1 | /*
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2 | * XMLConverter.java
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3 | * Copyright (C) 2002 New Zealand Digital Library, http://www.nzdl.org
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4 | *
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5 | * This program is free software; you can redistribute it and/or modify
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6 | * it under the terms of the GNU General Public License as published by
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7 | * the Free Software Foundation; either version 2 of the License, or
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8 | * (at your option) any later version.
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9 | *
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10 | * This program is distributed in the hope that it will be useful,
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11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 | * GNU General Public License for more details.
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14 | *
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15 | * You should have received a copy of the GNU General Public License
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16 | * along with this program; if not, write to the Free Software
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17 | * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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18 | */
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19 | package org.greenstone.gsdl3.util;
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20 |
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21 | // XML classes
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22 | import org.w3c.dom.DOMImplementation;
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23 | import org.w3c.dom.Document;
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24 | import org.w3c.dom.DocumentType;
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25 | import org.w3c.dom.Element;
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26 | import org.w3c.dom.Node;
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27 | import org.w3c.dom.NodeList;
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28 | import org.w3c.dom.NamedNodeMap;
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29 | import org.xml.sax.InputSource;
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30 | import org.xml.sax.EntityResolver;
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31 | import org.xml.sax.ErrorHandler;
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32 | import org.xml.sax.SAXParseException;
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33 | import org.apache.xerces.parsers.DOMParser;
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34 | import org.apache.xerces.dom.*; // for new Documents
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35 |
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36 | // other java classes
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37 | import java.io.Reader;
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38 | import java.io.InputStreamReader;
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39 | import java.io.StringReader;
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40 | import java.io.File;
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41 | import java.io.FileInputStream;
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42 | import java.io.FileReader;
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43 |
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44 | import org.apache.log4j.*;
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45 |
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46 | /** XMLConverter - utility class for greenstone
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47 | *
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48 | * parses XML Strings into Documents, converts Nodes to Strings
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49 | * different parsers have different behaviour - can experiment in here
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50 | * now we only use xerces
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51 | *
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52 | */
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53 | public class XMLConverter {
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54 |
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55 | static Logger logger = Logger.getLogger(org.greenstone.gsdl3.util.XMLConverter.class.getName());
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56 |
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57 | /** xerces parser */
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58 | protected DOMParser parser = null;
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59 |
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60 | private static boolean outputEscaping = true;
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61 |
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62 |
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63 | /** the no-args constructor */
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64 | public XMLConverter() {
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65 | try {
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66 | this.parser = new DOMParser();
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67 | this.parser.setFeature("http://xml.org/sax/features/validation", false);
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68 | // don't try and load external DTD - no need if we are not validating, and may cause connection errors if a proxy is not set up.
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69 | this.parser.setFeature("http://apache.org/xml/features/nonvalidating/load-external-dtd", false);
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70 | // a performance test showed that having this on lead to increased
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71 | // memory use for small-medium docs, and not much gain for large
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72 | // docs.
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73 | // http://www.sosnoski.com/opensrc/xmlbench/conclusions.html
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74 | this.parser.setFeature("http://apache.org/xml/features/dom/defer-node-expansion", false);
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75 | // add an errorhandler to the parser which will store useful a error message on encountering fatal errors, errors and warnings when parsing
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76 | // this errormessage can then be converted to xhtml and displayed in a browser.
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77 | this.parser.setErrorHandler(new ParseErrorHandler());
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78 | } catch (Exception e) {
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79 | logger.error(e.getMessage());
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80 | }
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81 | }
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82 |
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83 | /** sets the entity resolver. pass in null to unset it */
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84 | public void setEntityResolver(EntityResolver er) {
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85 | this.parser.setEntityResolver(er);
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86 | }
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87 |
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88 | /** Given a Node representing an Element or Document, will return the
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89 | * Element/docroot Element. Returns null if the Node was not an element. */
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90 | public static Element nodeToElement(Node node)
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91 | {
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92 | if(node == null) {
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93 | return null;
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94 | }
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95 | short nodeType = node.getNodeType();
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96 |
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97 | if (nodeType == Node.DOCUMENT_NODE) {
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98 | Document docNode = (Document)node;
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99 | return docNode.getDocumentElement() ;
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100 | }
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101 | else if (nodeType == Node.ELEMENT_NODE) {
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102 | return (Element)node;
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103 | }
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104 | else {
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105 | String message = "Expecting Document or Element node type but got "
