| package org.apache.turbine.modules; |
| |
| /* ==================================================================== |
| * The Apache Software License, Version 1.1 |
| * |
| * Copyright (c) 2001-2003 The Apache Software Foundation. All rights |
| * reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in |
| * the documentation and/or other materials provided with the |
| * distribution. |
| * |
| * 3. The end-user documentation included with the redistribution, |
| * if any, must include the following acknowledgment: |
| * "This product includes software developed by the |
| * Apache Software Foundation (http://www.apache.org/)." |
| * Alternately, this acknowledgment may appear in the software itself, |
| * if and wherever such third-party acknowledgments normally appear. |
| * |
| * 4. The names "Apache" and "Apache Software Foundation" and |
| * "Apache Turbine" must not be used to endorse or promote products |
| * derived from this software without prior written permission. For |
| * written permission, please contact apache@apache.org. |
| * |
| * 5. Products derived from this software may not be called "Apache", |
| * "Apache Turbine", nor may "Apache" appear in their name, without |
| * prior written permission of the Apache Software Foundation. |
| * |
| * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED |
| * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE |
| * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR |
| * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF |
| * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND |
| * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, |
| * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT |
| * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| * ==================================================================== |
| * |
| * This software consists of voluntary contributions made by many |
| * individuals on behalf of the Apache Software Foundation. For more |
| * information on the Apache Software Foundation, please see |
| * <http://www.apache.org/>. |
| */ |
| |
| import java.util.List; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| import org.apache.ecs.ConcreteElement; |
| import org.apache.turbine.Turbine; |
| import org.apache.turbine.TurbineConstants; |
| import org.apache.turbine.pipeline.PipelineData; |
| import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService; |
| import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker; |
| import org.apache.turbine.util.ObjectUtils; |
| import org.apache.turbine.util.RunData; |
| |
| /** |
| * The purpose of this class is to allow one to load and execute |
| * Navigation modules. |
| * |
| * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a> |
| * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> |
| * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> |
| * @version $Id$ |
| */ |
| public class NavigationLoader |
| extends GenericLoader |
| implements Loader |
| { |
| /** Logging */ |
| private static Log log = LogFactory.getLog(NavigationLoader.class); |
| |
| /** The single instance of this class. */ |
| private static NavigationLoader instance = |
| new NavigationLoader(Turbine.getConfiguration() |
| .getInt(TurbineConstants.NAVIGATION_CACHE_SIZE_KEY, |
| TurbineConstants.NAVIGATION_CACHE_SIZE_DEFAULT)); |
| |
| /** The Assembler Broker Service */ |
| private static AssemblerBrokerService ab = TurbineAssemblerBroker.getService(); |
| |
| /** |
| * These ctor's are private to force clients to use getInstance() |
| * to access this class. |
| */ |
| private NavigationLoader() |
| { |
| super(); |
| } |
| |
| /** |
| * These ctor's are private to force clients to use getInstance() |
| * to access this class. |
| */ |
| private NavigationLoader(int i) |
| { |
| super(i); |
| } |
| |
| /** |
| * Adds an instance of an object into the hashtable. |
| * |
| * @param name Name of object. |
| * @param navigation Navigation to be associated with name. |
| */ |
| private void addInstance(String name, Navigation navigation) |
| { |
| if (cache()) |
| { |
| this.put(name, navigation); |
| } |
| } |
| |
| /** |
| * Attempts to load and execute the external Navigation. This is |
| * used when you want to execute a Navigation which returns its |
| * output via a MultiPartElement instead of out the data.getPage() |
| * value. This allows you to easily chain the execution of |
