- /* $Id: LoaderFromClass.java,v 1.5 2004/05/10 06:34:01 skitching Exp $
- *
- * Copyright 2004 The Apache Software Foundation.
- *
- * Licensed 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.lang.reflect.Method;
-
- import org.apache.commons.digester.Digester;
- import org.apache.commons.beanutils.MethodUtils;
- import org.apache.commons.logging.Log;
- import org.apache.commons.digester.plugins.RuleLoader;
- import org.apache.commons.digester.plugins.PluginException;
-
- /**
- * A RuleLoader which invokes a static method on a target class, leaving that
- * method to actually instantiate and add new rules to a Digester instance.
- *
- * @since 1.6
- */
-
- public class LoaderFromClass extends RuleLoader {
-
- private Class rulesClass;
- private Method rulesMethod;
-
- /** Constructor. */
- public LoaderFromClass(Class rulesClass, Method rulesMethod) {
- this.rulesClass = rulesClass;
- this.rulesMethod = rulesMethod;
- }
-
- /** Constructor. */
- public LoaderFromClass(Class rulesClass, String methodName)
- throws PluginException {
-
- Method method = locateMethod(rulesClass, methodName);
-
- if (method == null) {
- throw new PluginException(
- "rule class " + rulesClass.getName()
- + " does not have method " + methodName
- + " or that method has an invalid signature.");
- }
-
- this.rulesClass = rulesClass;
- this.rulesMethod = method;
- }
-
- /**
- * Just invoke the target method.
- */
- public void addRules(Digester d, String path) throws PluginException {
- Log log = d.getLogger();
- boolean debug = log.isDebugEnabled();
- if (debug) {
- log.debug(
- "LoaderFromClass loading rules for plugin at path ["
- + path + "]");
- }
-
- try {
- Object[] params = {d, path};
- Object none = rulesMethod.invoke(null, params);
- } catch (Exception e) {
- throw new PluginException(
- "Unable to invoke rules method " + rulesMethod
- + " on rules class " + rulesClass, e);
- }
- }
-
- /**
- * Find a method on the specified class whose name matches methodName,
- * and whose signature is:
- * <code> public static void foo(Digester d, String patternPrefix);</code>.
- *
- * @return null if no such method exists.
- */
- public static Method locateMethod(Class rulesClass, String methodName)
- throws PluginException {
-
- Class[] paramSpec = { Digester.class, String.class };
- Method rulesMethod = MethodUtils.getAccessibleMethod(
- rulesClass, methodName, paramSpec);
-
- return rulesMethod;
- }
- }
-