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106 | + node.getNodeName() + "\nReturning null";
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107 | System.err.println(message);
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108 | logger.warn(message);
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109 | return null;
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110 | }
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111 | }
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112 |
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113 | /** returns a DOM Document */
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114 | public Document getDOM(String in) {
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115 |
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116 | try {
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117 | Reader reader = new StringReader(in);
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118 | InputSource xml_source = new InputSource(reader);
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119 |
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120 | this.parser.parse(xml_source);
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121 | Document doc = this.parser.getDocument();
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122 |
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123 | return doc;
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124 |
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125 | } catch (Exception e) {
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126 | logger.error(e.getMessage());
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127 | }
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128 | return null;
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129 | }
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130 |
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131 | /** returns a DOM Document */
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132 | public Document getDOM(File in) {
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133 | try {
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134 | FileReader reader = new FileReader(in);
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135 | InputSource xml_source = new InputSource(reader);
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136 | this.parser.parse(xml_source);
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137 | Document doc = this.parser.getDocument();
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138 | return doc;
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139 |
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140 | } catch (Exception e) {
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141 | logger.error(e.getMessage(), e);
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142 |
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143 | }
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144 | return null;
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145 | }
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146 |
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147 | /** returns a DOM document */
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148 | public Document getDOM(File in, String encoding) {
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149 | try {
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150 |
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151 | InputStreamReader isr = new InputStreamReader(new FileInputStream(in), encoding);
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152 | InputSource xml_source = new InputSource(isr);
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153 |
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154 | this.parser.parse(xml_source);
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155 | Document doc = this.parser.getDocument();
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156 |
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157 | return doc;
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158 |
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159 | } catch (Exception e) {
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160 | logger.error(e.getMessage());
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161 | }
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162 | return null;
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163 | }
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164 |
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165 |
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166 | /** creates a new empty DOM Document */
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167 | public static Document newDOM() {
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168 | Document doc = new DocumentImpl();
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169 | return doc;
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170 | }
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171 |
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172 | /**
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173 | * This method's parameters represent the parts of the Doctype of this
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174 | * Document that is to be created.
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175 | * For more info see
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176 | * http://xerces.apache.org/xerces-j/apiDocs/org/apache/xerces/dom/DocumentTypeImpl.html#DocumentTypeImpl(org.apache.xerces.dom.CoreDocumentImpl,%20java.lang.String)
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177 | *
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178 | * */
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179 | public static Document newDOM(String qualifiedName, String publicID, String systemID) {
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180 | // create empty DOM document
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181 | DocumentImpl docImpl = new DocumentImpl();
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182 |
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183 | // Need to use the document to create the docType for it
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184 | DocumentType myDocType = new DocumentTypeImpl(docImpl, qualifiedName, publicID, systemID);
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185 |
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186 | // Although we have created the docType using the document, we need to still
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187 | // put it into the empty document we just created
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188 | try{
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189 | docImpl.appendChild(myDocType);
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190 | } catch(Exception e) {
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191 | System.out.println("Could not append docType because: " + e) ;
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192 | }
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193 |
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194 | // return the document containing a DocType
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195 | return docImpl;
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196 | }
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197 |
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198 | /** returns the Node as a String */
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199 | public static String getString(Node xmlNode)
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200 | {
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201 | outputEscaping = true;
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202 | StringBuffer xmlRepresentation = new StringBuffer();
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203 | getString(xmlNode, xmlRepresentation, 0, false);
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204 | return xmlRepresentation.toString();
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205 | }
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206 |
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207 | /** returns the node as a nicely formatted String - this introduces extra
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208 | * text nodes if the String is read back in as a DOM, so should only be
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209 | * used for printing */
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210 | public static String getPrettyString(Node xmlNode) {
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211 |
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212 | outputEscaping = true;
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213 | StringBuffer xmlRepresentation = new StringBuffer();
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214 | getString(xmlNode, xmlRepresentation, 0, true);
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215 | return xmlRepresentation.toString();
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216 | }
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217 |
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218 | private static void getString(Node xmlNode, StringBuffer xmlRepresentation,