| * Navigation modules together. |
| * |
| * @deprecated Use PipelineData version instead. |
| * @param data Turbine information. |
| * @param name Name of object that will execute the navigation. |
| * @exception Exception a generic exception. |
| */ |
| public ConcreteElement eval(RunData data, String name) |
| throws Exception |
| { |
| // Execute Navigation |
| return getInstance(name).build(data); |
| } |
| |
| /** |
| * Attempts to load and execute the external Navigation. This is |
| * used when you want to execute a Navigation which returns its |
| * output via a MultiPartElement instead of out the data.getPage() |
| * value. This allows you to easily chain the execution of |
| * Navigation modules together. |
| * |
| * @param data Turbine information. |
| * @param name Name of object that will execute the navigation. |
| * @exception Exception a generic exception. |
| */ |
| public ConcreteElement eval(PipelineData pipelineData, String name) |
| throws Exception |
| { |
| // Execute Navigation |
| return getInstance(name).build(pipelineData); |
| } |
| |
| |
| /** |
| * Attempts to load and execute the external Navigation. |
| * @deprecated Use PipelineData version instead. |
| * @param data Turbine information. |
| * @param name Name of object instance. |
| * @exception Exception a generic exception. |
| */ |
| public void exec(RunData data, String name) |
| throws Exception |
| { |
| this.eval(data, name); |
| } |
| |
| /** |
| * Attempts to load and execute the external Navigation. |
| * |
| * @param pipelineData Turbine information. |
| * @param name Name of object instance. |
| * @exception Exception a generic exception. |
| */ |
| public void exec(PipelineData pipelineData, String name) |
| throws Exception |
| { |
| this.eval(pipelineData, name); |
| } |
| |
| |
| /** |
| * Pulls out an instance of the object by name. Name is just the |
| * single name of the object. This is equal to getInstance but |
| * returns an Assembler object and is needed to fulfil the Loader |
| * interface. |
| * |
| * @param name Name of object instance. |
| * @return A Layout with the specified name, or null. |
| * @exception Exception a generic exception. |
| */ |
| public Assembler getAssembler(String name) |
| throws Exception |
| { |
| return getInstance(name); |
| } |
| |
| /** |
| * Pulls out an instance of the Navigation by name. Name is just the |
| * single name of the Navigation. |
| * |
| * @param name Name of requested Navigation |
| * @return A Navigation with the specified name, or null. |
| * @exception Exception a generic exception. |
| */ |
| public Navigation getInstance(String name) |
| throws Exception |
| { |
| Navigation navigation = null; |
| |
| // Check if the navigation is already in the cache |
| if (cache() && this.containsKey(name)) |
| { |
| navigation = (Navigation) this.get(name); |
| log.debug("Found Navigation " + name + " in the cache!"); |
| } |
| else |
| { |
| log.debug("Loading Navigation " + name + " from the Assembler Broker"); |
| |
| try |
| { |
| if (ab != null) |
| { |
| // Attempt to load the navigation |
| navigation = (Navigation) ab.getAssembler( |
| AssemblerBrokerService.NAVIGATION_TYPE, name); |
| } |
| } |
| catch (ClassCastException cce) |
| { |
| // This can alternatively let this exception be thrown |
| // So that the ClassCastException is shown in the |
| // browser window. Like this it shows "Screen not Found" |
| navigation = null; |
| } |
| |
| if (navigation == null) |
| { |
| // If we did not find a screen we should try and give |
| // the user a reason for that... |
| // FIX ME: The AssemblerFactories should each add it's |
| // own string here... |
| List packages = Turbine.getConfiguration() |
| .getList(TurbineConstants.MODULE_PACKAGES); |
| |
| ObjectUtils.addOnce(packages, |
| GenericLoader.getBasePackage()); |
| |
| throw new ClassNotFoundException( |
| "\n\n\tRequested Navigation not found: " + name + |
| "\n\tTurbine looked in the following " + |
| "modules.packages path: \n\t" + packages.toString() + "\n"); |
| } |
| else if (cache()) |
| { |
| // The new instance is added to the cache |
| addInstance(name, navigation); |
| } |
| } |
| return navigation; |
| } |
| |
| /** |
| * The method through which this class is accessed. |
| * |
| * @return The single instance of this class. |
| */ |
| public static NavigationLoader getInstance() |
| { |
| return instance; |
| } |
| } |