001 /* $Id: FinderFromDfltResource.java 992060 2010-09-02 19:09:47Z simonetripodi $
002 *
003 * Licensed to the Apache Software Foundation (ASF) under one or more
004 * contributor license agreements. See the NOTICE file distributed with
005 * this work for additional information regarding copyright ownership.
006 * The ASF licenses this file to You under the Apache License, Version 2.0
007 * (the "License"); you may not use this file except in compliance with
008 * the License. You may obtain a copy of the License at
009 *
010 * http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing, software
013 * distributed under the License is distributed on an "AS IS" BASIS,
014 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
015 * See the License for the specific language governing permissions and
016 * limitations under the License.
017 */
018 package org.apache.commons.digester.plugins.strategies;
019
020 import java.io.InputStream;
021 import java.util.Properties;
022
023 import org.apache.commons.digester.Digester;
024 import org.apache.commons.digester.plugins.RuleFinder;
025 import org.apache.commons.digester.plugins.RuleLoader;
026 import org.apache.commons.digester.plugins.PluginException;
027
028 /**
029 * A rule-finding algorithm which looks for a resource file in the classpath
030 * whose name is derived from the plugin class name plus a specified suffix.
031 * <p>
032 * If the resource-file is found, then it is expected to define a set of
033 * Digester rules in xmlrules format.
034 *
035 * @since 1.6
036 */
037
038 public class FinderFromDfltResource extends RuleFinder {
039 public static String DFLT_RESOURCE_SUFFIX = "RuleInfo.xml";
040
041 private String resourceSuffix;
042
043 /** See {@link #findLoader}. */
044 public FinderFromDfltResource() {
045 this(DFLT_RESOURCE_SUFFIX);
046 }
047
048 /**
049 * Create a rule-finder which can load an xmlrules file, cache
050 * the rules away, and later add them as a plugin's custom rules
051 * when that plugin is referenced.
052 *
053 * @param resourceSuffix must be non-null.
054 */
055 public FinderFromDfltResource(String resourceSuffix) {
056 this.resourceSuffix = resourceSuffix;
057 }
058
059 /**
060 * If there exists a resource file whose name is equal to the plugin
061 * class name + the suffix specified in the constructor, then
062 * load that file, run it through the xmlrules module and return an object
063 * encapsulating those rules.
064 * <p>
065 * If there is no such resource file, then just return null.
066 * <p>
067 * The returned object (when non-null) will add the selected rules to
068 * the digester whenever its addRules method is invoked.
069 */
070 @Override
071 public RuleLoader findLoader(Digester d, Class<?> pluginClass, Properties p)
072 throws PluginException {
073
074 String resourceName =
075 pluginClass.getName().replace('.', '/')
076 + resourceSuffix;
077
078 InputStream is =
079 pluginClass.getClassLoader().getResourceAsStream(
080 resourceName);
081
082 if (is == null) {
083 // ok, no such resource
084 return null;
085 }
086
087 return FinderFromResource.loadRules(d, pluginClass, is, resourceName);
088 }
089 }
090