| 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.io.FileInputStream; |
| import java.io.IOException; |
| import java.io.InputStream; |
| 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 user to specify an absolute or relative path in the plugin declaration. |
| * <p> |
| * The file is expected to contain Digester rules in xmlrules format. |
| * |
| * @since 1.6 |
| */ |
| public class FinderFromFile |
| extends RuleFinder |
| { |
| |
| /** |
| * The default XML attribute that needs to be present on a plugin declaration in order to specify the file to |
| * load rules from. |
| */ |
| private static final String DFLT_FILENAME_ATTR = "file"; |
| |
| /** See {@link #findLoader}. */ |
| private final String filenameAttr; |
| |
| /** See {@link #findLoader}. */ |
| public FinderFromFile() |
| { |
| this( DFLT_FILENAME_ATTR ); |
| } |
| |
| /** |
| * See {@link #findLoader}. |
| * |
| * @param filenameAttr the XML attribute that needs to be present on a plugin declaration in order to specify the |
| * file to load rules from. |
| */ |
| public FinderFromFile( String filenameAttr ) |
| { |
| this.filenameAttr = filenameAttr; |
| } |
| |
| /** |
| * If there exists a property with the name specified in the constructor, then load that file, run it through the |
| * xmlrules module and return an object encapsulating those rules. |
| * <p> |
| * If there is no matching property provided, then just return null. |
| * <p> |
| * The returned object (when non-null) will add the selected rules to the digester whenever its addRules method is |
| * invoked. |
| * |
| * @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( Digester d, Class<?> pluginClass, Properties p ) |
| throws PluginException |
| { |
| |
| String rulesFileName = p.getProperty( filenameAttr ); |
| if ( rulesFileName == null ) |
| { |
| // nope, user hasn't requested dynamic rules to be loaded |
| // from a specific file. |
| return null; |
| } |
| |
| InputStream is = null; |
| try |
| { |
| is = new FileInputStream( rulesFileName ); |
| } |
| catch ( IOException ioe ) |
| { |
| throw new PluginException( "Unable to process file [" + rulesFileName + "]", ioe ); |
| } |
| |
| try |
| { |
| RuleLoader loader = new LoaderFromStream( is ); |
| return loader; |
| } |
| catch ( Exception e ) |
| { |
| throw new PluginException( "Unable to load xmlrules from file [" + rulesFileName + "]", e ); |
| } |
| finally |
| { |
| try |
| { |
| is.close(); |
| } |
| catch ( IOException ioe ) |
| { |
| throw new PluginException( "Unable to close stream for file [" + rulesFileName + "]", ioe ); |
| } |
| } |
| } |
| |
| } |