org.apache.commons.digester.xmlrules.FromXmlRuleSet Maven / Gradle / Ivy
/* $Id: FromXmlRuleSet.java 471661 2006-11-06 08:09:25Z skitching $
*
* 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.xmlrules;
import java.net.URL;
import org.apache.commons.digester.Digester;
import org.apache.commons.digester.RuleSetBase;
import org.xml.sax.InputSource;
/**
* A Digester rule set where the rules come from an XML file.
*
* @since 1.2
*/
public class FromXmlRuleSet extends RuleSetBase {
public static final String DIGESTER_DTD_PATH = "org/apache/commons/digester/xmlrules/digester-rules.dtd";
/**
* The file containing the Digester rules, in XML.
*/
private XMLRulesLoader rulesLoader;
/**
* The rule set for parsing the Digester rules
*/
private DigesterRuleParser parser;
/**
* The digester for loading the rules xml.
*/
private Digester rulesDigester;
/**
* Constructs a FromXmlRuleSet using the default DigesterRuleParser and
* rulesDigester.
* @param rulesXml the path to the XML document defining the Digester rules
*/
public FromXmlRuleSet(URL rulesXml) {
this(rulesXml, new DigesterRuleParser(), new Digester());
}
/**
* Constructs a FromXmlRuleSet using the default DigesterRuleParser and
* a ruleDigester for loading the rules xml.
* @param rulesXml the path to the XML document defining the Digester rules
* @param rulesDigester the digester to read the rules xml.
*/
public FromXmlRuleSet(URL rulesXml, Digester rulesDigester) {
this(rulesXml, new DigesterRuleParser(), rulesDigester);
}
/**
* @param rulesXml the path to the XML document defining the Digester rules
* @param parser an instance of DigesterRuleParser, for parsing the rules from XML
*/
public FromXmlRuleSet(URL rulesXml, DigesterRuleParser parser) {
this(rulesXml, parser, new Digester());
}
/**
* @param rulesXml the path to the XML document defining the Digester rules
* @param parser an instance of DigesterRuleParser, for parsing the rules from XML
* @param rulesDigester the digester used to load the Xml rules.
*/
public FromXmlRuleSet(URL rulesXml, DigesterRuleParser parser, Digester rulesDigester) {
init(new URLXMLRulesLoader(rulesXml), parser, rulesDigester);
}
/**
* Constructs a FromXmlRuleSet using the default DigesterRuleParser and
* rulesDigester.
* @param inputSource load the xml rules from this InputSource
*/
public FromXmlRuleSet(InputSource inputSource) {
this(inputSource, new DigesterRuleParser(), new Digester());
}
/**
* Constructs a FromXmlRuleSet using the default DigesterRuleParser and
* a ruleDigester for loading the rules xml.
* @param inputSource load the xml rules from this InputSource
* @param rulesDigester the digester to read the rules xml.
*/
public FromXmlRuleSet(InputSource inputSource, Digester rulesDigester) {
this(inputSource, new DigesterRuleParser(), rulesDigester);
}
/**
* @param inputSource load the xml rules from this InputSource
* @param parser an instance of DigesterRuleParser, for parsing the rules from XML
*/
public FromXmlRuleSet(InputSource inputSource, DigesterRuleParser parser) {
this(inputSource, parser, new Digester());
}
/**
* @param inputSource load the xml rules from this InputSource
* @param parser an instance of DigesterRuleParser, for parsing the rules from XML
* @param rulesDigester the digester used to load the Xml rules.
*/
public FromXmlRuleSet(InputSource inputSource, DigesterRuleParser parser, Digester rulesDigester) {
init(new InputSourceXMLRulesLoader(inputSource), parser, rulesDigester);
}
/**
* Base constructor
*/
private void init(XMLRulesLoader rulesLoader, DigesterRuleParser parser, Digester rulesDigester) {
this.rulesLoader = rulesLoader;
this.parser = parser;
this.rulesDigester = rulesDigester;
}
/**
* Adds to the digester the set of Rule instances defined in the
* XML file for this rule set.
* @see org.apache.commons.digester.RuleSetBase
*/
public void addRuleInstances(org.apache.commons.digester.Digester digester) throws XmlLoadException {
addRuleInstances(digester, null);
}
/**
* Adds to the digester the set of Rule instances defined in the
* XML file for this rule set.
*
* Note that this method doesn't have a matching one on the DigesterLoader
* class, because it is not expected to be widely used, and DigesterLoader's
* load method is already heavily overloaded.
*
* @param digester is the digester that rules will be added to.
* @param basePath is a path that will be prefixed to every
* pattern string defined in the xmlrules input file.
*
* @see org.apache.commons.digester.RuleSetBase
* @since 1.6
*/
public void addRuleInstances(
org.apache.commons.digester.Digester digester,
String basePath)
throws XmlLoadException {
URL dtdURL = getClass().getClassLoader().getResource(DIGESTER_DTD_PATH);
if (dtdURL == null) {
throw new XmlLoadException("Cannot find resource \"" +
DIGESTER_DTD_PATH + "\"");
}
parser.setDigesterRulesDTD(dtdURL.toString());
parser.setTarget(digester);
parser.setBasePath(basePath);
rulesDigester.addRuleSet(parser);
rulesDigester.push(parser);
rulesLoader.loadRules();
}
/**
* Worker class encapsulates loading mechanisms.
* Private until some reason is found to make it public.
*/
private abstract static class XMLRulesLoader {
/** Load rules now */
public abstract void loadRules() throws XmlLoadException;
}
/** Loads XMLRules from an URL */
private class URLXMLRulesLoader extends XMLRulesLoader {
private URL url;
public URLXMLRulesLoader(URL url) {
this.url = url;
}
public void loadRules() throws XmlLoadException {
try {
rulesDigester.parse(url.openStream());
} catch (Exception ex) {
throw new XmlLoadException(ex);
}
}
}
/** Loads XMLRules from an InputSource */
private class InputSourceXMLRulesLoader extends XMLRulesLoader {
private InputSource inputSource;
public InputSourceXMLRulesLoader(InputSource inputSource) {
this.inputSource = inputSource;
}
public void loadRules() throws XmlLoadException {
try {
rulesDigester.parse(inputSource);
} catch (Exception ex) {
throw new XmlLoadException(ex);
}
}
}
}