001    // Copyright 2004, 2005 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.tapestry.callback;
016    
017    import org.apache.hivemind.ApplicationRuntimeException;
018    import org.apache.hivemind.util.Defense;
019    import org.apache.tapestry.IExternalPage;
020    import org.apache.tapestry.IRequestCycle;
021    
022    /**
023     * A callback for returning to an {@link org.apache.tapestry.IExternalPage}.
024     * <p>
025     * Example usage of <tt>ExternalCallback</tt>:
026     * <p>
027     * The External page ensure a user is authenticated in the
028     * {@link org.apache.tapestry.IPage#validate(IRequestCycle)} method. If the user is not
029     * authenticated, they are redirected to the Login page, after setting a callback in the Login page.
030     * <p>
031     * The Login page <tt>formSubmit()</tt> {@link org.apache.tapestry.IActionListener} authenticates
032     * the user and then invokes {@link ICallback#performCallback(IRequestCycle)} to the External page.
033     * 
034     * <pre>
035     * 
036     *  
037     *   
038     *    
039     *     
040     *      
041     *       
042     *        
043     *         
044     *          
045     *           
046     *             public class External extends BasePage implements IExternalPage {
047     *            
048     *                 private Integer _itemId;
049     *           
050     *                 public void validate(IRequestCycle cycle) throws RequestCycleException {            
051     *                     Visit visit = (Visit) getVisit();
052     *                 
053     *                     if (!visit.isAuthenticated()) {
054     *                         Login login = (Login) cycle.getPage("Login");
055     *           
056     *                         login.setCallback
057     *                             (new ExternalCallback(this, cycle.getServiceParameters()));
058     *                         
059     *                         throw new PageRedirectException(login);
060     *                     }            
061     *                 }
062     *            
063     *                 public void activateExternalPage(Object[] params, IRequestCycle cycle)
064     *                         throws RequestCycleException {            
065     *                     _itemId = (Integer) params[0];
066     *                 }
067     *             }
068     *           
069     *             public Login extends BasePage {
070     *            
071     *                 private ICallback _callback;
072     *           
073     *                 public void setCallback(ICallback _callback) {
074     *                     _callback = callback;
075     *                 }
076     *           
077     *                 public void formSubmit(IRequestCycle cycle) {
078     *                     // Authentication code
079     *                     ..
080     *              
081     *                     Visit visit = (Visit) getVisit();
082     *           
083     *                     visit.setAuthenticated(true);
084     *             
085     *                     if (_callback != null) {
086     *                         _callback.performCallback(cycle);
087     *                     }
088     *                 }
089     *             }    
090     *             
091     *           
092     *          
093     *         
094     *        
095     *       
096     *      
097     *     
098     *    
099     *   
100     *  
101     * </pre>
102     * 
103     * @see org.apache.tapestry.IExternalPage
104     * @see org.apache.tapestry.engine.ExternalService
105     * @author Malcolm Edgar
106     * @since 2.3
107     */
108    
109    public class ExternalCallback implements ICallback
110    {
111        private static final long serialVersionUID = -6783421589702643930L;
112    
113        private String _pageName;
114    
115        private Object[] _parameters;
116    
117        /**
118         * Creates a new ExternalCallback for the named <tt>IExternalPage</tt>. The parameters (which
119         * may be null) is retained, not copied.
120         */
121    
122        public ExternalCallback(String pageName, Object[] parameters)
123        {
124            Defense.notNull(pageName, "pageName");
125    
126            _pageName = pageName;
127            _parameters = parameters;
128        }
129    
130        /**
131         * Creates a new ExternalCallback for the page. The parameters (which may be null) is retained,
132         * not copied.
133         */
134    
135        public ExternalCallback(IExternalPage page, Object[] parameters)
136        {
137            Defense.notNull(page, "page");
138    
139            _pageName = page.getPageName();
140            _parameters = parameters;
141        }
142    
143        /**
144         * Invokes {@link IRequestCycle#setPage(String)} to select the previously identified
145         * <tt>IExternalPage</tt> as the response page and activates the page by invoking
146         * <tt>activateExternalPage()</tt> with the callback parameters and request cycle.
147         */
148    
149        public void performCallback(IRequestCycle cycle)
150        {
151            Defense.notNull(cycle, "cycle");
152    
153            try
154            {
155                IExternalPage page = (IExternalPage) cycle.getPage(_pageName);
156    
157                cycle.activate(page);
158    
159                page.activateExternalPage(_parameters, cycle);
160            }
161            catch (ClassCastException ex)
162            {
163                throw new ApplicationRuntimeException(CallbackMessages.pageNotExternal(_pageName), ex);
164            }
165        }
166    
167        public String toString()
168        {
169            StringBuffer buffer = new StringBuffer("ExternalCallback[");
170    
171            buffer.append(_pageName);
172    
173            if (_parameters != null)
174            {
175                for (int i = 0; i < _parameters.length; i++)
176                {
177                    if (i == 0)
178                        buffer.append('/');
179                    else
180                        buffer.append(", ");
181    
182                    buffer.append(_parameters[i]);
183                }
184            }
185    
186            buffer.append(']');
187    
188            return buffer.toString();
189        }
190    }