Coverage report

  %line %branch
org.apache.turbine.modules.ScreenLoader
59% 
90% 

 1  
 package org.apache.turbine.modules;
 2  
 
 3  
 /*
 4  
  * Copyright 2001-2004 The Apache Software Foundation.
 5  
  *
 6  
  * Licensed under the Apache License, Version 2.0 (the "License")
 7  
  * you may not use this file except in compliance with the License.
 8  
  * You may obtain a copy of the License at
 9  
  *
 10  
  *     http://www.apache.org/licenses/LICENSE-2.0
 11  
  *
 12  
  * Unless required by applicable law or agreed to in writing, software
 13  
  * distributed under the License is distributed on an "AS IS" BASIS,
 14  
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 15  
  * See the License for the specific language governing permissions and
 16  
  * limitations under the License.
 17  
  */
 18  
 
 19  
 import java.util.List;
 20  
 
 21  
 import org.apache.commons.logging.Log;
 22  
 import org.apache.commons.logging.LogFactory;
 23  
 
 24  
 import org.apache.ecs.ConcreteElement;
 25  
 
 26  
 import org.apache.turbine.Turbine;
 27  
 import org.apache.turbine.TurbineConstants;
 28  
 import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService;
 29  
 import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker;
 30  
 import org.apache.turbine.util.ObjectUtils;
 31  
 import org.apache.turbine.util.RunData;
 32  
 
 33  
 /**
 34  
  * The purpose of this class is to allow one to load and execute
 35  
  * Screen modules.
 36  
  *
 37  
  * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a>
 38  
  * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
 39  
  * @version $Id: ScreenLoader.java,v 1.10.2.3 2004/08/16 22:57:50 henning Exp $
 40  
  */
 41  
 public class ScreenLoader
 42  
     extends GenericLoader
 43  
     implements Loader
 44  
 {
 45  
     /** Logging */
 46  34
     private static Log log = LogFactory.getLog(ScreenLoader.class);
 47  
 
 48  
     /** The single instance of this class. */
 49  17
     private static ScreenLoader instance =
 50  
         new ScreenLoader(Turbine.getConfiguration()
 51  
                          .getInt(TurbineConstants.SCREEN_CACHE_SIZE_KEY,
 52  
                                  TurbineConstants.SCREEN_CACHE_SIZE_DEFAULT));
 53  
 
 54  
     /** The Assembler Broker Service */
 55  17
     private static AssemblerBrokerService ab = TurbineAssemblerBroker.getService();
 56  
 
 57  
     /**
 58  
      * These ctor's are private to force clients to use getInstance()
 59  
      * to access this class.
 60  
      */
 61  
     private ScreenLoader()
 62  
     {
 63  0
         super();
 64  0
     }
 65  
 
 66  
     /**
 67  
      * These ctor's are private to force clients to use getInstance()
 68  
      * to access this class.
 69  
      */
 70  
     private ScreenLoader(int i)
 71  
     {
 72  17
         super(i);
 73  17
     }
 74  
 
 75  
     /**
 76  
      * Adds an instance of an object into the hashtable.
 77  
      *
 78  
      * @param name Name of object.
 79  
      * @param screen Screen to be associated with name.
 80  
      */
 81  
     private void addInstance(String name, Screen screen)
 82  
     {
 83  0
         if (cache())
 84  
         {
 85  0
             this.put(name, (Screen) screen);
 86  
         }
 87  0
     }
 88  
 
 89  
     /**
 90  
      * Attempts to load and execute the external Screen. This is used
 91  
      * when you want to execute a Screen which returns its output via
 92  
      * a MultiPartElement instead of out the data.getPage() value.
 93  
      * This allows you to easily chain the execution of Screen modules
 94  
      * together.
 95  
      *
 96  
      * @param data Turbine information.
 97  
      * @param name Name of object that will execute the screen.
 98  
      * @exception Exception a generic exception.
 99  
      */
 100  
     public ConcreteElement eval(RunData data, String name)
 101  
             throws Exception
 102  
     {
 103  
         // Execute screen
 104  0
         return getInstance(name).build(data);
 105  
     }
 106  
 
