| package org.apache.commons.digester3.plugins.strategies; |
| |
| /* |
| * 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; |
| import org.apache.commons.digester3.plugins.PluginException; |
| import org.apache.commons.digester3.plugins.RuleFinder; |
| import org.apache.commons.digester3.plugins.RuleLoader; |
| |
| /** |
| * A rule-finding algorithm which expects the caller to specify a methodname as a plugin property, where the method |
| * exists on the plugin class. |
| * |
| * @since 1.6 |
| */ |
| public class FinderFromMethod |
| extends RuleFinder |
| { |
| |
| /** |
| * Default XML attribute that needs to be present on a plugin declaration in order to specify the method |
| * to load rules from. |
| */ |
| private static final String DFLT_METHOD_ATTR = "method"; |
| |
| /** See {@link #findLoader}. */ |
| private final String methodAttr; |
| |
| /** Constructor. */ |
| public FinderFromMethod() |
| { |
| this( DFLT_METHOD_ATTR ); |
| } |
| |
| /** |
| * See {@link #findLoader}. |
| * |
| * @param methodAttr The XML attribute that needs to be present on a plugin declaration in order to specify the |
| * method to load rules from. |
| */ |
| public FinderFromMethod( final String methodAttr ) |
| { |
| this.methodAttr = methodAttr; |
| } |
| |
| /** |
| * If there exists a property with the name matching constructor param methodAttr, then locate the appropriate |
| * Method on the plugin class and return an object encapsulating that info. |
| * <p> |
| * If there is no matching property provided, then just return null. |
| * <p> |
| * The returned object (when non-null) will invoke the target method on the plugin class whenever its addRules |
| * method is invoked. The target method is expected to have the following prototype: |
| * <code> public static void xxxxx(Digester d, String patternPrefix); </code> |
| * |
| * @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. |
| */ |
| @Override |
| public RuleLoader findLoader( final Digester d, final Class<?> pluginClass, final Properties p ) |
| throws PluginException |
| { |
| |
| final String methodName = p.getProperty( methodAttr ); |
| if ( methodName == null ) |
| { |
| // nope, user hasn't requested dynamic rules to be loaded |
| // from a specific class. |
| return null; |
| } |
| |
| return new LoaderFromClass( pluginClass, methodName ); |
| } |
| |
| } |