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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.List;
    23
    24  import org.apache.turbine.Turbine;
    25  import org.apache.turbine.TurbineConstants;
    26  import org.apache.turbine.pipeline.PipelineData;
    27  import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService;
    28  import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker;
    29  import org.apache.turbine.util.RunData;
    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   * @version $Id: GenericLoader.java 1078552 2011-03-06 19:58:46Z tv $
    40   */
    41  public abstract class GenericLoader<T extends Assembler>
    42  {
    43      /** The Assembler Broker Service */
    44      protected AssemblerBrokerService ab = TurbineAssemblerBroker.getService();
    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      }
    62
    63      /**
    64       * Attempts to load and execute the external action that has been
    65       * set.
    66       * Should revert to abstract when RunData has gone.
    67       * @exception Exception a generic exception.
    68       */
    69      public void exec(PipelineData pipelineData, String name)
    70              throws Exception
    71      {
    72          RunData data = getRunData(pipelineData);
    73          exec(data, name);
    74      }
    75
    76
    77      /**
    78       * Attempts to load and execute the external action that has been
    79       * set.
    80       * @deprecated Use of this method should be avoided. Use
    81       * <code>exec(PipelineData data, String name)</code> instead.
    82       * @exception Exception a generic exception.
    83       */
    84      @Deprecated
    85      public abstract void exec(RunData data, String name)
    86      	throws Exception;
    87
    88      /**
    89       * Commented out.
    90       * This method should return the complete classpath + name.
    91       *
    92       * @param name
    93       * @return
    94       *
    95       public abstract String getClassName(String name);
    96       */
    97
    98      /**
    99       * Returns whether or not this external action is reload itself.
    100      * This is in cases where the Next button would be clicked, but
    101      * since we are checking for that, we would go into an endless
    102      * loop.
    103      *
    104      * @return True if the action is reload.
    105      */
    106     public boolean reload()
    107     {
    108         return this.reload;
    109     }
    110
    111     /**
    112      * Sets whether or not this external action is reload itself.
    113      * This is in cases where the Next button would be clicked, but
    114      * since we are checking for that, we would go into an endless
    115      * loop.
    116      *
    117      * @param reload True if the action must be marked as reload.
    118      * @return Itself.
    119      */
    120     public GenericLoader setReload(boolean reload)
    121     {
    122         this.reload = reload;
    123         return this;
    124     }
    125
    126     /**
    127      * Gets the base package where Turbine should find its default
    128      * modules.
    129      *
    130      * @return A String with the base package name.
    131      */
    132     public static String getBasePackage()
    133     {
    134         return TURBINE_PACKAGE;
    135     }
    136
    137     /**
    138      * Gets the package list where Turbine should find its
    139      * modules.
    140      *
    141      * @return A List with the package names (including the base package).
    142      */
    143     @SuppressWarnings("unchecked")
    144     public static List<String> getPackages()
    145     {
    146         if (TURBINE_PACKAGES == null)
    147         {
    148             TURBINE_PACKAGES =
    149                 Turbine.getConfiguration().getList(TurbineConstants.MODULE_PACKAGES);
    150         }
    151
    152         List<String> packages = TURBINE_PACKAGES;
    153
    154         if (!packages.contains(TURBINE_PACKAGE))
    155         {
    156             packages.add(TURBINE_PACKAGE);
    157         }
    158
    159         return packages;
    160     }
    161
    162     /**
    163      * Pulls out an instance of the object by name.  Name is just the
    164      * single name of the object.
    165      *
    166      * @param type Type of the assembler.
    167      * @param name Name of object instance.
    168      * @return A Screen with the specified name, or null.
    169      * @exception Exception a generic exception.
    170      */
    171     protected T getAssembler(String type, String name)
    172         throws Exception
    173     {
    174         T asm = null;
    175
    176         try
    177         {
    178             if (ab != null)
    179             {
    180                 // Attempt to load the assembler
    181                 asm = (T) ab.getAssembler(type, name);
    182             }
    183         }
    184         catch (ClassCastException cce)
    185         {
    186             // This can alternatively let this exception be thrown
    187             // So that the ClassCastException is shown in the
    188             // browser window.  Like this it shows "Screen not Found"
    189             asm = null;
    190         }
    191
    192         if (asm == null)
    193         {
    194             // If we did not find a screen we should try and give
    195             // the user a reason for that...
    196             // FIX ME: The AssemblerFactories should each add it's
    197             // own string here...
    198             List<String> packages = GenericLoader.getPackages();
    199
    200             throw new ClassNotFoundException(
    201                     "\n\n\tRequested " + type + " not found: " + name +
    202                     "\n\tTurbine looked in the following " +
    203                     "modules.packages path: \n\t" + packages.toString() + "\n");
    204         }
    205
    206         return asm;
    207     }
    208
    209     /**
    210      * Helper method to cast from PipelineData to RunData. This will go when
    211      * the pipeline is fully implemented and the RunData-methods are removed
    212      *
    213      * @param pipelineData a PipelineData object
    214      *
    215      * @return the input object casted to RunData
    216      */
    217     private RunData getRunData(PipelineData pipelineData)
    218     {
    219         if(!(pipelineData instanceof RunData))
    220         {
    221             throw new RuntimeException("Can't cast to rundata from pipeline data.");
    222         }
    223         return (RunData)pipelineData;
    224     }
    225 }