Module org.apache.wicket.extensions

Package org.apache.wicket.extensions.breadcrumb

Interface IBreadCrumbModel

All Superinterfaces:

IClusterable, Serializable

All Known Implementing Classes:

BreadCrumbBar, DefaultBreadCrumbsModel

public interface IBreadCrumbModel
extends IClusterable

Bread crumbs provide a means to track certain history of client actions. Bread crumbs are typically rendered as a list of links, and are useful when users 'dig deeper' into the site structure so that they can find their way back again and have a notion of where they currently are.

Bread crumbs in the original sense just represent where people are in a site hierarchy. For example, when browsing a product site, bread crumbs could look like this:

          Home > Products & Solutions > Hardware > Desktop Systems
 

or

          World > Europe > The Netherlands > Utrecht
 

These items would be rendered as links to the corresponding site location.

Classes that implement this interface are responsible for managing such a bread crumb structure. A typical implementation regards bread crumbs as a stack. When a bread crumb is activated that was not in the stack yet, it would add it to the stack, or when a bread crumb is activated that is already on the stack, it would roll back to the corresponding depth.

This model does not make any presumptions on how it should interact with components. Just that there is a list of bread crumb participants, and the notion of a currently active bread crumb participant.

A bread crumb participant is not an actual bread crumb, but rather a proxy to components that represent a certain location relative to other bread crumbs in this model, and a means to get the bread crumb title, which is typically rendered as a link label of the actual bread crumb. The actual bread crumbs are supposed to be rendered by a component that works together with this model. I choose this model as this would suit what I think is one of the nicest patterns: bread crumb aware panels.

Author:

Eelco Hillenius

Method Summary

Modifier and Type	Method	Description
void	addListener(IBreadCrumbModelListener listener)	Adds a bread crumb model listener.
List<IBreadCrumbParticipant>	allBreadCrumbParticipants()	Lists the bread crumb participants in this model.
IBreadCrumbParticipant	getActive()	Gets the currently active participant, if any.
void	removeListener(IBreadCrumbModelListener listener)	Removes a bread crumb model listener.
void	setActive(IBreadCrumbParticipant breadCrumbParticipant)	Sets the bread crumb as the active one.

Method Details

addListener

void addListener(IBreadCrumbModelListener listener)

Adds a bread crumb model listener.

Parameters:

listener - The listener to add

allBreadCrumbParticipants

List<IBreadCrumbParticipant> allBreadCrumbParticipants()

Lists the bread crumb participants in this model.

Returns:

The bread crumbs participants, as list with bread crumb participants.

getActive

IBreadCrumbParticipant getActive()

Gets the currently active participant, if any.

Returns:

The currently active participant, may be null

removeListener

void removeListener(IBreadCrumbModelListener listener)

Removes a bread crumb model listener.

Parameters:

listener - The listener to remove

setActive

void setActive(IBreadCrumbParticipant breadCrumbParticipant)

Sets the bread crumb as the active one. Implementations should call bread crumb added when the bread crumb was not yet part of the model, and bread crumb removed for every crumb that was removed as the result of this call.

Parameters:

breadCrumbParticipant - The bread crump that should be set as the currently active