    001// Copyright 2007-2013 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
    015package org.apache.tapestry5.corelib.components;
    016
    017import org.apache.tapestry5.BindingConstants;
    018import org.apache.tapestry5.Link;
    019import org.apache.tapestry5.MarkupWriter;
    020import org.apache.tapestry5.annotations.Parameter;
    021import org.apache.tapestry5.corelib.base.AbstractLink;
    022import org.apache.tapestry5.internal.InternalConstants;
    023import org.apache.tapestry5.ioc.annotations.Inject;
    024import org.apache.tapestry5.services.PageRenderLinkSource;
    025
    026/**
    027 * Generates a render request link to some other page in the application. If an activation context is supplied (as the
    028 * context parameter), then the context values will be encoded into the URL. If no context is supplied, then the target
    029 * page itself will supply the context via a passivate event.
    030 * <p/>
    031 * Pages are not required to have an activation context. When a page does have an activation context, the value
    032 * typically represents the identity of some object displayed or otherwise manipulated by the page.
    033 *
    034 * @tapestrydoc
    035 */
    036public class PageLink extends AbstractLink
    037{
    038    /**
    039     * The page to link to. If a <code>String</code>, as usual, it should be the page logical name.
    040     * If it's a <code>Class</code> instance, it's treated as the target page.
    041     * If it's not a <code>String</code> nor an <code>Class</code>, the target page will be
    042     * the result of calling <code>page.getClass()</code>.
    043     * Notice you'll need to use the <code>prop</code> binding when passing a value which
    044     * isn't a <code>String</code>.
    045     */
    046    @Parameter(required = true, allowNull = false, defaultPrefix = BindingConstants.LITERAL)
    047    private Object page;
    048
    049    /**
    050     * If provided, this is the activation context for the target page (the information will be encoded into the URL).
    051     * If not provided, then the target page will provide its own activation context.
    052     */
    053    @Parameter
    054    private Object[] context;
    055
    056    @Inject
    057    private PageRenderLinkSource linkSource;
    058
    059    void beginRender(MarkupWriter writer)
    060    {
    061        if (isDisabled()) return;
    062
    063        Link link;
    064        if (page instanceof String) {
    065            final String pageName = (String) page;
    066            link = resources.isBound("context")
    067                ? linkSource.createPageRenderLinkWithContext(pageName, context == null ? InternalConstants.EMPTY_STRING_ARRAY : context)
    068                : linkSource.createPageRenderLink(pageName);
    069        }
    070        else {
    071            // If page is a Class, use it directly. If not, use its class (type)
    072            Class<?> clasz = page instanceof Class<?> ? (Class<?>) page : page.getClass();
    073            link = resources.isBound("context")
    074                    ? linkSource.createPageRenderLinkWithContext(clasz, context == null ? InternalConstants.EMPTY_STRING_ARRAY : context)
    075                    : linkSource.createPageRenderLink(clasz);
    076        }
    077
    078        writeLink(writer, link);
    079    }
    080
    081    void afterRender(MarkupWriter writer)
    082    {
    083        if (isDisabled()) return;
    084
    085        writer.end(); // <a>
    086    }
    087}