org.apache.commons.digester.plugins.strategies.FinderFromFile Maven / Gradle / Ivy
/* $Id: FinderFromFile.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 java.io.InputStream;
import java.io.FileInputStream;
import java.io.IOException;
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 user to specify an absolute
* or relative path in the plugin declaration.
*
* The file is expected to contain Digester rules in xmlrules format.
*
* @since 1.6
*/
public class FinderFromFile extends RuleFinder {
/**
* Xml attribute that needs to be present on a plugin declaration
* in order to specify the file to load rules from.
*/
public static String DFLT_FILENAME_ATTR = "file";
/** See {@link #findLoader}. */
private String filenameAttr;
/** See {@link #findLoader}. */
public FinderFromFile() {
this(DFLT_FILENAME_ATTR);
}
/** See {@link #findLoader}. */
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.
*
* If there is no matching property provided, then just return null.
*
* The returned object (when non-null) will add the selected rules to
* the digester whenever its addRules method is invoked.
*/
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(java.io.IOException ioe) {
throw new PluginException(
"Unable to close stream for file [" +
rulesFileName + "]", ioe);
}
}
}
}