1 | /** |
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2 | * This software is copyright (c) 2011-2022 by |
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3 | * - Leibniz-Institut fuer Deutsche Sprache (http://www.ids-mannheim.de) |
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4 | * This is free software. You can redistribute it |
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5 | * and/or modify it under the terms described in |
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6 | * the GNU General Public License v3 of which you |
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7 | * should have received a copy. Otherwise you can download |
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8 | * it from |
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9 | * |
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10 | * http://www.gnu.org/licenses/gpl-3.0.txt |
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11 | * |
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12 | * @copyright Leibniz-Institut fuer Deutsche Sprache (http://www.ids-mannheim.de) |
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13 | * |
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14 | * @license http://www.gnu.org/licenses/gpl-3.0.txt |
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15 | * GNU General Public License v3 |
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16 | */ |
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17 | package eu.clarin.sru.server; |
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18 | |
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19 | import java.io.IOException; |
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20 | import java.io.OutputStream; |
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21 | import java.io.OutputStreamWriter; |
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22 | import java.io.StringReader; |
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23 | import java.io.Writer; |
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24 | import java.util.ArrayDeque; |
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25 | import java.util.Deque; |
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26 | |
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27 | import javax.xml.namespace.NamespaceContext; |
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28 | import javax.xml.parsers.SAXParser; |
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29 | import javax.xml.parsers.SAXParserFactory; |
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30 | import javax.xml.stream.XMLOutputFactory; |
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31 | import javax.xml.stream.XMLStreamException; |
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32 | import javax.xml.stream.XMLStreamWriter; |
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33 | |
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34 | import org.xml.sax.Attributes; |
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35 | import org.xml.sax.InputSource; |
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36 | import org.xml.sax.SAXException; |
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37 | import org.xml.sax.helpers.DefaultHandler; |
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38 | import org.z3950.zing.cql.CQLNode; |
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39 | |
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40 | final class SRUXMLStreamWriter implements XMLStreamWriter { |
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41 | private enum IndentingState { |
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42 | SEEN_NOTHING, |
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43 | SEEN_ELEMENT, |
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44 | SEEN_DATA |
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45 | } |
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46 | private static final SAXParserFactory factory; |
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47 | private final SRURecordXmlEscaping recordEscaping; |
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48 | private final Writer writer; |
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49 | private final XMLStreamWriter xmlwriter; |
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50 | private int indent = -1; |
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51 | private int depth = 0; |
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52 | private Deque<IndentingState> stateStack; |
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53 | private IndentingState state; |
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54 | private boolean writingRecord = false; |
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55 | |
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56 | |
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57 | SRUXMLStreamWriter(OutputStream stream, |
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58 | XMLOutputFactory factory, |
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59 | SRURecordXmlEscaping recordXmlEscaping, |
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60 | int indent) throws IOException, XMLStreamException { |
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61 | this.recordEscaping = recordXmlEscaping; |
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62 | this.writer = new OutputStreamWriter(stream, |
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63 | SRUServer.RESPONSE_ENCODING) { |
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64 | @Override |
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65 | public void write(int c) throws IOException { |
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66 | if (writingRecord && (recordEscaping == SRURecordXmlEscaping.STRING)) { |
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67 | /* |
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68 | * NOTE: need to write single characters here, because |
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69 | * super.write(String) will call us again, and we would |
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70 | * create and endless loop here until stack blows up ... |
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71 | */ |
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72 | switch (c) { |
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73 | case '<': |
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74 | super.write('&'); |
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75 | super.write('l'); |
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76 | super.write('t'); |
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77 | super.write(';'); |
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78 | return; |
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79 | case '>': |
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80 | super.write('&'); |
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81 | super.write('g'); |
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82 | super.write('t'); |
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83 | super.write(';'); |
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84 | return; |
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85 | case '&': |
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86 | super.write('&'); |
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87 | super.write('a'); |
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88 | super.write('m'); |
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89 | super.write('p'); |
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90 | super.write(';'); |
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91 | return; |
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92 | default: |
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93 | /* $FALL-THROUGH$ */ |
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94 | } |
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95 | } |
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96 | super.write(c); |
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97 | } |
