    001// Copyright 2010 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;
    016
    017import java.io.Serializable;
    018
    019import org.apache.tapestry5.annotations.ImmutableSessionPersistedObject;
    020import org.apache.tapestry5.internal.InternalConstants;
    021import org.apache.tapestry5.ioc.internal.util.InternalUtils;
    022import org.apache.tapestry5.services.PageRenderLinkSource;
    023
    024/**
    025 * A way of capturing the name of a page and the page activation context so that, at a future date,
    026 * the page can be invoked with that data. This kind of callback is very useful when creating more
    027 * complicated workflows, where access to a page is "interrupted" with some operation before
    028 * returning (via a callback) to the original flow.
    029 * <p>
    030 * Since the callback is serializable, it can be stored in the session.
    031 *
    032 * @since 5.2.0
    033 */
    034@ImmutableSessionPersistedObject
    035public class PageCallback implements Serializable
    036{
    037    private static final long serialVersionUID = -8067619978636824702L;
    038
    039    private String pageName;
    040
    041    private String[] activationContext;
    042
    043    public PageCallback(String pageName, String[] activationContext)
    044    {
    045        assert InternalUtils.isNonBlank(pageName);
    046        this.pageName = pageName;
    047        assert activationContext != null;
    048        this.activationContext = activationContext;
    049    }
    050
    051    public PageCallback(String pageName, EventContext activationContext)
    052    {
    053        this(pageName, activationContext.toStrings());
    054    }
    055
    056    public PageCallback(String pageName)
    057    {
    058        this(pageName, InternalConstants.EMPTY_STRING_ARRAY);
    059    }
    060
    061    public String getPageName()
    062    {
    063        return pageName;
    064    }
    065
    066    @Override
    067    public String toString()
    068    {
    069        if (hasActivationContext())
    070            return String.format("PageCallback[%s %s]", pageName, activationContextDescription());
    071
    072        return String.format("PageCallback[%s]", pageName);
    073    }
    074
    075    /** Does the activation context have any values? Used, typically, inside an override of {@link #toString()}. */
    076    protected final boolean hasActivationContext()
    077    {
    078        return activationContext.length > 0;
    079    }
    080
    081    /**
    082     * Returns the activation context as a string of value separated by slashes. Typically used inside
    083     * an override of {@link #toString()}.
    084     */
    085    protected final String activationContextDescription()
    086    {
    087        StringBuilder builder = new StringBuilder();
    088
    089        String sep = "";
    090
    091        for (String c : activationContext)
    092        {
    093            builder.append(sep);
    094            builder.append(c);
    095
    096            sep = "/";
    097        }
    098
    099        return builder.toString();
    100    }
    101
    102    /**
    103     * Converts the callback (the page name and activation context) to a link; such a link may be
    104     * returned from a event handler method to cause Tapestry to redirect to the page. Most of the
    105     * details
    106     * are encapsulated inside the {@link PageRenderLinkSource} service.
    107     *
    108     * @param linkSource
    109     *            used to generate the link
    110     * @return link corresponding to this callback
    111     */
    112    public Link toLink(PageRenderLinkSource linkSource)
    113    {
    114        return linkSource.createPageRenderLinkWithContext(pageName, (Object[]) activationContext);
    115    }
    116}