1 | /*
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2 | * XMLTransformer.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 javax.xml.transform.Transformer;
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23 | import javax.xml.transform.TransformerFactory;
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24 | import javax.xml.transform.TransformerConfigurationException;
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25 | import javax.xml.transform.TransformerException;
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26 | import javax.xml.transform.ErrorListener;
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27 |
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28 | import javax.xml.transform.stream.StreamSource;
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29 | import javax.xml.transform.dom.DOMSource;
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30 | import javax.xml.transform.stream.StreamResult;
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31 | import javax.xml.transform.dom.DOMResult;
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32 |
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33 | import javax.xml.parsers.DocumentBuilderFactory;
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34 | import javax.xml.parsers.DocumentBuilder;
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35 | import org.w3c.dom.Element;
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36 | import org.w3c.dom.Document;
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37 |
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38 | import org.w3c.dom.Node;
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39 | import org.w3c.dom.NodeList;
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40 |
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41 | // other java classes
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42 | import java.io.StringReader;
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43 | import java.io.StringWriter;
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44 | import java.io.File;
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45 | import java.util.HashMap;
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46 | import java.util.Set;
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47 | import java.util.Map;
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48 | import java.util.Iterator;
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49 |
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50 | import org.apache.xml.utils.DefaultErrorHandler;
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51 |
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52 | import org.apache.log4j.*;
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53 |
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54 | /** XMLTransformer - utility class for greenstone
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55 | *
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56 | * transforms xml using xslt
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57 | *
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58 | * @author <a href="mailto:[email protected]">Katherine Don</a>
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59 | * @version $Revision: 18452 $
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60 | */
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61 | public class XMLTransformer {
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62 |
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63 | static Logger logger = Logger.getLogger(org.greenstone.gsdl3.util.XMLTransformer.class.getName());
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64 |
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65 | /** The transformer factory we're using */
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66 | TransformerFactory t_factory=null;
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67 |
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68 | /**
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69 | * The no-arguments constructor.
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70 | *
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71 | * Any exceptions thrown are caught internally
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72 | *
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73 | * @see javax.xml.transform.TransformerFactory
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74 | */
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75 | public XMLTransformer() {
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76 |
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77 | // make sure we are using the xalan transformer
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78 | System.setProperty("javax.xml.transform.TransformerFactory", "org.apache.xalan.processor.TransformerFactoryImpl");
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79 | try {
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80 | this.t_factory = org.apache.xalan.processor.TransformerFactoryImpl.newInstance();
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81 |
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82 | } catch (Exception e) {
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83 | logger.error("exception "+e.getMessage());
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84 | }
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85 | }
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86 |
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87 |
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88 |
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89 | /**
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90 | * Transform an XML document using a XSLT stylesheet
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91 | *
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92 | * @param stylesheet a filename for an XSLT stylesheet
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93 | * @param xml_in the XML to be transformed
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94 | * @return the transformed XML
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95 | */
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96 | public String transform(String stylesheet, String xml_in) {
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97 |
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98 | try {
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99 | // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
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100 | Transformer transformer = this.t_factory.newTransformer(new StreamSource(stylesheet));
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101 | transformer.setErrorListener(new TransformErrorListener());
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102 |
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103 | // Use the Transformer to transform an XML Source and send the output to a Result object.
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104 | StringWriter output = new StringWriter();
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105 |
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106 | transformer.transform(new StreamSource(new StringReader(xml_in)), new StreamResult(output));
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107 | return output.toString();
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108 | } catch (TransformerConfigurationException e) {
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109 | logger.error("couldn't create transformer object: "+e.getMessageAndLocation());
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110 | logger.error(e.getLocationAsString());
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111 | return "";
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112 | } catch (TransformerException e) {
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113 | logger.error("couldn't transform the source: " + e.getMessageAndLocation());
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114 | return "";
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115 | }
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116 | }
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117 |
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118 | public String transformToString(Document stylesheet, Document source) {
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119 | return transformToString(stylesheet, source, null);
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120 | }
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121 |
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122 | public String transformToString(Document stylesheet, Document source, HashMap parameters) {
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123 |
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124 | try {
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125 | // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
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126 | Transformer transformer = this.t_factory.newTransformer(new DOMSource(stylesheet));
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127 | transformer.setErrorListener(new TransformErrorListener());
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128 | if (parameters != null) {
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129 | Set params = parameters.entrySet();
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130 | Iterator i = params.iterator();
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131 | while (i.hasNext()) {
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132 | Map.Entry m = (Map.Entry)i.next();
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133 | transformer.setParameter((String)m.getKey(), m.getValue());
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134 | }
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135 | }
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136 | //transformer.setParameter("page_lang", source.getDocumentElement().getAttribute(GSXML.LANG_ATT));
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137 |
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138 |
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139 | // Use the Transformer to transform an XML Source and send the output to a Result object.
