Java tutorial
/** * Copyright 2012 55 Minutes (http://www.55minutes.com) * * Licensed 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 fr.openwide.core.wicket.markup.html.model; import java.io.Serializable; import org.apache.wicket.Application; import org.apache.wicket.Component; import org.apache.wicket.model.AbstractReadOnlyModel; import org.apache.wicket.model.IComponentAssignedModel; import org.apache.wicket.model.IModel; import org.apache.wicket.model.IWrapModel; import org.apache.wicket.model.LoadableDetachableModel; import org.apache.wicket.model.Model; import org.apache.wicket.util.lang.Args; /** * Selects an appropriate localized string based on whether a count value is * zero, one or greater than one. This makes it easier to produce singluar and * plural phrases. * <p> * For example, consider the case where we would like to set one of these three * feedback messages. Notice how the phrasing is slightly different depending on * the number of items. Furthermore in the latter two examples we would like to * embed a hyperlink to a bookmarkable page. * <ul> * <li>There are no friends in your network.</li> * <li>There is <u>one friend</u> in your network.</li> * <li>There are <u>5 friends</u> in your network.</li> * </ul> * <p> * Normally in Wicket you would accomplish this using tedious if/else statements * and string concatenation, conditionally visible fragments/containers, or the * incredibly arcane syntax of Java's {@link java.text.ChoiceFormat * ChoiceFormat} (and note that you'd have to carefully escape the "<" and * ">" if you want to include HTML markup as we need for the hyperlinks in * this example). All of these approaches are clumsy, and it would be hard for a * non-programmer to localize or edit the strings. * <p> * You can now use this model in a label (also consider * {@link fiftyfive.wicket.basic.CountLabel CountLabel} as a shortcut for this * common use case), or call {@link #getObject getObject()} to get the * interpolated string value for use in a feedback message. * * @since 2.0 */ public class CountMessageModel extends AbstractReadOnlyModel<String> implements IComponentAssignedModel<String> { private static final long serialVersionUID = 3717960938783720989L; private String messageKey; private IModel<? extends Number> countModel; /** * Constructs a CountMessageModel that will choose the appropriate localized * string from a properties file. * * @param messageKey * The key that will be consulted in the properties file. The key * will have ".zero", ".one" or ".many" appended to it depending * on the value of the {@code count}. * @param component * The Wicket component that will be used for finding the * properties file. Usually this is the page or panel where you * plan to use the model. * @param count * The number that will be used in the message. This will be used * to substitute any <code>${count}</code> expressions in the * message. */ public CountMessageModel(String messageKey, IModel<? extends Number> count) { super(); Args.notNull(messageKey, "messageKey"); Args.notNull(count, "count"); this.messageKey = messageKey; this.countModel = count; } @Override public IWrapModel<String> wrapOnAssignment(Component component) { return new AssignmentWrapper(component); } @Override public void detach() { this.countModel.detach(); super.detach(); } @Override public String getObject() { // this shouldn't be called in the Wicket environment BUT we sometimes use this in Excel exports return Application.get().getResourceSettings().getLocalizer().getString(getResourceKey(), null, Model.of(getPropertySubstitutionBean())); } public int getCount() { Number num = this.countModel.getObject(); return num != null ? num.intValue() : 0; } public String getResourceKey() { StringBuilder sb = new StringBuilder(); sb.append(messageKey); sb.append(getResourceSuffix()); return sb.toString(); } /** * Returns either ".zero", ".one", or ".many" depending on the current value * of the count model. */ public String getResourceSuffix() { int count = getCount(); if (0 == count) { return ".zero"; } else if (1 == count) { return ".one"; } else { return ".many"; } } public PropertySubstitutionBean getPropertySubstitutionBean() { return new PropertySubstitutionBean(getCount()); } private static class PropertySubstitutionBean implements Serializable { private static final long serialVersionUID = 5422751133639920585L; private int count; private PropertySubstitutionBean(int count) { this.count = count; } @SuppressWarnings("unused") private int getCount() { return count; } } private class AssignmentWrapper extends LoadableDetachableModel<String> implements IWrapModel<String> { private static final long serialVersionUID = 1L; private final Component component; public AssignmentWrapper(Component component) { this.component = component; } /** * @see org.apache.wicket.model.IWrapModel#getWrappedModel() */ @Override public IModel<String> getWrappedModel() { return CountMessageModel.this; } @Override protected String load() { return Application.get().getResourceSettings().getLocalizer().getString( CountMessageModel.this.getResourceKey(), component, Model.of(CountMessageModel.this.getPropertySubstitutionBean())); } @Override protected void onDetach() { CountMessageModel.this.detach(); } } }