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1
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1 /* XMLListLoader -- Load an XML list into a Hashtable
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2
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3 Digital Image Library servlet components
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4
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5 Copyright (C) 2001, 2002 Robert Casties (robcast@mail.berlios.de)
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6
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7 This program is free software; you can redistribute it and/or modify it
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8 under the terms of the GNU General Public License as published by the
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9 Free Software Foundation; either version 2 of the License, or (at your
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10 option) any later version.
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11
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12 Please read license.txt for the full details. A copy of the GPL
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13 may be found at http://www.gnu.org/copyleft/lgpl.html
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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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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18
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19 */
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20
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21 package digilib.io;
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22
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23 // JAXP packages
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88
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24 import java.io.IOException;
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25 import java.util.HashMap;
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26 import java.util.LinkedList;
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1
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27
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88
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28 import javax.xml.parsers.ParserConfigurationException;
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29 import javax.xml.parsers.SAXParser;
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30 import javax.xml.parsers.SAXParserFactory;
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31
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181
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32 import org.apache.log4j.Logger;
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88
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33 import org.xml.sax.Attributes;
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34 import org.xml.sax.SAXException;
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35 import org.xml.sax.SAXParseException;
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140
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36 import org.xml.sax.helpers.DefaultHandler;
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1
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37
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176
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38 /** Loads a simple XML list into a HashMap.
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39 *
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40 * The XML file has an outer <code>list_tag</code>. Every entry is an
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41 * <code>entry_tag</code> with two attributes: the <code>key_att</code>
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42 * key and the <code>value_att</code> value.
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43 *
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44 * The file is read by the <code>loadURL</code> method, that returns a
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45 * HashMap with the key-value pairs.
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46 *
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47 * @author casties
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48 */
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1
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49 public class XMLListLoader {
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50
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181
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51 private Logger logger = Logger.getLogger(this.getClass());
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88
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52 private String listTag = "list";
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53 private String entryTag = "entry";
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54 private String keyAtt = "key";
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55 private String valueAtt = "value";
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1
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56
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88
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57 public XMLListLoader() {
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58 }
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1
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59
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88
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60 public XMLListLoader(
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61 String list_tag,
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62 String entry_tag,
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63 String key_att,
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64 String value_att) {
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181
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65 logger.debug("xmlListLoader("+list_tag+","+entry_tag+","+key_att+","+value_att+")");
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88
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66 listTag = list_tag;
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67 entryTag = entry_tag;
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68 keyAtt = key_att;
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69 valueAtt = value_att;
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70 }
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1
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71
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88
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72 /**
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73 * inner class XMLListParser to be called by the parser
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74 */
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140
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75 private class XMLListParser extends DefaultHandler {
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88
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76
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77 private HashMap listData;
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138
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78 private LinkedList tagSpace;
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88
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79
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80 public HashMap getData() {
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81 return listData;
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82 }
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1
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83
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88
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84 // Parser calls this once at the beginning of a document
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85 public void startDocument() throws SAXException {
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86 listData = new HashMap();
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138
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87 tagSpace = new LinkedList();
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88
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88 }
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89
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88
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90 // Parser calls this for each element in a document
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91 public void startElement(
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92 String namespaceURI,
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93 String localName,
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94 String qName,
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95 Attributes atts)
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96 throws SAXException {
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97 //System.out.println("<"+qName);
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98 // open a new namespace
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99 tagSpace.addLast(qName);
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100
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101 // ist it an entry tag?
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102 if (qName.equals(entryTag)) {
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103 // is it inside a list tag?
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138
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104 if ((listTag.length() > 0) && (!tagSpace.contains(listTag))) {
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181
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105 logger.error("BOO: Entry "
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88
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106 + entryTag
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107 + " not inside list "
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108 + listTag);
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109 throw new SAXParseException(
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110 "Entry " + entryTag + " not inside list " + listTag,
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111 null);
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112 }
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113 // get the attributes
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114 String key = atts.getValue(keyAtt);
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115 String val = atts.getValue(valueAtt);
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116 if ((key == null) || (val == null)) {
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181
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117 logger.error("BOO: Entry "
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88
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118 + entryTag
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119 + " does not have Attributes "
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120 + keyAtt
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121 + ", "
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122 + valueAtt);
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123 throw new SAXParseException(
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124 "Entry "
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125 + entryTag
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126 + " does not have Attributes "
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127 + keyAtt
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128 + ", "
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129 + valueAtt,
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130 null);
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131 }
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132 // add the values
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133 //System.out.println("DATA: "+key+" = "+val);
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134 listData.put(key, val);
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135 }
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136 }
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1
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137
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88
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138 public void endElement(
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139 String namespaceURI,
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140 String localName,
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141 String qName)
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142 throws SAXException {
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143 // exit the namespace
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138
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144 tagSpace.removeLast();
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145 }
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1
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146
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88
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147 }
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148
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149 /**
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150 * load and parse a file (as URL)
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151 * returns HashMap with list data
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152 */
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153 public HashMap loadURL(String path) throws SAXException, IOException {
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154 //System.out.println("loadurl ("+path+")");
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155 // Create a JAXP SAXParserFactory and configure it
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156 SAXParserFactory spf = SAXParserFactory.newInstance();
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138
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157 spf.setNamespaceAware(true);
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1
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158
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138
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159 SAXParser parser = null;
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88
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160 try {
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161 // Create a JAXP SAXParser
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138
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162 parser = spf.newSAXParser();
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88
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163
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164 } catch (ParserConfigurationException e) {
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165 throw new SAXException(e);
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166 }
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1
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167
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88
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168 // create a list parser (keeps the data!)
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169 XMLListParser listParser = new XMLListParser();
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1
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170
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138
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171 // Tell the SAXParser to parse the XML document
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172 parser.parse(path, listParser);
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1
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173
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88
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174 return listParser.getData();
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175 }
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1
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176
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177 }
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