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140 | StringWriter output = new StringWriter();
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141 |
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142 | transformer.transform(new DOMSource(source), new StreamResult(output));
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143 | return output.toString();
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144 | } catch (TransformerConfigurationException e) {
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145 | logger.error("couldn't create transformer object: "+e.getMessageAndLocation());
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146 | logger.error(e.getLocationAsString());
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147 | return "";
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148 | } catch (TransformerException e) {
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149 | logger.error("couldn't transform the source: " + e.getMessageAndLocation());
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150 | return "";
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151 | }
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152 | }
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153 |
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154 | public Node transform(Document stylesheet, Document source) {
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155 | return transform(stylesheet, source, null, null);
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156 | }
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157 |
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158 | public Node transform(Document stylesheet, Document source, HashMap parameters, Document docDocType) {
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159 | try {
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160 | // Use the TransformerFactory to process the stylesheet Source and generate a Transformer.
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161 | Transformer transformer = this.t_factory.newTransformer(new DOMSource(stylesheet));
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162 | transformer.setErrorListener(new TransformErrorListener());
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163 | if (parameters != null) {
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164 | Set params = parameters.entrySet();
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165 | Iterator i = params.iterator();
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166 | while (i.hasNext()) {
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167 | Map.Entry m = (Map.Entry)i.next();
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168 | transformer.setParameter((String)m.getKey(), m.getValue());
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169 | }
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170 | }
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171 |
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172 | // When we transform the DOMResult, we need to make sure the result of
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173 | // the transformation has a DocType. For that to happen, we need to create
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174 | // the DOMResult using a Document with a predefined docType.
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175 | // If we don't have a DocType then do the transformation with a DOMResult
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176 | // that does not contain any doctype (like we use to do before).
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177 | DOMResult result = docDocType == null ? new DOMResult() : new DOMResult(docDocType);
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178 | transformer.transform(new DOMSource(source), result);
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179 | return result.getNode(); // pass the entire document
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180 | }
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181 | catch (TransformerConfigurationException e) {
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182 | return transformError("XMLTransformer.transform(Doc, Doc, HashMap, Doc)"
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183 | + "\ncouldn't create transformer object", e);
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184 | }
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185 | catch (TransformerException e) {
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186 | return transformError("XMLTransformer.transform(Doc, Doc, HashMap, Doc)"
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187 | + "\ncouldn't transform the source", e);
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188 | }
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189 | }
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190 |
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191 | public Node transform(File stylesheet, File source) {
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192 | try {
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193 | Transformer transformer = this.t_factory.newTransformer(new StreamSource(stylesheet));
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194 | transformer.setErrorListener(new TransformErrorListener());
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195 | DOMResult result = new DOMResult();
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196 | transformer.transform(new StreamSource(source), result);
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197 | return result.getNode().getFirstChild();
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198 | } catch (TransformerConfigurationException e) {
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199 | return transformError("XMLTransformer.transform(File, File)"
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200 | + "\ncouldn't create transformer object for files\n"
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201 | + stylesheet + "\n" + source, e);
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202 | }
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203 | catch (TransformerException e) {
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204 | return transformError("XMLTransformer.transform(File, File)"
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205 | + "\ncouldn't transform the source for files\n"
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206 | + stylesheet + "\n" + source, e);
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207 | }
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208 | }
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209 |
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210 | public Node transform(File stylesheet, File source, Document docDocType) {
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211 | try {
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212 | Transformer transformer = this.t_factory.newTransformer(new StreamSource(stylesheet));
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213 | transformer.setErrorListener(new TransformErrorListener());
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214 | DOMResult result = new DOMResult(docDocType);
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215 | transformer.transform(new StreamSource(source), result);
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216 | return result.getNode().getFirstChild();
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217 | } catch (TransformerConfigurationException e) {
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218 | return transformError("XMLTransformer.transform(File, File, Doc)"
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219 | + "\ncouldn't create transformer object for files\n"
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220 | + stylesheet + "\n" + source, e);
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221 | }
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222 | catch (TransformerException e) {
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223 | return transformError("XMLTransformer.transform(File, File, Doc)"
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224 | + "\ncouldn't transform the source for files\n"
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225 | + stylesheet + "\n" + source, e);
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226 | }
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227 | }
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228 |
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229 | // Given a heading string on the sort of transformation error that occurred and the exception object itself,
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230 | // this method prints the exception to the tomcat window (system.err) and the greenstone log and then returns
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231 | // an xhtml error page that is constructed from it.
