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    1   package org.apache.turbine.modules;
    2
    3   /*
    4    * Licensed to the Apache Software Foundation (ASF) under one
    5    * or more contributor license agreements.  See the NOTICE file
    6    * distributed with this work for additional information
    7    * regarding copyright ownership.  The ASF licenses this file
    8    * to you under the Apache License, Version 2.0 (the
    9    * "License"); you may not use this file except in compliance
    10   * with the License.  You may obtain a copy of the License at
    11   *
    12   *   http://www.apache.org/licenses/LICENSE-2.0
    13   *
    14   * Unless required by applicable law or agreed to in writing,
    15   * software distributed under the License is distributed on an
    16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    17   * KIND, either express or implied.  See the License for the
    18   * specific language governing permissions and limitations
    19   * under the License.
    20   */
    21
    22  import java.util.ArrayList;
    23  import java.util.List;
    24
    25  import org.apache.turbine.Turbine;
    26  import org.apache.turbine.TurbineConstants;
    27  import org.apache.turbine.pipeline.PipelineData;
    28  import org.apache.turbine.services.TurbineServices;
    29  import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService;
    30
    31  /**
    32   * This is the base class for the loaders. It contains code that is
    33   * used across all of the loaders. It also specifies the interface
    34   * that is required to be called a Loader.
    35   *
    36   * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
    37   * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
    38   * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a>
    39   * @param <T> the specialized assembler type
    40   */
    41  public abstract class GenericLoader<T extends Assembler>
    42  {
    43      /** The Assembler Broker Service */
    44      protected AssemblerBrokerService ab;
    45
    46      /** @serial This can be serialized */
    47      private boolean reload = false;
    48
    49      /** Base packages path for Turbine */
    50      private static final String TURBINE_PACKAGE = "org.apache.turbine.modules";
    51
    52      /** Packages paths for Turbine */
    53      private static List<String> TURBINE_PACKAGES = null;
    54
    55      /**
    56       * Basic constructor for creating a loader.
    57       */
    58      public GenericLoader()
    59      {
    60          super();
    61          ab = (AssemblerBrokerService)TurbineServices.getInstance().getService(AssemblerBrokerService.SERVICE_NAME);
    62      }
    63
    64      /**
    65       * Attempts to load and execute the external action that has been
    66       * set.
    67       * @param pipelineData the Turbine request
    68       * @param name the name of the assembler module
    69       * @throws Exception a generic exception.
    70       */
    71      public abstract void exec(PipelineData pipelineData, String name)
    72              throws Exception;
    73
    74      /**
    75       * Returns whether or not this external action is reload itself.
    76       * This is in cases where the Next button would be clicked, but
    77       * since we are checking for that, we would go into an endless
    78       * loop.
    79       *
    80       * @return True if the action is reload.
    81       */
    82      public boolean reload()
    83      {
    84          return this.reload;
    85      }
    86
    87      /**
    88       * Sets whether or not this external action is reload itself.
    89       * This is in cases where the Next button would be clicked, but
    90       * since we are checking for that, we would go into an endless
    91       * loop.
    92       *
    93       * @param reload True if the action must be marked as reload.
    94       * @return Itself.
    95       */
    96      public GenericLoader<T> setReload(boolean reload)
    97      {
    98          this.reload = reload;
    99          return this;
    100     }
    101
    102     /**
    103      * Gets the base package where Turbine should find its default
    104      * modules.
    105      *
    106      * @return A String with the base package name.
    107      */
    108     public static String getBasePackage()
    109     {
    110         return TURBINE_PACKAGE;
    111     }
    112
    113     /**
    114      * Gets the package list where Turbine should find its
    115      * modules.
    116      *
    117      * @return A List with the package names (including the base package).
    118      */
    119     public static List<String> getPackages()
    120     {
    121         if (TURBINE_PACKAGES == null)
    122         {
    123             List<String> turbinePackages = new ArrayList<String>();
    124             List<Object> configTurbinePackages =
    125                 Turbine.getConfiguration()
    126                 	.getList(TurbineConstants.MODULE_PACKAGES);
    127             for (Object o : configTurbinePackages)
    128             {
    129             	turbinePackages.add((String)o);
    130             }
    131
    132             TURBINE_PACKAGES = turbinePackages;
    133         }
    134
    135         List<String> packages = TURBINE_PACKAGES;
    136
    137         if (!packages.contains(TURBINE_PACKAGE))
    138         {
    139             packages.add(TURBINE_PACKAGE);
    140         }
    141
    142         return packages;
    143     }
    144
    145     /**
    146      * Pulls out an instance of the object by name.  Name is just the
    147      * single name of the object.
    148      *
    149      * @param type Type of the assembler.
    150      * @param name Name of object instance.
    151      * @return A Screen with the specified name, or null.
    152      * @throws Exception a generic exception.
    153      */
    154     protected T getAssembler(Class<T> type, String name)
    155         throws Exception
    156     {
    157         T asm = null;
    158
    159         try
    160         {
    161             if (ab != null)
    162             {
    163                 // Attempt to load the assembler
    164                 asm = ab.getAssembler(type, name);
    165             }
    166         }
    167         catch (ClassCastException cce)
    168         {
    169             // This can alternatively let this exception be thrown
    170             // So that the ClassCastException is shown in the
    171             // browser window.  Like this it shows "Screen not Found"
    172             asm = null;
    173         }
    174
    175         if (asm == null)
    176         {
    177             // If we did not find a screen we should try and give
    178             // the user a reason for that...
    179             // FIX ME: The AssemblerFactories should each add it's
    180             // own string here...
    181             List<String> packages = GenericLoader.getPackages();
    182
    183             throw new ClassNotFoundException(
    184                     "\n\n\tRequested " + type + " not found: " + name +
    185                     "\n\tTurbine looked in the following " +
    186                     "modules.packages path: \n\t" + packages.toString() + "\n");
    187         }
    188
    189         return asm;
    190     }
    191 }