    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5;
    014
    015import org.apache.tapestry5.commons.util.CommonsUtils;
    016import org.apache.tapestry5.http.Link;
    017import org.apache.tapestry5.http.annotations.ImmutableSessionPersistedObject;
    018import org.apache.tapestry5.ioc.internal.util.InternalUtils;
    019import org.apache.tapestry5.services.PageRenderLinkSource;
    020
    021import java.io.Serializable;
    022
    023/**
    024 * A way of capturing the name of a page and the page activation context so that, at a future date,
    025 * the page can be invoked with that data. This kind of callback is very useful when creating more
    026 * complicated workflows, where access to a page is "interrupted" with some operation before
    027 * returning (via a callback) to the original flow.
    028 *
    029 * Since the callback is serializable, it can be stored in the session.
    030 *
    031 * @since 5.2.0
    032 */
    033@ImmutableSessionPersistedObject
    034public class PageCallback implements Serializable
    035{
    036    private static final long serialVersionUID = -8067619978636824702L;
    037
    038    private String pageName;
    039
    040    private String[] activationContext;
    041
    042    public PageCallback(String pageName, String[] activationContext)
    043    {
    044        assert InternalUtils.isNonBlank(pageName);
    045        this.pageName = pageName;
    046        assert activationContext != null;
    047        this.activationContext = activationContext;
    048    }
    049
    050    public PageCallback(String pageName, EventContext activationContext)
    051    {
    052        this(pageName, activationContext.toStrings());
    053    }
    054
    055    public PageCallback(String pageName)
    056    {
    057        this(pageName, CommonsUtils.EMPTY_STRING_ARRAY);
    058    }
    059
    060    public String getPageName()
    061    {
    062        return pageName;
    063    }
    064
    065    @Override
    066    public String toString()
    067    {
    068        if (hasActivationContext())
    069            return String.format("PageCallback[%s %s]", pageName, activationContextDescription());
    070
    071        return String.format("PageCallback[%s]", pageName);
    072    }
    073
    074    /** Does the activation context have any values? Used, typically, inside an override of {@link #toString()}. */
    075    protected final boolean hasActivationContext()
    076    {
    077        return activationContext.length > 0;
    078    }
    079
    080    /**
    081     * Returns the activation context as a string of value separated by slashes. Typically used inside
    082     * an override of {@link #toString()}.
    083     */
    084    protected final String activationContextDescription()
    085    {
    086        StringBuilder builder = new StringBuilder();
    087
    088        String sep = "";
    089
    090        for (String c : activationContext)
    091        {
    092            builder.append(sep);
    093            builder.append(c);
    094
    095            sep = "/";
    096        }
    097
    098        return builder.toString();
    099    }
    100
    101    /**
    102     * Converts the callback (the page name and activation context) to a link; such a link may be
    103     * returned from a event handler method to cause Tapestry to redirect to the page. Most of the
    104     * details
    105     * are encapsulated inside the {@link PageRenderLinkSource} service.
    106     *
    107     * @param linkSource
    108     *            used to generate the link
    109     * @return link corresponding to this callback
    110     */
    111    public Link toLink(PageRenderLinkSource linkSource)
    112    {
    113        return linkSource.createPageRenderLinkWithContext(pageName, (Object[]) activationContext);
    114    }
    115}