wicketmessageresolver.java

Wicket一个开发Java Web应用程序框架。它使得开发web应用程序变得容易而轻松。 Wicket利用一个POJO data beans组件使得它可以与任何持久层技术相结合。

/*
 * 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.resolver;

import org.apache.wicket.MarkupContainer;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.MarkupElement;
import org.apache.wicket.markup.MarkupException;
import org.apache.wicket.markup.MarkupStream;
import org.apache.wicket.markup.RawMarkup;
import org.apache.wicket.markup.WicketTag;
import org.apache.wicket.markup.html.WebComponent;
import org.apache.wicket.markup.parser.XmlTag;
import org.apache.wicket.markup.parser.filter.WicketTagIdentifier;
import org.apache.wicket.model.Model;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


/**
 * This is a tag resolver which handles <wicket:message key="myKey">Default
 * Text</wicket:message>. The resolver will replace the whole tag with the message found in
 * the properties file associated with the Page. If no message is found, the default body text will
 * remain.
 * 
 * @author Juergen Donnerstag
 */
public class WicketMessageResolver implements IComponentResolver
{
	private static final Logger log = LoggerFactory.getLogger(WicketMessageResolver.class);

	/**
	 * If the key can't be resolved and the default is null, an exception will be thrown. Instead,
	 * we default to a unique string and check against this later. Don't just use an empty string
	 * here, as people might want to override wicket:messages to empty strings.
	 */
	private static final String DEFAULT_VALUE = "DEFAULT_WICKET_MESSAGE_RESOLVER_VALUE";

	static
	{
		// register "wicket:message"
		WicketTagIdentifier.registerWellKnownTagName("message");
	}


	private static final long serialVersionUID = 1L;

	/**
	 * Try to resolve the tag, then create a component, add it to the container and render it.
	 * 
	 * @see org.apache.wicket.markup.resolver.IComponentResolver#resolve(MarkupContainer,
	 *      MarkupStream, ComponentTag)
	 * 
	 * @param container
	 *            The container parsing its markup
	 * @param markupStream
	 *            The current markupStream
	 * @param tag
	 *            The current component tag while parsing the markup
	 * @return true, if componentId was handle by the resolver. False, otherwise
	 */
	public boolean resolve(final MarkupContainer container, final MarkupStream markupStream,
			final ComponentTag tag)
	{
		if (tag instanceof WicketTag)
		{
			WicketTag wtag = (WicketTag)tag;
			if (wtag.isMessageTag())
			{
				String messageKey = wtag.getAttributes().getString("key");
				if ((messageKey == null) || (messageKey.trim().length() == 0))
				{
					throw new MarkupException(
							"Wrong format of <wicket:message key='xxx'>: attribute 'key' is missing");
				}

				final String id = "_message_" + container.getPage().getAutoIndex();
				MessageLabel label = new MessageLabel(id, messageKey);
				label.setRenderBodyOnly(container.getApplication().getMarkupSettings()
						.getStripWicketTags());
				container.autoAdd(label, markupStream);

				// Yes, we handled the tag
				return true;
			}
		}

		// We were not able to handle the tag
		return false;
	}

	/**
	 * A Label with expands open-close tags to open-body-close if required
	 */
	public static class MessageLabel extends WebComponent
	{
		private static final long serialVersionUID = 1L;

		/**
		 * Construct.
		 * 
		 * @param id
		 * @param messageKey
		 */
		public MessageLabel(final String id, final String messageKey)
		{
			super(id, new Model(messageKey));
			setEscapeModelStrings(false);
		}

		protected void onComponentTagBody(MarkupStream markupStream, ComponentTag openTag)
		{
			final String key = getModelObjectAsString();
			final String value = getLocalizer().getString(key, getParent(), DEFAULT_VALUE);
			if (value != null && !DEFAULT_VALUE.equals(value))
			{
				replaceComponentTagBody(markupStream, openTag, value.trim());
			}
			else
			{
				log.debug("No value found for wicket:message tag with key: {}", key);

				// get original tag from markup because we modified this one to always be open
				markupStream.setCurrentIndex(markupStream.getCurrentIndex() - 1);
				ComponentTag tag = markupStream.getTag();
				markupStream.next();

				// if the tag is of form <wicket:message>{foo}</wicket:message> use {foo} as
				// default value for the message, otherwise do nothing
				if (!tag.isOpenClose())
				{
					MarkupElement body = markupStream.get();
					if (body instanceof RawMarkup)
					{
						replaceComponentTagBody(markupStream, openTag, body.toCharSequence());
					}
				}
			}
		}

		/**
		 * 
		 * @see org.apache.wicket.Component#onComponentTag(org.apache.wicket.markup.ComponentTag)
		 */
		protected void onComponentTag(ComponentTag tag)
		{
			// Convert <wicket:message /> into <wicket:message>...</wicket:message>
			if (tag.isOpenClose())
			{
				tag.setType(XmlTag.OPEN);
			}
			super.onComponentTag(tag);
		}
	}
}