001/* ======================================================================== 002 * JCommon : a free general purpose class library for the Java(tm) platform 003 * ======================================================================== 004 * 005 * (C) Copyright 2000-2005, by Object Refinery Limited and Contributors. 006 * 007 * Project Info: http://www.jfree.org/jcommon/index.html 008 * 009 * This library is free software; you can redistribute it and/or modify it 010 * under the terms of the GNU Lesser General Public License as published by 011 * the Free Software Foundation; either version 2.1 of the License, or 012 * (at your option) any later version. 013 * 014 * This library is distributed in the hope that it will be useful, but 015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public 017 * License for more details. 018 * 019 * You should have received a copy of the GNU Lesser General Public 020 * License along with this library; if not, write to the Free Software 021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 022 * USA. 023 * 024 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 025 * in the United States and other countries.] 026 * 027 * ------------ 028 * FrontendDefaultHandler.java 029 * ------------ 030 * (C) Copyright 2002-2005, by Object Refinery Limited. 031 * 032 * Original Author: David Gilbert (for Object Refinery Limited); 033 * Contributor(s): -; 034 * 035 * $Id: FrontendDefaultHandler.java,v 1.9 2008/09/10 09:20:49 mungady Exp $ 036 * 037 * Changes 038 * ------- 039 * 02-Feb-2005 : Initial version. 040 * 041 */ 042package org.jfree.xml; 043 044import java.net.MalformedURLException; 045import java.net.URL; 046import java.util.Iterator; 047import java.util.Enumeration; 048 049import org.jfree.util.Configuration; 050import org.jfree.util.DefaultConfiguration; 051import org.xml.sax.Locator; 052import org.xml.sax.SAXException; 053import org.xml.sax.helpers.DefaultHandler; 054 055/** 056 * The frontenddefault handler connects the SAX-backend with the handler implementations. 057 * It must be the base class for all parser implementations used by the ParserFrontEnd. 058 * 059 * @author Thomas Morgner 060 */ 061public abstract class FrontendDefaultHandler extends DefaultHandler implements Configuration { 062 /** 063 * A key for the content base. 064 */ 065 public static final String CONTENTBASE_KEY = "content-base"; 066 067 /** 068 * Storage for the parser configuration. 069 */ 070 private DefaultConfiguration parserConfiguration; 071 072 /** 073 * The DocumentLocator can be used to resolve the current parse position. 074 */ 075 private Locator locator; 076 077 /** 078 * The current comment handler used to receive xml comments. 079 */ 080 private final CommentHandler commentHandler; 081 082 /** 083 * Default constructor. 084 */ 085 protected FrontendDefaultHandler() { 086 this.parserConfiguration = new DefaultConfiguration(); 087 this.commentHandler = new CommentHandler(); 088 } 089 090 /** 091 * Returns the comment handler that is used to collect comments. 092 * 093 * @return the comment handler. 094 */ 095 public CommentHandler getCommentHandler() { 096 return this.commentHandler; 097 } 098 099 /** 100 * Receive an object for locating the origin of SAX document events. 101 * <p> 102 * The locator allows the application to determine the end position of 103 * any document-related event, even if the parser is not reporting an 104 * error. Typically, the application will use this information for 105 * reporting its own errors (such as character content that does not 106 * match an application's business rules). The information returned by 107 * the locator is probably not sufficient for use with a search engine. 108 * </p> 109 * 110 * @param locator the locator. 111 */ 112 public void setDocumentLocator(final Locator locator) { 113 this.locator = locator; 114 } 115 116 /** 117 * Returns the current locator. 118 * 119 * @return the locator. 120 */ 121 public Locator getLocator() { 122 return this.locator; 123 } 124 125 /** 126 * Returns the configuration property with the specified key. 127 * 128 * @param key the property key. 129 * @return the property value. 130 */ 131 public String getConfigProperty(final String key) { 132 return getConfigProperty(key, null); 133 } 134 135 /** 136 * Returns the configuration property with the specified key (or the specified default value 137 * if there is no such property). 138 * <p> 139 * If the property is not defined in this configuration, the code will lookup the property in 140 * the parent configuration.</p> 141 * 142 * @param key the property key. 143 * @param defaultValue the default value. 144 * @return the property value. 145 */ 146 public String getConfigProperty(final String key, final String defaultValue) { 147 return this.parserConfiguration.getConfigProperty(key, defaultValue); 148 } 149 150 /** 151 * Sets a parser configuration value. 152 * 153 * @param key the key. 154 * @param value the value. 155 */ 156 public void setConfigProperty(final String key, final String value) { 157 if (value == null) { 158 this.parserConfiguration.remove(key); 159 } 160 else { 161 this.parserConfiguration.setProperty(key, value); 162 } 163 } 164 165 /** 166 * Returns the configuration properties. 167 * 168 * @return An enumeration of the configuration properties. 169 */ 170 public Enumeration getConfigProperties() 171 { 172 return this.parserConfiguration.getConfigProperties(); 173 } 174 175 /** 176 * Returns a new instance of the parser. 177 * 178 * @return a new instance of the parser. 179 */ 180 public abstract FrontendDefaultHandler newInstance(); 181 182 /** 183 * Returns all keys with the given prefix. 184 * 185 * @param prefix the prefix 186 * @return the iterator containing all keys with that prefix 187 */ 188 public Iterator findPropertyKeys(final String prefix) { 189 return this.parserConfiguration.findPropertyKeys(prefix); 190 } 191 192 /** 193 * Returns the parse result. This method is called at the end of the 194 * parsing process and expects the generated object. 195 * 196 * @return the object. 197 * @throws SAXException if something went wrong. 198 */ 199 public abstract Object getResult() throws SAXException; 200 201 /** 202 * Gets the ContentBase used to resolve relative URLs. 203 * 204 * @return the current contentbase, or null if no contentBase is set. 205 */ 206 public URL getContentBase() { 207 final String contentBase = getConfigProperty(Parser.CONTENTBASE_KEY); 208 if (contentBase == null) { 209 return null; 210 } 211 try { 212 return new URL(contentBase); 213 } 214 catch (MalformedURLException mfe) { 215 throw new IllegalStateException("Content Base is illegal." + contentBase); 216 } 217 } 218 219 /** 220 * Returns a clone of this instance. 221 * 222 * @return A clone. 223 * 224 * @throws CloneNotSupportedException if there is a problem cloning. 225 */ 226 public Object clone () throws CloneNotSupportedException 227 { 228 final FrontendDefaultHandler o = (FrontendDefaultHandler) super.clone(); 229 o.parserConfiguration = (DefaultConfiguration) this.parserConfiguration.clone(); 230 return o; 231 } 232}