| package org.apache.commons.digester3.plugins; |
| |
| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, |
| * software distributed under the License is distributed on an |
| * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
| * KIND, either express or implied. See the License for the |
| * specific language governing permissions and limitations |
| * under the License. |
| */ |
| |
| import java.util.Properties; |
| |
| import org.apache.commons.digester3.Digester; |
| |
| /** |
| * Each concrete implementation of RuleFinder is an algorithm for locating a source of digester rules for a plugin. The |
| * algorithm may use info explicitly provided by the user as part of the plugin declaration, or not (in which case the |
| * concrete RuleFinder subclass typically has Dflt as part of its name). |
| * <p> |
| * Instances of this class can also be regarded as a Factory for RuleLoaders, except that an instance of a RuleLoader is |
| * only created if the particular finder algorithm can locate a suitable source of rules given the plugin class and |
| * associated properties. |
| * <p> |
| * This is an abstract class rather than an interface in order to make it possible to enhance this class in future |
| * without breaking binary compatibility; it is possible to add methods to an abstract class, but not to an interface. |
| * |
| * @since 1.6 |
| */ |
| public abstract class RuleFinder |
| { |
| |
| /** |
| * Apply the finder algorithm to attempt to locate a source of digester rules for the specified plugin class. |
| * <p> |
| * This method is invoked when a plugin is declared by the user, either via an explicit use of |
| * PluginDeclarationRule, or implicitly via an "inline declaration" where the declaration and use are simultaneous. |
| * <p> |
| * If dynamic rules for the specified plugin class are located, then the RuleFinder will return a RuleLoader object |
| * encapsulating those rules, and this object will be invoked each time the user actually requests an instance of |
| * the declared plugin class, to load the custom rules associated with that plugin instance. |
| * <p> |
| * If no dynamic rules can be found, null is returned. This is not an error; merely an indication that this |
| * particular algorithm found no matches. |
| * <p> |
| * The properties object holds any xml attributes the user may have specified on the plugin declaration in order to |
| * indicate how to locate the plugin rules. |
| * <p> |
| * |
| * @param d The digester instance where locating plugin classes |
| * @param pluginClass The plugin Java class |
| * @param p The properties object that holds any xml attributes the user may have specified on the plugin |
| * declaration in order to indicate how to locate the plugin rules. |
| * @return a source of digester rules for the specified plugin class. |
| * @throws PluginException if the algorithm finds a source of rules, but there is something invalid |
| * about that source. |
| */ |
| public abstract RuleLoader findLoader( Digester d, Class<?> pluginClass, Properties p ) |
| throws PluginException; |
| |
| } |