org.apache.commons.digester.plugins.strategies.FinderFromMethod Maven / Gradle / Ivy
/* $Id: FinderFromMethod.java 729125 2008-12-23 21:21:07Z rahul $
*
* 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.
*/
package org.apache.commons.digester.plugins.strategies;
import java.util.Properties;
import org.apache.commons.digester.Digester;
import org.apache.commons.digester.plugins.RuleFinder;
import org.apache.commons.digester.plugins.RuleLoader;
import org.apache.commons.digester.plugins.PluginException;
/**
* 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 {
/**
* Xml attribute that needs to be present on a plugin declaration
* in order to specify the method to load rules from.
*/
public static String DFLT_METHOD_ATTR = "method";
/** See {@link #findLoader}. */
private String methodAttr;
/** Constructor. */
public FinderFromMethod() {
this(DFLT_METHOD_ATTR);
}
/** See {@link #findLoader}. */
public FinderFromMethod(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.
*
* If there is no matching property provided, then just return null.
*
* 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:
* public static void xxxxx(Digester d, String patternPrefix);
*/
public RuleLoader findLoader(Digester d, Class pluginClass, Properties p)
throws PluginException {
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);
}
}