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219 | int depth, boolean pretty)
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220 | {
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221 |
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222 | if (xmlNode == null) {
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223 | xmlRepresentation.append("<null>");
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224 | return;
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225 | }
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226 |
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227 | short nodeType = xmlNode.getNodeType();
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228 | String nodeName = xmlNode.getNodeName();
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229 |
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230 | if (nodeType == Node.DOCUMENT_NODE) {
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231 | Document xmlDocNode = (Document)xmlNode;
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232 |
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233 | //if (xmlDocNode.getDoctype() == null) {
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234 | //System.err.println("Doctype is null.");
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235 | //}
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236 | //else {
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237 | if (xmlDocNode.getDoctype() != null) {
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238 | DocumentType dt = xmlDocNode.getDoctype();
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239 |
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240 | String name = dt.getName();
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241 | String pid = dt.getPublicId();
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242 | String sid = dt.getSystemId();
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243 |
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244 | String doctype_str = "<!DOCTYPE " + dt.getName() + " PUBLIC \"" + pid + "\" \"" + sid + "\">\n";
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245 |
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246 | xmlRepresentation.append(doctype_str);
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247 | }
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248 | getString(xmlDocNode.getDocumentElement(), xmlRepresentation, depth, pretty);
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249 | return;
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250 | }
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251 | // Handle Element nodes
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252 | if (nodeType == Node.ELEMENT_NODE) {
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253 | if (pretty) {
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254 | xmlRepresentation.append("\n");
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255 | for (int i = 0; i < depth; i++) {
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256 | xmlRepresentation.append(" ");
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257 | }
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258 | }
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259 |
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260 | // Write opening tag
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261 | xmlRepresentation.append("<");
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262 | xmlRepresentation.append(nodeName);
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263 |
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264 | // Write the node attributes
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265 | NamedNodeMap nodeAttributes = xmlNode.getAttributes();
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266 | for (int i = 0; i < nodeAttributes.getLength(); i++) {
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267 | Node attribute = nodeAttributes.item(i);
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268 | xmlRepresentation.append(" ");
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269 | xmlRepresentation.append(attribute.getNodeName());
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270 | xmlRepresentation.append("=\"");
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271 | xmlRepresentation.append(attribute.getNodeValue());
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272 | xmlRepresentation.append("\"");
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273 | }
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274 |
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275 | // If the node has no children, close the opening tag and return
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276 | if (xmlNode.hasChildNodes() == false) {
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277 | // This produces somewhat ugly output, but it is necessary to compensate
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278 | // for display bugs in Netscape. Firstly, the space is needed before the
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279 | // closing bracket otherwise Netscape will ignore some tags (<br/>, for
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280 | // example). Also, a newline character would be expected after the tag,
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281 | // but this causes problems with the display of links (the link text
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282 | // will contain a newline character, which is displayed badly).
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283 | xmlRepresentation.append(" />");
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284 | return;
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285 | }
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286 |
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287 | // Close the opening tag
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288 | xmlRepresentation.append(">");
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289 |
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290 | // Apply recursively to the children of this node
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291 | // hack for nodes next to text nodes - dont make them pretty
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292 | // this is needed for text inside a <pre> element - any new lines
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293 | // or spaces around the span elements show up in the text
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294 | NodeList children = xmlNode.getChildNodes();
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295 | boolean do_pretty = pretty;
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296 | for (int i = 0; i < children.getLength(); i++) {
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297 | if (children.item(i).getNodeType()==Node.TEXT_NODE) {
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298 | do_pretty=false; // if there is a text node amongst the children, do teh following nodes in non-pretty mode - hope this doesn't stuff up something else
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299 | }
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300 | getString(children.item(i), xmlRepresentation, depth + 1, do_pretty);
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301 | }
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302 |
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303 | // Write closing tag
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304 | if (pretty) {
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305 | if (xmlRepresentation.charAt(xmlRepresentation.length()-1) == '\n') {
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306 | for (int i = 0; i < depth; i++)
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307 | xmlRepresentation.append(" ");
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308 | }
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309 | }
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310 | xmlRepresentation.append("</");
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311 | xmlRepresentation.append(nodeName);
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312 | xmlRepresentation.append(">");
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313 | if (pretty) {
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314 | xmlRepresentation.append("\n");
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315 | }
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316 | }
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317 |
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318 | // Handle Text nodes
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319 | else if (nodeType == Node.TEXT_NODE) {
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320 | String text = xmlNode.getNodeValue();
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321 |
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322 | // Perform output escaping, if required
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323 | if (outputEscaping) {
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324 | text = text.replaceAll("&", "&"); // Must be done first!!
