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Java > Open Source Codes > com > sun > facelets > tag > MetaTagHandler


1 /**
2  * Licensed under the Common Development and Distribution License,
3  * you may not use this file except in compliance with the License.
4  * You may obtain a copy of the License at
5  *
6  * http://www.sun.com/cddl/
7  *
8  * Unless required by applicable law or agreed to in writing, software
9  * distributed under the License is distributed on an "AS IS" BASIS,
10  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
11  * implied. See the License for the specific language governing
12  * permissions and limitations under the License.
13  */
14
15 package com.sun.facelets.tag;
16
17 import com.sun.facelets.FaceletContext;
18 import com.sun.facelets.util.ParameterCheck;
19
20 /**
21  * A base tag for wiring state to an object instance based on rules populated at
22  * the time of creating a MetaRuleset.
23  *
24  * @author Jacob Hookom
25  * @version $Id: MetaTagHandler.java,v 1.2 2005/08/24 04:38:47 jhook Exp $
26  */
27 public abstract class MetaTagHandler extends TagHandler {
28
29     private Class JavaDoc lastType = Object JavaDoc.class;
30
31     private Metadata mapper;
32
33     public MetaTagHandler(TagConfig config) {
34         super(config);
35     }
36
37     /**
38      * Extend this method in order to add your own rules.
39      *
40      * @param type
41      * @return
42      */
43     protected MetaRuleset createMetaRuleset(Class JavaDoc type) {
44         ParameterCheck.notNull("type", type);
45         return new MetaRulesetImpl(this.tag, type);
46     }
47
48     /**
49      * Invoking/extending this method will cause the results of the created
50      * MetaRuleset to auto-wire state to the passed instance.
51      *
52      * @param ctx
53      * @param instance
54      */
55     protected void setAttributes(FaceletContext ctx, Object JavaDoc instance) {
56         if (instance != null) {
57             Class JavaDoc type = instance.getClass();
58             if (mapper == null || !this.lastType.equals(type)) {
59                 this.lastType = type;
60                 this.mapper = this.createMetaRuleset(type).finish();
61             }
62             this.mapper.applyMetadata(ctx, instance);
63         }
64     }
65 }
66
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