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232 | protected Node transformError(String heading, TransformerException e) {
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233 | String message = heading + "\n" + e.getMessage();
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234 | logger.error(heading + ": " + e.getMessage());
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235 |
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236 | String location = e.getLocationAsString();
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237 | if(location != null) {
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238 | logger.error(location);
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239 | message = message + "\n" + location;
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240 | }
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241 | System.err.println("****\n" + message + "\n****");
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242 | return constructErrorXHTMLPage(message);
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243 | }
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244 |
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245 | // Given an error message, splits it into separate lines based on any newlines present and generates an xhtml page
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246 | // (xml Element) with paragraphs for each line. This is then returned so that it can be displayed in the browser.
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247 | public static Element constructErrorXHTMLPage(String message) {
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248 | try{
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249 | String[] lines = message.split("\n");
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250 |
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251 | Document xhtmlDoc = DocumentBuilderFactory.newInstance().newDocumentBuilder().newDocument();
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252 | // <html></html>
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253 | Node htmlNode = xhtmlDoc.createElement("html");
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254 | xhtmlDoc.appendChild(htmlNode);
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255 | // <head></head>
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256 | Node headNode = xhtmlDoc.createElement("head");
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257 | htmlNode.appendChild(headNode);
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258 | // <title></title>
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259 | Node titleNode = xhtmlDoc.createElement("title");
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260 | headNode.appendChild(titleNode);
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261 | Node titleString = xhtmlDoc.createTextNode("Error occurred");
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262 | titleNode.appendChild(titleString);
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263 |
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264 | // <body></body>
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265 | Node bodyNode = xhtmlDoc.createElement("body");
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266 | htmlNode.appendChild(bodyNode);
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267 |
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268 | // finally put the message in the body
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269 | Node h1Node = xhtmlDoc.createElement("h1");
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270 | bodyNode.appendChild(h1Node);
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271 | Node headingString = xhtmlDoc.createTextNode("The following error occurred:");
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272 | h1Node.appendChild(headingString);
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273 |
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274 | //Node textNode = xhtmlDoc.createTextNode(message);
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275 | //bodyNode.appendChild(textNode);
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276 |
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277 | for (int i = 0; i < lines.length; i++) {
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278 | Node pNode = xhtmlDoc.createElement("p");
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279 | Node textNode = xhtmlDoc.createTextNode(lines[i]);
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280 | pNode.appendChild(textNode);
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281 | bodyNode.appendChild(pNode);
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282 | }
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283 |
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284 | return xhtmlDoc.getDocumentElement();
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285 |
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286 | }catch(Exception e) {
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287 | String errmsg = "Exception trying to construct error xhtml page from message: " + message
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288 | + "\n" + e.getMessage();
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289 | System.err.println(errmsg);
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290 | logger.error(errmsg);
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291 | return null;
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292 | }
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293 | }
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294 |
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295 | // ErrorListener class that can be used to register a handler for any fatal errors, errors and warnings that may
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296 | // occur when transforming an xml file with an xslt stylesheet. The errors are printed both to the greenstone.log and
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297 | // to the tomcat console (System.err), and the error message is stored in the errorMessage variable so that it can
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298 | // be retrieved and be used to generate an xhtml error page.
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299 | static public class TransformErrorListener implements ErrorListener {
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300 | protected String errorMessage = null;
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301 |
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302 | // Receive notification of a recoverable error.
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303 | public void error(TransformerException exception) {
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304 | handleError("Error:\n", exception);
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305 | }
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306 | // Receive notification of a non-recoverable error.
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307 | public void fatalError(TransformerException exception) {
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308 | handleError("Fatal Error:\n", exception);
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309 | }
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310 | // Receive notification of a warning.
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311 | public void warning(TransformerException exception) {
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312 | handleError("Warning:\n", exception);
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313 | }
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314 |
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315 | public String toString(TransformerException e) {
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316 | String location = e.getLocationAsString();
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317 | if(location == null) {
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318 | return e.getMessage();
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319 | }
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320 | return e.getMessage() + "\n" + location;
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321 | }
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322 |
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323 | // clears the errorPage variable after first call to this method
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324 | public String getErrorMessage() {
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325 | String errMsg = this.errorMessage;
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326 | if(this.errorMessage != null) {
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327 | this.errorMessage = null;
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328 | }
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329 | return errMsg;
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330 | }
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331 |
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332 | // sets the errorMessage member variable to the data stored in the exception
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333 | // and writes the errorMessage to the logger and tomcat's System.err
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334 | protected void handleError(String errorType, TransformerException exception) {
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335 | this.errorMessage = errorType + toString(exception);
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336 | System.err.println("\n****Error transforming xml:\n" + this.errorMessage + "\n****\n");
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337 | logger.error(this.errorMessage);
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338 | }
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339 | }
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340 | } |
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