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325 | text = text.replaceAll("<", "<");
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326 | text = text.replaceAll(">", ">");
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327 | text = text.replaceAll("\"", """);
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328 | text = text.replaceAll("\'", "'");
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329 | }
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330 |
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331 | // Remove any control-C characters
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332 | text = text.replaceAll("" + (char) 3, "");
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333 | xmlRepresentation.append(text);
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334 | }
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335 |
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336 | // Handle Processing Instruction nodes
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337 | else if (nodeType == Node.PROCESSING_INSTRUCTION_NODE) {
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338 | if (nodeName.equals("javax.xml.transform.disable-output-escaping")) {
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339 | outputEscaping = false;
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340 | }
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341 | else if (nodeName.equals("javax.xml.transform.enable-output-escaping")) {
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342 | outputEscaping = true;
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343 | }
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344 | else {
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345 | logger.warn("Unhandled processing instruction " + nodeName);
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346 | }
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347 | }
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348 |
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349 | else if (nodeType == Node.COMMENT_NODE) {
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350 | String text = xmlNode.getNodeValue();
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351 | xmlRepresentation.append("<!-- ");
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352 | xmlRepresentation.append(text);
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353 | xmlRepresentation.append(" -->");
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354 | }
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355 |
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356 |
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357 |
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358 | // A type of node that is not handled yet
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359 | else {
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360 | logger.warn("Unknown node type: " + nodeType+" "+getNodeTypeString(nodeType));
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361 | }
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362 |
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363 | return;
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364 | }
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365 |
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366 | protected static String getNodeTypeString(short node_type) {
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367 |
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368 | String type = "";
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369 | switch(node_type) {
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370 | case Node.ATTRIBUTE_NODE:
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371 | type="ATTRIBUTE_NODE";
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372 | break;
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373 | case Node.CDATA_SECTION_NODE:
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374 | type="CDATA_SECTION_NODE";
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375 | break;
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376 | case Node.COMMENT_NODE:
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377 | type="COMMENT_NODE";
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378 | break;
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379 | case Node.DOCUMENT_FRAGMENT_NODE:
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380 | type="DOCUMENT_FRAGMENT_NODE";
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381 | break;
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382 | case Node.DOCUMENT_NODE:
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383 | type="DOCUMENT_NODE";
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384 | break;
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385 | case Node.DOCUMENT_TYPE_NODE:
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386 | type="DOCUMENT_TYPE_NODE";
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387 | break;
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388 | case Node.ELEMENT_NODE:
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389 | type="ELEMENT_NODE";
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390 | break;
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391 | case Node.ENTITY_NODE:
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392 | type="ENTITY_NODE";
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393 | break;
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394 | case Node.ENTITY_REFERENCE_NODE:
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395 | type="ENTITY_REFERENCE_NODE";
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396 | break;
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397 | case Node.NOTATION_NODE:
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398 | type="NOTATION_NODE";
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399 | break;
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400 | case Node.PROCESSING_INSTRUCTION_NODE:
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401 | type="PROCESSING_INSTRUCTION_NODE";
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402 | break;
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403 | case Node.TEXT_NODE:
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404 | type="TEXT_NODE";
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405 | break;
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406 | default:
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407 | type="UNKNOWN";
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408 | }
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409 |
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410 | return type;
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411 | }
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412 |
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413 | // returns null if there no error occurred during parsing, or else returns the error message
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414 | public String getParseErrorMessage() {
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415 | ParseErrorHandler errorHandler = (ParseErrorHandler)this.parser.getErrorHandler();
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416 | return errorHandler.getErrorMessage();
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417 | }
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418 |
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419 | // Errorhandler for SAXParseExceptions that are errors, fatal errors or warnings. This class can be used to
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420 | // register a handler for any fatal errors, errors and warnings that may occur when parsing an xml file. The
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421 | // errors are printed both to the greenstone.log and to the tomcat console (System.err), and the error message
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422 | // is stored in the errorMessage variable so that it can be retrieved and be used to generate an xhtml error page.
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423 | static public class ParseErrorHandler implements ErrorHandler {
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424 | protected String errorMessage = null;
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425 |
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426 | // Receive notification of a recoverable error.
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427 | public void error(SAXParseException exception) {
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428 | handleError("Error:\n", exception);
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429 | }
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430 | // Receive notification of a non-recoverable error.
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431 | public void fatalError(SAXParseException exception) {
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432 | handleError("Fatal Error:\n", exception);
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433 | }
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434 | // Receive notification of a warning.
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435 | public void warning(SAXParseException exception) {
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436 | handleError("Warning:\n", exception);
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437 | }
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438 |
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439 | public String toString(SAXParseException e) {
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440 | String msg = e.getMessage();
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441 | msg += "\nOn line(column): " + e.getLineNumber() + "(" + e.getColumnNumber() + ")";
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442 | msg += (e.getPublicId() != null) ? ("\npublic ID: " + e.getPublicId()) : "\nNo public ID";
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443 | msg += (e.getSystemId() != null) ? ("\nsystem ID: " + e.getSystemId()) : "\nNo system ID";
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444 |
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445 | return msg;
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446 | }
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447 |
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448 | // clears the errorPage variable after first call to this method
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449 | public String getErrorMessage() {
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450 | String errMsg = this.errorMessage;
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451 | if(this.errorMessage != null) {
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452 | this.errorMessage = null;
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453 | }
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454 | return errMsg;
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455 | }
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456 |
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457 | // sets the errorMessage member variable to the data stored in the exception
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458 | // and writes the errorMessage to the logger and tomcat's System.err
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459 | protected void handleError(String errorType, SAXParseException exception) {
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460 | this.errorMessage = errorType + toString(exception);
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461 | System.err.println("\n****Error parsing xml:\n" + this.errorMessage + "\n****\n");
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462 | logger.error(this.errorMessage);
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463 | }
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464 | }
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465 | }
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