Java tutorial
/* $Id: DigesterLoader.java 992060 2010-09-02 19:09:47Z simonetripodi $ * * 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 org.apache.commons.digester.Digester; import org.apache.commons.digester.RuleSet; import org.osgi.framework.Bundle; import org.xml.sax.InputSource; import org.xml.sax.SAXException; import java.io.IOException; import java.io.InputStream; import java.io.Reader; import java.net.URL; /** * This class manages the creation of Digester instances from XML digester * rules files. * * @since 1.2 */ public class DigesterLoader { /** * Creates a new digester and initializes it from the specified InputSource * * @param rulesSource load the xml rules from this InputSource * @return a new Digester initialized with the rules */ public static Digester createDigester(InputSource rulesSource) { RuleSet ruleSet = new FromXmlRuleSet(rulesSource); Digester digester = new Digester(); digester.addRuleSet(ruleSet); return digester; } /** * Creates a new digester and initializes it from the specified InputSource. * This constructor allows the digester to be used to load the rules to be specified. * This allows properties to be configured on the Digester instance before it is used. * * @param rulesSource load the xml rules from this InputSource * @param rulesDigester digester to load the specified XML file. * @return a new Digester initialized with the rules */ public static Digester createDigester(InputSource rulesSource, Digester rulesDigester) { RuleSet ruleSet = new FromXmlRuleSet(rulesSource, rulesDigester); Digester digester = new Digester(); digester.addRuleSet(ruleSet); return digester; } /** * Creates a new digester and initializes it from the specified XML file * * @param rulesXml URL to the XML file defining the digester rules * @return a new Digester initialized with the rules */ public static Digester createDigester(URL rulesXml) { RuleSet ruleSet = new FromXmlRuleSet(rulesXml); Digester digester = new Digester(); digester.addRuleSet(ruleSet); return digester; } public static Digester createDigester(Bundle bundle, URL rulesXml) { RuleSet ruleSet = new FromXmlRuleSet(rulesXml); Digester digester = new Digester(); digester.setClassloader(bundle); digester.addRuleSet(ruleSet); return digester; } /** * Creates a new digester and initializes it from the specified XML file. * This constructor allows specifing a rulesDigester to do the XML file * loading; thus no matter the XML files is packed into a jar, a war, or a * ear, the rulesDigester can always find the XML files with properly set * ClassLoader. * * @param rulesXml URL to the XML file defining the digester rules * @param rulesDigester digester to load the specified XML file. * @return a new Digester initialized with the rules */ public static Digester createDigester(URL rulesXml, Digester rulesDigester) { RuleSet ruleSet = new FromXmlRuleSet(rulesXml, rulesDigester); Digester digester = new Digester(); digester.addRuleSet(ruleSet); return digester; } /** * Given the digester rules XML file, a class loader, and an XML input file, * this method parses the input file into Java objects. The class loader * is used by the digester to create the Java objects. * * @param digesterRules URL to the XML document defining the digester rules * @param classLoader the ClassLoader to register with the digester * @param fileURL URL to the XML file to parse into Java objects * @return an Object which is the root of the network of Java objects * created by digesting fileURL */ public static Object load(URL digesterRules, Bundle classLoader, URL fileURL) throws IOException, SAXException, DigesterLoadingException { return load(digesterRules, classLoader, fileURL.openStream()); } /** * Given the digester rules XML file, a class loader, and an input stream, * this method parses the input into Java objects. The class loader * is used by the digester to create the Java objects. * * @param digesterRules URL to the XML document defining the digester rules * @param classLoader the ClassLoader to register with the digester * @param input InputStream over the XML file to parse into Java objects * @return an Object which is the root of the network of Java objects * created by digesting fileURL */ public static Object load(URL digesterRules, Bundle classLoader, InputStream input) throws IOException, SAXException, DigesterLoadingException { Digester digester = createDigester(digesterRules); digester.setClassloader(classLoader); try { return digester.parse(input); } catch (XmlLoadException ex) { // This is a runtime exception that can be thrown by // FromXmlRuleSet#addRuleInstances, which is called by the Digester // before it parses the file. throw new DigesterLoadingException(ex.getMessage(), ex); } } /** * Given the digester rules XML file, a class loader, and an input stream, * this method parses the input into Java objects. The class loader * is used by the digester to create the Java objects. * * @param digesterRules URL to the XML document defining the digester rules * @param classLoader the ClassLoader to register with the digester * @param reader Reader over the XML file to parse into Java objects * @return an Object which is the root of the network of Java objects * created by digesting fileURL */ public static Object load(URL digesterRules, Bundle classLoader, Reader reader) throws IOException, SAXException, DigesterLoadingException { Digester digester = createDigester(digesterRules); digester.setClassloader(classLoader); try { return digester.parse(reader); } catch (XmlLoadException ex) { // This is a runtime exception that can be thrown by // FromXmlRuleSet#addRuleInstances, which is called by the Digester // before it parses the file. throw new DigesterLoadingException(ex.getMessage(), ex); } } /** * Given the digester rules XML file, a class loader, and an XML input file, * this method parses the input file into Java objects. The class loader * is used by the digester to create the Java objects. * * @param digesterRules URL to the XML document defining the digester rules * @param classLoader the ClassLoader to register with the digester * @param fileURL URL to the XML file to parse into Java objects * @param rootObject an Object to push onto the digester's stack, prior * to parsing the input * @return an Object which is the root of the network of Java objects. * Usually, this will be the same object as rootObject * created by digesting fileURL */ public static Object load(URL digesterRules, Bundle classLoader, URL fileURL, Object rootObject) throws IOException, SAXException, DigesterLoadingException { return load(digesterRules, classLoader, fileURL.openStream(), rootObject); } /** * Given the digester rules XML file, a class loader, and an input stream, * this method parses the input into Java objects. The class loader * is used by the digester to create the Java objects. * * @param digesterRules URL to the XML document defining the digester rules * @param bundle the ClassLoader to register with the digester * @param input InputStream over the XML file to parse into Java objects * @param rootObject an Object to push onto the digester's stack, prior * to parsing the input * @return an Object which is the root of the network of Java objects * created by digesting fileURL */ public static Object load(URL digesterRules, Bundle bundle, InputStream input, Object rootObject) throws IOException, SAXException, DigesterLoadingException { Digester digester = createDigester(digesterRules); digester.setClassloader(bundle); digester.push(rootObject); try { return digester.parse(input); } catch (XmlLoadException ex) { // This is a runtime exception that can be thrown by // FromXmlRuleSet#addRuleInstances, which is called by the Digester // before it parses the file. throw new DigesterLoadingException(ex.getMessage(), ex); } } /** * Given the digester rules XML file, a class loader, and an input stream, * this method parses the input into Java objects. The class loader * is used by the digester to create the Java objects. * * @param digesterRules URL to the XML document defining the digester rules * @param classLoader the ClassLoader to register with the digester * @param input Reader over the XML file to parse into Java objects * @param rootObject an Object to push onto the digester's stack, prior * to parsing the input * @return an Object which is the root of the network of Java objects * created by digesting fileURL */ public static Object load(URL digesterRules, Bundle classLoader, Reader input, Object rootObject) throws IOException, SAXException, DigesterLoadingException { Digester digester = createDigester(digesterRules); digester.setClassloader(classLoader); digester.push(rootObject); try { return digester.parse(input); } catch (XmlLoadException ex) { // This is a runtime exception that can be thrown by // FromXmlRuleSet#addRuleInstances, which is called by the Digester // before it parses the file. throw new DigesterLoadingException(ex.getMessage(), ex); } } }