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16 package org.apache.commons.chain.config;
17
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19 import org.apache.commons.digester.Rule;
20 import org.xml.sax.Attributes;
21
22
23 /***
24 * <p>Digester rule that will dynamically register a new set of rules
25 * for a specified element name and default implementation class. This
26 * allows "alias" elements to be created for {@link Chain} and {@link Command}
27 * implementation classes that are commonly used. Besides factoring out
28 * the class names to make changes easier, this also makes configuration
29 * files <strong>much</strong> easier to read and write.</p>
30 *
31 * @version $Revision: 155403 $ $Date: 2005-02-26 12:52:46 +0000 (Sat, 26 Feb 2005) $
32 */
33
34 class ConfigDefineRule extends Rule {
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38
39
40 /***
41 * <p>Construct a new instance of this rule that will in turn
42 * dynamically register appropriate rules for a new alias element.</p>
43 *
44 * @param nameAttribute Name of the attribute containing the name
45 * of the new element for which rules should generated
46 * @param classAttribute Name of the attribute containing the
47 * implementation class for the new chain or command
48 */
49 public ConfigDefineRule(String nameAttribute, String classAttribute) {
50 super();
51 this.nameAttribute = nameAttribute;
52 this.classAttribute = classAttribute;
53 }
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57
58
59 /***
60 * <p>The name of the attribute under which we can retrieve the
61 * fully qualified class name of the implementation class for this
62 * new element.</p>
63 */
64 private String classAttribute = null;
65
66
67 /***
68 * <p>The name of the attribute under which we can retrieve the name
69 * this element for which rules should be created.</p>
70 */
71 private String nameAttribute = null;
72
73
74
75
76
77 /***
78 * <p>Register new rules for the specified name and class.</p>
79 *
80 * @param namespace the namespace URI of the matching element, or an
81 * empty string if the parser is not namespace aware or the element has
82 * no namespace
83 * @param name the local name if the parser is namespace aware, or just
84 * the element name otherwise
85 * @param attributes The attribute list of this element
86 */
87 public void begin(String namespace, String name, Attributes attributes)
88 throws Exception {
89
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91 String nameValue = attributes.getValue(nameAttribute);
92 String classValue = attributes.getValue(classAttribute);
93
94
95 digester.addObjectCreate("*/" + nameValue, classValue);
96 digester.addSetProperties("*/" + nameValue);
97 digester.addRule("*/" + nameValue,
98 new ConfigRegisterRule(nameAttribute));
99
100 }
101
102
103 }