Coverage report

  %line %branch
org.apache.turbine.modules.ScreenLoader
62% 
88% 

 1  
 package org.apache.turbine.modules;
 2  
 
 3  
 /*
 4  
  * Copyright 2001-2005 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 264148 2005-08-29 14:21:04Z henning $
 40  
  */
 41  21
 public class ScreenLoader
 42  
     extends GenericLoader
 43  
     implements Loader
 44  
 {
 45  
     /** Serial Version UID */
 46  
     private static final long serialVersionUID = -4825216334500657398L;
 47  
 
 48  
     /** Logging */
 49  84
     private static Log log = LogFactory.getLog(ScreenLoader.class);
 50  
 
 51  
     /** The single instance of this class. */
 52  42
     private static ScreenLoader instance =
 53  
         new ScreenLoader(Turbine.getConfiguration()
 54  
                          .getInt(TurbineConstants.SCREEN_CACHE_SIZE_KEY,
 55  
                                  TurbineConstants.SCREEN_CACHE_SIZE_DEFAULT));
 56  
 
 57  
     /** The Assembler Broker Service */
 58  42
     private static AssemblerBrokerService ab = TurbineAssemblerBroker.getService();
 59  
 
 60  
     /**
 61  
      * These ctor's are private to force clients to use getInstance()
 62  
      * to access this class.
 63  
      */
 64  
     private ScreenLoader()
 65  
     {
 66  0
         super();
 67  0
     }
 68  
 
 69  
     /**
 70  
      * These ctor's are private to force clients to use getInstance()
 71  
      * to access this class.
 72  
      */
 73  
     private ScreenLoader(int i)
 74  
     {
 75  42
         super(i);
 76  42
     }
 77  
 
 78  
     /**
 79  
      * Adds an instance of an object into the hashtable.
 80  
      *
 81  
      * @param name Name of object.
 82  
      * @param screen Screen to be associated with name.
 83  
      */
 84  
     private void addInstance(String name, Screen screen)
 85  
     {
 86  0
         if (cache())
 87  
         {
 88  0
             this.put(name, (Screen) screen);
 89  
         }
 90  0
     }
 91  
 
 92  
     /**
 93  
      * Attempts to load and execute the external Screen. This is used
 94  
      * when you want to execute a Screen which returns its output via
 95  
      * a MultiPartElement instead of out the data.getPage() value.
 96  
      * This allows you to easily chain the execution of Screen modules
 97  
      * together.
 98  
      *
 99  
      * @param data Turbine information.
 100  
      * @param name Name of object that will execute the screen.
 101  
      * @exception Exception a generic exception.
 102  
      */
 103  
     public ConcreteElement eval(RunData data, String name)
 104  
             throws Exception
 105  
     {
 106  
         // Execute screen
 107  0
         return getInstance(name).build(data);
 108  
     }
 109  
 
 110  
     /**
 111  
      * Attempts to load and execute the Screen. This is used when you
 112  
      * want to execute a Screen which returns its output via the
 113  
      * data.getPage() object.
 114  
      *
 115  
      * @param data Turbine information.
 116  
      * @param name Name of object that will execute the screen.
 117  
      * @exception Exception a generic exception.
 118  
      */
 119  
     public void exec(RunData data, String name)
 120  
             throws Exception
 121  
     {
 122  0
         this.eval(data, name);
 123  0
     }
 124  
 
 125  
     /**
 126  
      * Pulls out an instance of the object by name.  Name is just the
 127  
      * single name of the object. This is equal to getInstance but
 128  
      * returns an Assembler object and is needed to fulfil the Loader
 129  
      * interface.
 130  
      *
 131  
      * @param name Name of object instance.
 132  
      * @return A Screen with the specified name, or null.
 133  
      * @exception Exception a generic exception.
 134  
      */
 135  
     public Assembler getAssembler(String name)
 136  
         throws Exception
 137  
     {
 138  46
         return getInstance(name);
 139  
     }
 140  
 
 141  
     /**
 142  
      * Pulls out an instance of the Screen by name.  Name is just the
 143  
      * single name of the Screen.
 144  
      *
 145  
      * @param name Name of requested Screen.
 146  
      * @return A Screen with the specified name, or null.
 147  
      * @exception Exception a generic exception.
 148  
      */
 149  
     public Screen getInstance(String name)
 150  
             throws Exception
 151  
     {
 152  46
         Screen screen = null;
 153  
 
 154  
         // Check if the screen is already in the cache
 155  46
         if (cache() && this.containsKey(name))
 156  
         {
 157  0
             screen = (Screen) this.get(name);
 158  0
             log.debug("Found Screen " + name + " in the cache!");
 159  
         }
 160  
         else
 161  
         {
 162  46
             log.debug("Loading Screen " + name + " from the Assembler Broker");
 163  
 
 164  
             try
 165  
             {
 166  46
                 if (ab != null)
 167  
                 {
 168  
                     // Attempt to load the screen
 169  46
                     screen = (Screen) ab.getAssembler(
 170  
                         AssemblerBrokerService.SCREEN_TYPE, name);
 171  
                 }
 172  23
             }
 173  0
             catch (ClassCastException cce)
 174  
             {
 175  
                 // This can alternatively let this exception be thrown
 176  
                 // So that the ClassCastException is shown in the
 177  
                 // browser window.  Like this it shows "Screen not Found"
 178  0
                 screen = null;
 179  23
             }
 180  
 
 181  46
             if (screen == null)
 182  
             {
 183  
                 // If we did not find a screen we should try and give
 184  
                 // the user a reason for that...
 185  
                 // FIX ME: The AssemblerFactories should each add it's
 186  
                 // own string here...
 187  38
                 List packages = Turbine.getConfiguration()
 188  
                     .getList(TurbineConstants.MODULE_PACKAGES);
 189  
 
 190  38
                 ObjectUtils.addOnce(packages,
 191  
                         GenericLoader.getBasePackage());
 192  
 
 193  38
                 throw new ClassNotFoundException(
 194  
                         "\n\n\tRequested Screen not found: " + name +
 195  
                         "\n\tTurbine looked in the following " +
 196  
                         "modules.packages path: \n\t" + packages.toString() + "\n");
 197  
             }
 198  8
             else if (cache())
 199  
             {
 200  
                 // The new instance is added to the cache
 201  0
                 addInstance(name, screen);
 202  
             }
 203  
         }
 204  8
         return screen;
 205  
     }
 206  
 
 207  
     /**
 208  
      * The method through which this class is accessed.
 209  
      *
 210  
      * @return The single instance of this class.
 211  
      */
 212  
     public static ScreenLoader getInstance()
 213  
     {
 214  44
         return instance;
 215  
     }
 216  
 }

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