001    // Copyright 2007, 2008 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.corelib.components;
016    
017    import org.apache.tapestry5.BindingConstants;
018    import org.apache.tapestry5.ComponentResources;
019    import org.apache.tapestry5.Link;
020    import org.apache.tapestry5.MarkupWriter;
021    import org.apache.tapestry5.annotations.Parameter;
022    import org.apache.tapestry5.corelib.base.AbstractLink;
023    import org.apache.tapestry5.ioc.annotations.Inject;
024    
025    /**
026     * Generates a render request link to some other page in the application. If an activation context is supplied (as the
027     * context parameter), then the context values will be encoded into the URL. If no context is supplied, then the target
028     * page itself will supply the context via a passivate event.
029     * <p/>
030     * Pages are not required to have an activation context. When a page does have an activation context, the value
031     * typically represents the identity of some object displayed or otherwise manipulated by the page.
032     */
033    public class PageLink extends AbstractLink
034    {
035        /**
036         * The logical name of the page to link to.
037         */
038        @Parameter(required = true, allowNull = false, defaultPrefix = BindingConstants.LITERAL)
039        private String page;
040    
041        @Inject
042        private ComponentResources resources;
043    
044        /**
045         * If provided, this is the activation context for the target page (the information will be encoded into the URL).
046         * If not provided, then the target page will provide its own activation context.
047         */
048        @Parameter
049        private Object[] context;
050    
051        void beginRender(MarkupWriter writer)
052        {
053            if (isDisabled()) return;
054    
055            Link link = resources.createPageLink(page, resources.isBound("context"), context);
056    
057            writeLink(writer, link);
058        }
059    
060        void afterRender(MarkupWriter writer)
061        {
062            if (isDisabled()) return;
063    
064            writer.end(); // <a>
065        }
066    }