org.apache.wicket.markup.html.basic.EnumLabel.java Source code

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Here is the source code for org.apache.wicket.markup.html.basic.EnumLabel.java

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/*
 * 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.basic;

import org.apache.wicket.IGenericComponent;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.MarkupStream;
import org.apache.wicket.markup.html.WebComponent;
import org.apache.wicket.markup.parser.XmlTag.TagType;
import org.apache.wicket.model.IModel;
import org.apache.wicket.model.Model;
import org.apache.wicket.util.lang.Classes;

/**
 * A Label component that is used to render an enum value. The value rendered will be the result
 * of a i18n resource lookup of the following form:
 * {@code <value.getClass().getSimpleName()>.<value.name()>}, this format can be changed by
 * overriding {@link #resourceKey(Enum)}
 * 
 * @author igor.vaynberg
 * @param <T>
 *            enum type
 */
public class EnumLabel<T extends Enum<T>> extends WebComponent implements IGenericComponent<T, EnumLabel<T>> {
    private static final long serialVersionUID = 1L;

    /**
     * Constructor
     * 
     * @param id
     *            See Component
     */
    public EnumLabel(final String id) {
        super(id);
    }

    /**
     * Convenience constructor. Same as Label(String, new Model&lt;String&gt;(String))
     * 
     * @param id
     *            See Component
     * @param value
     *            Enum value to render
     * 
     * @see org.apache.wicket.Component#Component(String, IModel)
     */
    public EnumLabel(final String id, T value) {
        this(id, new Model<T>(value));
    }

    /**
     * @param id
     * @param model
     * @see org.apache.wicket.Component#Component(String, IModel)
     */
    public EnumLabel(final String id, IModel<T> model) {
        super(id, model);
    }

    @Override
    public void onComponentTagBody(final MarkupStream markupStream, final ComponentTag openTag) {
        replaceComponentTagBody(markupStream, openTag, getStringValue());
    }

    /**
     * Converts model object into the display value
     * 
     * @return display value
     */
    private String getStringValue() {
        T value = getModelObject();
        String converted = value != null ? getString(resourceKey(value)) : nullValue();
        return getDefaultModelObjectAsString(converted);
    }

    /**
     * Converts enum value into a resource key that should be used to lookup the text the label will
     * display
     * 
     * @param value
     * @return resource key
     */
    protected String resourceKey(T value) {
        return Classes.simpleName(value.getDeclaringClass()) + '.' + value.name();
    }

    /**
     * @return value that should be displayed if model object is {@code null}
     */
    protected String nullValue() {
        return "";
    }

    @Override
    protected void onComponentTag(ComponentTag tag) {
        super.onComponentTag(tag);
        // always transform the tag to <span></span> so even labels defined as <span/> render
        tag.setType(TagType.OPEN);
    }
}