01: /* $Id: FinderFromDfltMethod.java 471661 2006-11-06 08:09:25Z skitching $
02: *
03: * Licensed to the Apache Software Foundation (ASF) under one or more
04: * contributor license agreements. See the NOTICE file distributed with
05: * this work for additional information regarding copyright ownership.
06: * The ASF licenses this file to You under the Apache License, Version 2.0
07: * (the "License"); you may not use this file except in compliance with
08: * the License. You may obtain a copy of the License at
09: *
10: * http://www.apache.org/licenses/LICENSE-2.0
11: *
12: * Unless required by applicable law or agreed to in writing, software
13: * distributed under the License is distributed on an "AS IS" BASIS,
14: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15: * See the License for the specific language governing permissions and
16: * limitations under the License.
17: */
18:
19: package org.apache.commons.digester.plugins.strategies;
20:
21: import java.util.Properties;
22: import java.lang.reflect.Method;
23:
24: import org.apache.commons.digester.Digester;
25: import org.apache.commons.digester.plugins.RuleFinder;
26: import org.apache.commons.digester.plugins.RuleLoader;
27: import org.apache.commons.digester.plugins.PluginException;
28:
29: /**
30: * A rule-finding algorithm which looks for a method with a specific name
31: * on the plugin class.
32: *
33: * @since 1.6
34: */
35:
36: public class FinderFromDfltMethod extends RuleFinder {
37: public static String DFLT_METHOD_NAME = "addRules";
38:
39: private String methodName;
40:
41: /** See {@link #findLoader}. */
42: public FinderFromDfltMethod() {
43: this (DFLT_METHOD_NAME);
44: }
45:
46: /**
47: * Create a rule-finder which invokes a specific method on the plugin
48: * class whenever dynamic rules for a plugin need to be loaded. See the
49: * findRules method for more info.
50: *
51: * @param methodName must be non-null.
52: */
53: public FinderFromDfltMethod(String methodName) {
54: this .methodName = methodName;
55: }
56:
57: /**
58: * If there exists on the plugin class a method with name matching the
59: * constructor's methodName value then locate the appropriate Method on
60: * the plugin class and return an object encapsulating that info.
61: * <p>
62: * If there is no matching method then just return null.
63: * <p>
64: * The returned object (when non-null) will invoke the target method
65: * on the plugin class whenever its addRules method is invoked. The
66: * target method is expected to have the following prototype:
67: * <code> public static void xxxxx(Digester d, String patternPrefix); </code>
68: */
69: public RuleLoader findLoader(Digester d, Class pluginClass,
70: Properties p) throws PluginException {
71:
72: Method rulesMethod = LoaderFromClass.locateMethod(pluginClass,
73: methodName);
74: if (rulesMethod == null) {
75: return null;
76: }
77:
78: return new LoaderFromClass(pluginClass, rulesMethod);
79: }
80: }
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