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Java > Open Source Codes > org > apache > tapestry > binding > BeanBinding


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.binding;
16
17 import org.apache.hivemind.Location;
18 import org.apache.hivemind.util.Defense;
19 import org.apache.tapestry.IComponent;
20 import org.apache.tapestry.coerce.ValueConverter;
21
22 /**
23  * Binding whose value is a named bean provided by a component.
24  *
25  * @author Howard M. Lewis Ship
26  * @since 4.0
27  */
28 public class BeanBinding extends AbstractBinding
29 {
30     private final IComponent _component;
31
32     private final String JavaDoc _beanName;
33
34     public BeanBinding(String JavaDoc description, ValueConverter valueConverter, Location location,
35             IComponent component, String JavaDoc beanName)
36     {
37         super(description, valueConverter, location);
38
39         Defense.notNull(component, "component");
40         Defense.notNull(beanName, "beanName");
41
42         _component = component;
43         _beanName = beanName;
44     }
45
46     /**
47      * Beans obtained via the binding should *not* be cached by the component because beans may be
48      * discarded inside the {@link org.apache.tapestry.bean.BeanProvider} based on the life cycle of
49      * the bean. The BeanProvider caches beans as well.
50      */
51
52     public boolean isInvariant()
53     {
54         return false;
55     }
56
57     public Object JavaDoc getComponent()
58     {
59         return _component;
60     }
61
62     public Object JavaDoc getObject()
63     {
64         return _component.getBeans().getBean(_beanName);
65     }
66
67 }
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