/*
* Copyright 1999-2004 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.chain.config;
import java.net.URL;
import org.apache.commons.chain.Catalog;
import org.apache.commons.digester.Digester;
import org.apache.commons.digester.RuleSet;
import org.xml.sax.InputSource;
/**
* <p>Class to parse the contents of an XML configuration file (using
* Commons Digester) that defines and configures commands and command chains
* to be registered in a {@link Catalog}. Advanced users can configure the
* detailed parsing behavior by configuring the properties of an instance
* of this class prior to calling the <code>parse()</code> method. It
* is legal to call the <code>parse()</code> method more than once, in order
* to parse more than one configuration document.</p>
*
* @author Craig R. McClanahan
* @version $Revision: 1.4 $ $Date: 2004/10/18 01:07:41 $
*/
public class ConfigParser {
// ----------------------------------------------------- Instance Variables
/**
* <p>The <code>Digester</code> to be used for parsing.</p>
*/
private Digester digester = null;
/**
* <p>The <code>RuleSet</code> to be used for configuring our Digester
* parsing rules.</p>
*/
private RuleSet ruleSet = null;
/**
* <p>Should Digester use the context class loader?
*/
private boolean useContextClassLoader = true;
// ------------------------------------------------------------- Properties
/**
* <p>Return the <code>Digester</code> instance to be used for
* parsing, creating one if necessary.</p>
*/
public Digester getDigester() {
if (digester == null) {
digester = new Digester();
RuleSet ruleSet = getRuleSet();
digester.setNamespaceAware(ruleSet.getNamespaceURI() != null);
digester.setUseContextClassLoader(getUseContextClassLoader());
digester.setValidating(false);
digester.addRuleSet(ruleSet);
}
return (digester);
}
/**
* <p>Return the <code>RuleSet</code> to be used for configuring
* our <code>Digester</code> parsing rules, creating one if necessary.</p>
*/
public RuleSet getRuleSet() {
if (ruleSet == null) {
ruleSet = new ConfigRuleSet();
}
return (ruleSet);
}
/**
* <p>Set the <code>RuleSet</code> to be used for configuring
* our <code>Digester</code> parsing rules.</p>
*
* @param ruleSet The new RuleSet to use
*/
public void setRuleSet(RuleSet ruleSet) {
this.digester = null;
this.ruleSet = ruleSet;
}
/**
* <p>Return the "use context class loader" flag. If set to
* <code>true</code>, Digester will attempt to instantiate new
* command and chain instances from the context class loader.</p>
*/
public boolean getUseContextClassLoader() {
return (this.useContextClassLoader);
}
/**
* <p>Set the "use context class loader" flag.</p>
*
* @param useContextClassLoader The new flag value
*/
public void setUseContextClassLoader(boolean useContextClassLoader) {
this.useContextClassLoader = useContextClassLoader;
}
// --------------------------------------------------------- Public Methods
/**
* <p>Parse the XML document at the specified URL, using the configured
* <code>RuleSet</code>, registering top level commands into the specified
* {@link Catalog}. Use this method <strong>only</strong> if you have
* <strong>NOT</strong> included any <code>factory</code> element in your
* configuration resource, and wish to supply the catalog explictly.</p>
*
* @param catalog {@link Catalog} into which configured chains are
* to be registered
* @param url <code>URL</code> of the XML document to be parsed
*
* @exception Exception if a parsing error occurs
*
* @deprecated Use parse(URL) on a configuration resource with "factory"
* element(s) embedded
*/
public void parse(Catalog catalog, URL url) throws Exception {
// Prepare our Digester instance
Digester digester = getDigester();
digester.clear();
digester.push(catalog);
// Prepare our InputSource
InputSource source = new InputSource(url.toExternalForm());
source.setByteStream(url.openStream());
// Parse the configuration document
digester.parse(source);
}
/**
* <p>Parse the XML document at the specified URL using the configured
* <code>RuleSet</code>, registering catalogs with nested chains and
* commands as they are encountered. Use this method <strong>only</strong>
* if you have included one or more <code>factory</code> elements in your
* configuration resource.</p>
*
* @param url <code>URL</code> of the XML document to be parsed
*
* @exception Exception if a parsing error occurs
*/
public void parse(URL url) throws Exception {
// Prepare our Digester instance
Digester digester = getDigester();
digester.clear();
// Prepare our InputSource
InputSource source = new InputSource(url.toExternalForm());
source.setByteStream(url.openStream());
// Parse the configuration document
digester.parse(source);
}
}