Normally this method should not be overridden nor called directly from application code, but it can be called by a custom implementation of navigateTo(View, String, String).
        Parameters:
        event - a view change event with details of the change
        Since:
        7.6

      • switchView

        protected void switchView​(ViewChangeListener.ViewChangeEvent event)
        Update the internal state of the navigator to reflect the actual switching of views. This method should only be called by navigateTo(View, String, String) between showing the view and calling View.enter(ViewChangeEvent). If this method is overridden, the overriding version must call the super method.
        Parameters:
        event - a view change event with details of the change
        Since:
        7.6

      • 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 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.
        Returns:
        the ViewDisplay used for displaying views

      • getUI

        public UI getUI()

      • getCurrentView

        public View getCurrentView()
        Return the currently active view.
        Returns:
        current view
        Since:
        7.6

      • 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​(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 - View instance (not null)

      • addView

        public void addView​(String viewName,
                    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 - View class to instantiate when a view is requested (not null)

      • 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, not null
        Throws:
        IllegalArgumentException - if the provided view provider is null

      • removeProvider

        public void removeProvider​(ViewProvider provider)
        Unregister a view provider (factory).
        Parameters:
        provider - provider to unregister

      • setErrorView

        public void setErrorView​(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.

      • destroy

        public void destroy()
        Creates view change event for given view, viewName and parameters.
        Since:
        7.6.7