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Java > Open Source Codes > org > apache > tapestry > enhance > InjectObjectWorker


1 // Copyright 2004, 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.lang.reflect.Modifier JavaDoc;
18
19 import org.apache.hivemind.ApplicationRuntimeException;
20 import org.apache.hivemind.Location;
21 import org.apache.hivemind.service.MethodSignature;
22 import org.apache.hivemind.util.Defense;
23 import org.apache.tapestry.services.InjectedValueProvider;
24 import org.apache.tapestry.spec.InjectSpecification;
25
26 /**
27  * Implementation for injection type "object" (the default). Adds read-only properties to the
28  * enhanced class that contain objects injected from HiveMind.
29  *
30  * @author Howard M. Lewis Ship
31  * @since 4.0
32  */
33 public class InjectObjectWorker implements InjectEnhancementWorker
34 {
35     private InjectedValueProvider _provider;
36
37     public void performEnhancement(EnhancementOperation op, InjectSpecification is)
38     {
39         String JavaDoc name = is.getProperty();
40         String JavaDoc objectReference = is.getObject();
41         Location location = is.getLocation();
42
43         injectObject(op, objectReference, name, location);
44     }
45
46     public void injectObject(EnhancementOperation op, String JavaDoc objectReference, String JavaDoc propertyName,
47             Location location)
48     {
49         Defense.notNull(op, "op");
50         Defense.notNull(propertyName, "propertyName");
51         Defense.notNull(objectReference, "objectReference");
52
53         Class JavaDoc propertyType = op.getPropertyType(propertyName);
54         if (propertyType == null)
55             propertyType = Object JavaDoc.class;
56
57         op.claimProperty(propertyName);
58
59         Object JavaDoc injectedValue = _provider.obtainValue(objectReference, location);
60
61         if (injectedValue == null)
62             throw new ApplicationRuntimeException(EnhanceMessages
63                     .locatedValueIsNull(objectReference), location, null);
64
65         if (!propertyType.isAssignableFrom(injectedValue.getClass()))
66             throw new ApplicationRuntimeException(EnhanceMessages.incompatibleInjectType(
67                     objectReference,
68                     injectedValue,
69                     propertyType), location, null);
70
71         String JavaDoc fieldName = op.addInjectedField("_$" + propertyName, propertyType, injectedValue);
72
73         String JavaDoc methodName = EnhanceUtils.createAccessorMethodName(propertyName);
74
75         op.addMethod(
76                 Modifier.PUBLIC,
77                 new MethodSignature(propertyType, methodName, null, null),
78                 "return " + fieldName + ";");
79     }
80
81     public void setProvider(InjectedValueProvider provider)
82     {
83         _provider = provider;
84     }
85 }
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