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.markup.html.form; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.List; import java.util.Map; import java.util.StringTokenizer; import org.apache.wicket.MetaDataKey; import org.apache.wicket.markup.ComponentTag; import org.apache.wicket.model.IModel; import org.apache.wicket.util.convert.ConversionException; import org.apache.wicket.util.string.AppendingStringBuffer; import org.apache.wicket.util.string.Strings; /** * A multiple choice list component. * * @author Jonathan Locke * @author Johan Compagner * @author Martijn Dashorst * * @param <T> * The model object type */ public class ListMultipleChoice<T> extends AbstractChoice<Collection<T>, T> { private static final long serialVersionUID = 1L; /** Meta key for the retain disabled flag */ static MetaDataKey<Boolean> RETAIN_DISABLED_META_KEY = new MetaDataKey<Boolean>() { private static final long serialVersionUID = 1L; }; /** The default maximum number of rows to display. */ private static final int DEFAULT_MAX_ROWS = 8; /** The maximum number of rows to display. */ private int maxRows = DEFAULT_MAX_ROWS; /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String) */ public ListMultipleChoice(final String id) { super(id); } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, List) */ public ListMultipleChoice(final String id, final List<? extends T> choices) { super(id, choices); } /** * Creates a multiple choice list with a maximum number of visible rows. * * @param id * component id * @param choices * list of choices * @param maxRows * the maximum number of visible rows. * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, List) */ public ListMultipleChoice(final String id, final List<? extends T> choices, final int maxRows) { super(id, choices); this.maxRows = maxRows; } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, * List,IChoiceRenderer) */ public ListMultipleChoice(final String id, final List<? extends T> choices, final IChoiceRenderer<? super T> renderer) { super(id, choices, renderer); } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, IModel, List) * * @param id * @param object * @param choices */ @SuppressWarnings("unchecked") public ListMultipleChoice(final String id, IModel<? extends Collection<T>> object, final List<? extends T> choices) { super(id, (IModel<Collection<T>>) object, choices); } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, IModel, * List,IChoiceRenderer) * * @param id * @param object * @param choices * @param renderer */ @SuppressWarnings("unchecked") public ListMultipleChoice(final String id, IModel<? extends Collection<T>> object, final List<? extends T> choices, final IChoiceRenderer<? super T> renderer) { super(id, (IModel<Collection<T>>) object, choices, renderer); } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, IModel) */ public ListMultipleChoice(String id, IModel<? extends List<? extends T>> choices) { super(id, choices); } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, IModel,IModel) * * @param id * @param model * @param choices */ @SuppressWarnings("unchecked") public ListMultipleChoice(String id, IModel<? extends Collection<T>> model, IModel<? extends List<? extends T>> choices) { super(id, (IModel<Collection<T>>) model, choices); } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, * IModel,IChoiceRenderer) */ public ListMultipleChoice(String id, IModel<? extends List<? extends T>> choices, IChoiceRenderer<? super T> renderer) { super(id, choices, renderer); } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#AbstractChoice(String, IModel, * IModel,IChoiceRenderer) * * @param id * @param model * @param choices * @param renderer */ @SuppressWarnings("unchecked") public ListMultipleChoice(String id, IModel<? extends Collection<T>> model, IModel<? extends List<? extends T>> choices, IChoiceRenderer<? super T> renderer) { super(id, (IModel<Collection<T>>) model, choices, renderer); } /** * Sets the number of visible rows in the listbox. * * @param maxRows * the number of visible rows * @return this */ public final ListMultipleChoice<T> setMaxRows(final int maxRows) { this.maxRows = maxRows; return this; } /** * @see FormComponent#getModelValue() */ @Override public final String getModelValue() { final AppendingStringBuffer buffer = new AppendingStringBuffer(); final Collection<T> selectedValues = getModelObject(); if (selectedValues != null) { final List<? extends T> choices = getChoices(); for (T object : selectedValues) { if (buffer.length() > 0) { buffer.append(VALUE_SEPARATOR); } int index = choices.indexOf(object); buffer.append(getChoiceRenderer().getIdValue(object, index)); } } return buffer.toString(); } /** * @see org.apache.wicket.markup.html.form.AbstractChoice#isSelected(Object,int, String) */ @Override protected final boolean isSelected(T choice, int index, String selected) { // Have a value at all? if (selected != null) { String idValue = getChoiceRenderer().getIdValue(choice, index); // Loop through ids for (final StringTokenizer tokenizer = new StringTokenizer(selected, VALUE_SEPARATOR); tokenizer .hasMoreTokens();) { final String id = tokenizer.nextToken(); if (id.equals(idValue)) { return true; } } } return false; } /** * @see org.apache.wicket.Component#onComponentTag(ComponentTag) */ @Override protected void onComponentTag(final ComponentTag tag) { super.onComponentTag(tag); tag.put("multiple", "multiple"); if (!tag.getAttributes().containsKey("size")) { tag.put("size", Math.min(maxRows, getChoices().size())); } } /** * @see org.apache.wicket.markup.html.form.FormComponent#convertValue(String[]) */ @Override protected Collection<T> convertValue(String[] ids) throws ConversionException { if (ids != null && ids.length > 0 && !Strings.isEmpty(ids[0])) { return convertChoiceIdsToChoices(ids); } else { ArrayList<T> result = new ArrayList<>(); addRetainedDisabled(result); return result; } } /** * Converts submitted choice ids to choice objects. * * @param ids * choice ids. this array is nonnull and always contains at least one id. * @return list of choices. */ protected List<T> convertChoiceIdsToChoices(String[] ids) { ArrayList<T> selectedValues = new ArrayList<>(); // If one or more ids is selected if (ids != null && ids.length > 0 && !Strings.isEmpty(ids[0])) { // Get values that could be selected final Map<String, T> choiceIds2choiceValues = createChoicesIdsMap(); // Loop through selected indices for (String id : ids) { if (choiceIds2choiceValues.containsKey(id)) { selectedValues.add(choiceIds2choiceValues.get(id)); } } } addRetainedDisabled(selectedValues); return selectedValues; } /** * Creates a map of choice IDs to choice values. This map can be used to speed up lookups e.g. * in {@link #convertChoiceIdsToChoices(String[])}. <strong>Do not store the result of this * method.</strong> The choices list can change between requests so this map <em>must</em> be * regenerated. * * @return a map. */ private Map<String, T> createChoicesIdsMap() { final List<? extends T> choices = getChoices(); final Map<String, T> choiceIds2choiceValues = new HashMap<String, T>(choices.size(), 1); for (int index = 0; index < choices.size(); index++) { // Get next choice final T choice = choices.get(index); choiceIds2choiceValues.put(getChoiceRenderer().getIdValue(choice, index), choice); } return choiceIds2choiceValues; } private void addRetainedDisabled(ArrayList<T> selectedValues) { if (isRetainDisabledSelected()) { Collection<T> unchangedModel = getModelObject(); String selected; { StringBuilder builder = new StringBuilder(); for (T t : unchangedModel) { builder.append(t); builder.append(';'); } selected = builder.toString(); } List<? extends T> choices = getChoices(); for (int i = 0; i < choices.size(); i++) { final T choice = choices.get(i); if (isDisabled(choice, i, selected)) { if (unchangedModel.contains(choice)) { if (!selectedValues.contains(choice)) { selectedValues.add(choice); } } } } } } /** * See {@link FormComponent#updateCollectionModel(FormComponent)} for details on how the model * is updated. */ @Override public void updateModel() { FormComponent.updateCollectionModel(this); } /** * If true, choices that were selected in the model but disabled in rendering will be retained * in the model after a form submit. Example: Choices are [1, 2, 3, 4]. Model collection is [2, * 4]. In rendering, choices 2 and 3 are disabled ({@link #isDisabled(Object, int, String)}). * That means that four checkboxes are rendered, checkboxes 2 and 4 are checked, but 2 and 3 are * not clickable. User checks 1 and unchecks 4. If this flag is off, the model will be updated * to [1]. This is because the browser does not re-submit a disabled checked checkbox: it only * submits [1]. Therefore Wicket will only see the [1] and update the model accordingly. If you * set this flag to true, Wicket will check the model before updating to find choices that were * selected but disabled. These choices will then be retained, leading to a new model value of * [1, 2] as (probably) expected by the user. Note that this will lead to additional calls to * {@link #isDisabled(Object, int, String)}. * * @return flag */ public boolean isRetainDisabledSelected() { Boolean flag = getMetaData(RETAIN_DISABLED_META_KEY); return (flag != null && flag); } /** * @param retain * flag * @return this * @see #isRetainDisabledSelected() */ public ListMultipleChoice<T> setRetainDisabledSelected(boolean retain) { setMetaData(RETAIN_DISABLED_META_KEY, (retain) ? true : null); return this; } }