Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. * The ASF licenses this file to You under the Apache License, Version 2.0 * (the "License"); you may not use this file except in compliance with * the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.apache.wicket.extensions.markup.html.repeater.tree; import java.util.Set; import org.apache.wicket.Component; import org.apache.wicket.IGenericComponent; import org.apache.wicket.ajax.AjaxRequestTarget; import org.apache.wicket.core.request.handler.IPartialPageRequestHandler; import org.apache.wicket.extensions.markup.html.repeater.util.ProviderSubset; import org.apache.wicket.markup.html.panel.Panel; import org.apache.wicket.markup.repeater.DefaultItemReuseStrategy; import org.apache.wicket.markup.repeater.IItemReuseStrategy; import org.apache.wicket.markup.repeater.Item; import org.apache.wicket.model.IModel; /** * Abstract base class for {@link NestedTree} and {@link TableTree}. Uses its model for storing the * {@link State} of its nodes. * * Note that a tree has no notion of a <em>selection</em>. Handling state of nodes besides * expanse/collapse is irrelevant to a tree implementation. * * @see #newContentComponent(String, IModel) * * @author svenmeier * @param <T> * the node type */ public abstract class AbstractTree<T> extends Panel implements IGenericComponent<Set<T>, AbstractTree<T>> { private static final long serialVersionUID = 1L; private ITreeProvider<T> provider; private IItemReuseStrategy itemReuseStrategy; protected AbstractTree(String id, ITreeProvider<T> provider) { this(id, provider, null); } protected AbstractTree(String id, ITreeProvider<T> provider, IModel<? extends Set<T>> state) { super(id, state); if (provider == null) { throw new IllegalArgumentException("argument [provider] cannot be null"); } this.provider = provider; } /** * Sets the item reuse strategy. This strategy controls the creation of {@link Item}s. * * @see IItemReuseStrategy * * @param strategy * item reuse strategy * @return this for chaining */ public AbstractTree<T> setItemReuseStrategy(IItemReuseStrategy strategy) { this.itemReuseStrategy = strategy; return this; } /** * @return currently set item reuse strategy. Defaults to <code>DefaultItemReuseStrategy</code> * if none was set. * * @see DefaultItemReuseStrategy */ public IItemReuseStrategy getItemReuseStrategy() { if (itemReuseStrategy == null) { return DefaultItemReuseStrategy.getInstance(); } return itemReuseStrategy; } /** * Get the provider of the tree nodes. * * @return provider */ public ITreeProvider<T> getProvider() { return provider; } /** * Delegate to {@link #newModel()} if none is inited in super implementation. */ @Override protected IModel<?> initModel() { IModel<?> model = super.initModel(); if (model == null) { model = newModel(); } return model; } /** * Factory method for a model, by default creates a model containing a {@link ProviderSubset}. * Depending on your {@link ITreeProvider}'s model you might consider to provide a custom * {@link Set} implementation. * <p> * Note: The contained {@link Set} has at least to implement {@link Set#add(Object)}, * {@link Set#remove(Object)} and {@link Set#contains(Object)}. * * @return model for this tree */ protected IModel<Set<T>> newModel() { return new ProviderSubset<>(provider).createModel(); } /** * Expand the given node, tries to update the affected branch if the change happens on an * {@link AjaxRequestTarget}. * * @param t * the node to expand * * @see #getModelObject() * @see Set#add(Object) * @see #updateBranch(Object, IPartialPageRequestHandler) */ public void expand(T t) { modelChanging(); getModelObject().add(t); modelChanged(); getRequestCycle().find(IPartialPageRequestHandler.class).ifPresent(target -> updateBranch(t, target)); } /** * Collapse the given node, tries to update the affected branch if the change happens on an * {@link AjaxRequestTarget}. * * @param t * the object to collapse * * @see #getModelObject() * @see Set#remove(Object) * @see #updateBranch(Object, IPartialPageRequestHandler) */ public void collapse(T t) { modelChanging(); getModelObject().remove(t); modelChanged(); getRequestCycle().find(IPartialPageRequestHandler.class).ifPresent(target -> updateBranch(t, target)); } /** * Get the given node's {@link State}. * * @param t * the node to get state for * @return state * * @see #getModelObject() * @see Set#contains(Object) */ public State getState(T t) { if (getModelObject().contains(t)) { return State.EXPANDED; } else { return State.COLLAPSED; } } /** * Overridden to detach the {@link ITreeProvider}. */ @Override protected void onDetach() { provider.detach(); super.onDetach(); } /** * Create a new component for a node. * * @param id * the component id * @param model * the model containing the node * @return created component */ public Component newNodeComponent(String id, final IModel<T> model) { return new Node<T>(id, this, model) { private static final long serialVersionUID = 1L; @Override protected Component createContent(String id, IModel<T> model) { return AbstractTree.this.newContentComponent(id, model); } }; } /** * Create a new component for the content of a node. * * @param id * the component id * @param model * the model containing the node * @return created component */ protected abstract Component newContentComponent(String id, IModel<T> model); /** * Convenience method to update a single branch on an {@link AjaxRequestTarget}. Does nothing if * the given node is currently not visible. * * @param node * node to update * @param target * request target must not be @code null} */ public abstract void updateBranch(T node, IPartialPageRequestHandler target); /** * Convenience method to update a single node on an {@link AjaxRequestTarget}. Does nothing if * the given node is currently not visible. * * @param node * node to update * @param target * request target must not be @code null} */ public abstract void updateNode(T node, IPartialPageRequestHandler target); /** * The state of a node. */ public enum State { /** * The node is collapsed, i.e. its children are not iterated. */ COLLAPSED, /** * The node is expanded, i.e. its children are iterated. */ EXPANDED } }