 107  
     /**
 108  
      * Attempts to load and execute the Screen. This is used when you
 109  
      * want to execute a Screen which returns its output via the
 110  
      * data.getPage() object.
 111  
      *
 112  
      * @param data Turbine information.
 113  
      * @param name Name of object that will execute the screen.
 114  
      * @exception Exception a generic exception.
 115  
      */
 116  
     public void exec(RunData data, String name)
 117  
             throws Exception
 118  
     {
 119  0
         this.eval(data, name);
 120  0
     }
 121  
 
 122  
     /**
 123  
      * Pulls out an instance of the object by name.  Name is just the
 124  
      * single name of the object. This is equal to getInstance but
 125  
      * returns an Assembler object and is needed to fulfil the Loader
 126  
      * interface.
 127  
      *
 128  
      * @param name Name of object instance.
 129  
      * @return A Screen with the specified name, or null.
 130  
      * @exception Exception a generic exception.
 131  
      */
 132  
     public Assembler getAssembler(String name)
 133  
         throws Exception
 134  
     {
 135  23
         return getInstance(name);
 136  
     }
 137  
 
 138  
     /**
 139  
      * Pulls out an instance of the Screen by name.  Name is just the
 140  
      * single name of the Screen.
 141  
      *
 142  
      * @param name Name of requested Screen.
 143  
      * @return A Screen with the specified name, or null.
 144  
      * @exception Exception a generic exception.
 145  
      */
 146  
     public Screen getInstance(String name)
 147  
             throws Exception
 148  
     {
 149  23
         Screen screen = null;
 150  
 
 151  
         // Check if the screen is already in the cache
 152  23
         if (cache() && this.containsKey(name))
 153  
         {
 154  0
             screen = (Screen) this.get(name);
 155  0
             log.debug("Found Screen " + name + " in the cache!");
 156  
         }
 157  
         else
 158  
         {
 159  23
             log.debug("Loading Screen " + name + " from the Assembler Broker");
 160  
 
 161  
             try
 162  
             {
 163  23
                 if (ab != null)
 164  
                 {
 165  
                     // Attempt to load the screen
 166  23
                     screen = (Screen) ab.getAssembler(
 167  
                         AssemblerBrokerService.SCREEN_TYPE, name);
 168  
                 }
 169  
             }
 170  0
             catch (ClassCastException cce)
 171  
             {
 172  
                 // This can alternatively let this exception be thrown
 173  
                 // So that the ClassCastException is shown in the
 174  
                 // browser window.  Like this it shows "Screen not Found"
 175  0
                 screen = null;
 176  23
             }
 177  
 
 178  23
             if (screen == null)
 179  
             {
 180  
                 // If we did not find a screen we should try and give
 181  
                 // the user a reason for that...
 182  
                 // FIX ME: The AssemblerFactories should each add it's
 183  
                 // own string here...
 184  19
                 List packages = Turbine.getConfiguration()
 185  
                     .getList(TurbineConstants.MODULE_PACKAGES);
 186  
 
 187  19
                 ObjectUtils.addOnce(packages,
 188  
                         GenericLoader.getBasePackage());
 189  
 
 190  19
                 throw new ClassNotFoundException(
 191  
                         "\n\n\tRequested Screen not found: " + name +
 192  
                         "\n\tTurbine looked in the following " +
 193  
                         "modules.packages path: \n\t" + packages.toString() + "\n");
 194  
             }
 195  4
             else if (cache())
 196  
             {
 197  
                 // The new instance is added to the cache
 198  0
                 addInstance(name, screen);
 199  
             }
 200  
         }
 201  4
         return screen;
 202  
     }
 203  
 
 204  
     /**
 205  
      * The method through which this class is accessed.
 206  
      *
 207  
      * @return The single instance of this class.
 208  
      */
 209  
     public static ScreenLoader getInstance()
 210  
     {
 211  18
         return instance;
 212  
     }
 213  
 }

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