InjectAssetWorker


1   // Copyright 2005 The Apache Software Foundation
2   //
3   // Licensed under the Apache License, Version 2.0 (the "License");
4   // you may not use this file except in compliance with the License.
5   // You may obtain a copy of the License at
6   //
7   //     http://www.apache.org/licenses/LICENSE-2.0
8   //
9   // Unless required by applicable law or agreed to in writing, software
10  // distributed under the License is distributed on an "AS IS" BASIS,
11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12  // See the License for the specific language governing permissions and
13  // limitations under the License.
14  
15  package org.apache.tapestry.enhance;
16  
17  import java.util.Iterator  ;
18  
19  import org.apache.hivemind.ApplicationRuntimeException;
20  import org.apache.hivemind.ErrorLog;
21  import org.apache.hivemind.util.Defense;
22  import org.apache.tapestry.IAsset;
23  import org.apache.tapestry.IComponent;
24  import org.apache.tapestry.spec.IAssetSpecification;
25  import org.apache.tapestry.spec.IComponentSpecification;
26  
27  /**
28   * Injects assets as component properties.
29   * 
30   * @author Howard M. Lewis Ship
31   * @since 4.0
32   */
33  public class InjectAssetWorker implements EnhancementWorker
34  {
35      private ErrorLog _errorLog;
36  
37      public void performEnhancement(EnhancementOperation op, IComponentSpecification spec)
38      {
39          Iterator   i = spec.getAssetNames().iterator();
40          while (i.hasNext())
41          {
42              String   name = (String  ) i.next();
43  
44              IAssetSpecification as = spec.getAsset(name);
45  
46              String   propertyName = as.getPropertyName();
47  
48              if (propertyName != null)
49              {
50                  try
51                  {
52                      injectAsset(op, name, propertyName);
53                  }
54                  catch (Exception   ex)
55                  {
56                      _errorLog.error(EnhanceMessages.errorAddingProperty(propertyName, op
57                              .getBaseClass(), ex), as.getLocation(), ex);
58                  }
59              }
60          }
61      }
62  
63      public void injectAsset(EnhancementOperation op, String   assetName, String   propertyName)
64      {
65          Defense.notNull(op, "op");
66          Defense.notNull(assetName, "assetName");
67          Defense.notNull(propertyName, "propertyName");
68  
69          Class   propertyType = EnhanceUtils.extractPropertyType(op, propertyName, null);
70  
71          op.claimProperty(propertyName);
72  
73          if (!propertyType.isAssignableFrom(IAsset.class))
74              throw new ApplicationRuntimeException(EnhanceMessages.incompatiblePropertyType(
75                      propertyName,
76                      propertyType,
77                      IAsset.class));
78  
79          String   fieldName = "_$" + propertyName;
80  
81          op.addField(fieldName, propertyType);
82  
83          EnhanceUtils.createSimpleAccessor(op, fieldName, propertyName, propertyType);
84  
85          // i.e. _$fred = getAsset("barney");
86  
87          String   code = fieldName + " = getAsset(\"" + assetName + "\");";
88  
89          op.extendMethodImplementation(IComponent.class, EnhanceUtils.FINISH_LOAD_SIGNATURE, code);
90      }
91  
92      public void setErrorLog(ErrorLog errorLog)
93      {
94          _errorLog = errorLog;
95      }
96  }
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