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1   /***************************************************************************************
2    * Copyright (c) Jonas BonŽr, Alexandre Vasseur. All rights reserved.                 *
3    * http://aspectwerkz.codehaus.org                                                    *
4    * ---------------------------------------------------------------------------------- *
5    * The software in this package is published under the terms of the LGPL license      *
6    * a copy of which has been included with this distribution in the license.txt file.  *
7    **************************************************************************************/
8   package org.codehaus.aspectwerkz.transform.inlining;
9   
10  import java.util.StringTokenizer;
11  
12  import org.codehaus.aspectwerkz.util.ContextClassLoader;
13  import org.codehaus.aspectwerkz.util.ContextClassLoader;
14  import org.codehaus.aspectwerkz.transform.inlining.spi.AspectModel;
15  import org.codehaus.aspectwerkz.definition.AspectDefinition;
16  import org.codehaus.aspectwerkz.reflect.ClassInfo;
17  import org.codehaus.aspectwerkz.exception.DefinitionException;
18  
19  /***
20   * Manages the different aspect model implementations that is registered.
21   *
22   * @author <a href="mailto:jboner@codehaus.org">Jonas BonŽr </a>
23   */
24  public class AspectModelManager {
25  
26      public static final String ASPECT_MODELS_VM_OPTION = "aspectwerkz.extension.aspectmodels";
27      private static final String DELIMITER = ":";
28  
29      /***
30       * The aspects models that are registered
31       */
32      private static AspectModel[] ASPECT_MODELS = new AspectModel[]{};
33  
34      static {
35          registerAspectModels(System.getProperty(ASPECT_MODELS_VM_OPTION, null));
36      }
37  
38      /***
39       * Returns an array with all the aspect models that has been registered.
40       *
41       * @return an array with the aspect models
42       */
43      public static AspectModel[] getModels() {
44          return ASPECT_MODELS;
45      }
46  
47      /***
48       * Returns the advice model for a specific aspect model type id.
49       *
50       * @param type the aspect model type id
51       * @return the aspect model
52       */
53      public static AspectModel getModelFor(String type) {
54          for (int i = 0; i < ASPECT_MODELS.length; i++) {
55              AspectModel aspectModel = ASPECT_MODELS[i];
56              if (aspectModel.getAspectModelType().equals(type)) {
57                  return aspectModel;
58              }
59          }
60          return null;
61      }
62  
63      /***
64       * Let all aspect models try to define the aspect (only one will succeed).
65       *
66       * @param aspectClassInfo
67       * @param aspectDef
68       * @param loader
69       */
70      public static void defineAspect(final ClassInfo aspectClassInfo,
71                                      final AspectDefinition aspectDef,
72                                      final ClassLoader loader) {
73          for (int i = 0; i < ASPECT_MODELS.length; i++) {
74              ASPECT_MODELS[i].defineAspect(aspectClassInfo, aspectDef, loader);
75          }
76      }
77  
78      /***
79       * Registers aspect models.
80       *
81       * @param aspectModels the class names of the aspect models to register concatenated and separated with a ':'.
82       */
83      private static void registerAspectModels(final String aspectModels) {
84          if (aspectModels != null) {
85              StringTokenizer tokenizer = new StringTokenizer(aspectModels, DELIMITER);
86              ASPECT_MODELS = new AspectModel[tokenizer.countTokens()];
87              for (int i = 0; i < ASPECT_MODELS.length; i++) {
88                  final String className = tokenizer.nextToken();
89                  try {
90                      final Class modelClass = ContextClassLoader.forName(className);
91                      ASPECT_MODELS[i] = (AspectModel) modelClass.newInstance();
92                  } catch (ClassNotFoundException e) {
93                      throw new DefinitionException(
94                              "aspect model implementation class not found [" +
95                              className + "]: " + e.toString()
96                      );
97                  } catch (Exception e) {
98                      throw new DefinitionException(
99                              "aspect model implementation class could not be instantiated [" +
100                             className +
101                             "] - make sure it has a default no argument constructor: " +
102                             e.toString()
103                     );
104                 }
105             }
106         }
107     }
108 }