    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
    015    package org.apache.tapestry5;
    016
    017    import java.io.Serializable;
    018
    019    import org.apache.tapestry5.annotations.ImmutableSessionPersistedObject;
    020    import org.apache.tapestry5.internal.InternalConstants;
    021    import org.apache.tapestry5.ioc.internal.util.InternalUtils;
    022    import 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
    035    public 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    }