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98 | |
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99 | @Override |
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100 | public void write(char[] c, int off, int len) throws IOException { |
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101 | if (writingRecord && (recordEscaping == SRURecordXmlEscaping.STRING)) { |
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102 | for (int i = off; i < len; i++) { |
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103 | this.write(c[i]); |
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104 | } |
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105 | } else { |
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106 | super.write(c, off, len); |
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107 | } |
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108 | } |
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109 | |
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110 | @Override |
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111 | public void write(String s, int off, int len) throws IOException { |
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112 | if (writingRecord && (recordEscaping == SRURecordXmlEscaping.STRING)) { |
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113 | for (int i = off; i < len; i++) { |
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114 | this.write(s.charAt(i)); |
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115 | } |
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116 | } else { |
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117 | super.write(s, off, len); |
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118 | } |
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119 | } |
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120 | }; |
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121 | |
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122 | /* |
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123 | * It is believed, that XMLWriterFactories, once configured, |
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124 | * are thread-save ... |
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125 | */ |
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126 | this.xmlwriter = factory.createXMLStreamWriter(this.writer); |
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127 | |
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128 | if (indent > 0) { |
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129 | this.indent = indent; |
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130 | this.state = IndentingState.SEEN_NOTHING; |
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131 | this.stateStack = new ArrayDeque<IndentingState>(16); |
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132 | } |
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133 | } |
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134 | |
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135 | |
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136 | @Override |
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137 | public void writeStartElement(String localName) throws XMLStreamException { |
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138 | if (indent > 0) { |
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139 | onStartElement(); |
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140 | } |
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141 | xmlwriter.writeStartElement(localName); |
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142 | } |
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143 | |
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144 | |
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145 | @Override |
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146 | public void writeStartElement(String namespaceURI, String localName) |
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147 | throws XMLStreamException { |
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148 | if (indent > 0) { |
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149 | onStartElement(); |
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150 | } |
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151 | xmlwriter.writeStartElement(namespaceURI, localName); |
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152 | } |
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153 | |
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154 | |
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155 | @Override |
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156 | public void writeStartElement(String prefix, String localName, |
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157 | String namespaceURI) throws XMLStreamException { |
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158 | if (indent > 0) { |
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159 | onStartElement(); |
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160 | } |
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161 | xmlwriter.writeStartElement(prefix, localName, namespaceURI); |
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162 | } |
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163 | |
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164 | |
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165 | @Override |
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166 | public void writeEmptyElement(String namespaceURI, String localName) |
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167 | throws XMLStreamException { |
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168 | if (indent > 0) { |
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169 | onEmptyElement(); |
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170 | } |
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171 | xmlwriter.writeEmptyElement(namespaceURI, localName); |
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172 | } |
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173 | |
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174 | |
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175 | @Override |
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176 | public void writeEmptyElement(String prefix, String localName, |
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177 | String namespaceURI) throws XMLStreamException { |
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178 | if (indent > 0) { |
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179 | onEmptyElement(); |
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180 | } |
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181 | xmlwriter.writeEmptyElement(prefix, localName, namespaceURI); |
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182 | } |
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183 | |
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184 | |
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185 | @Override |
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186 | public void writeEmptyElement(String localName) throws XMLStreamException { |
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187 | if (indent > 0) { |
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188 | onEmptyElement(); |
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189 | } |
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190 | xmlwriter.writeEmptyElement(localName); |
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191 | } |
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192 | |
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193 | |
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194 | @Override |
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195 | public void writeEndElement() throws XMLStreamException { |
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196 | if (indent > 0) { |
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197 | onEndElement(); |
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198 | } |
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199 | xmlwriter.writeEndElement(); |
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200 | } |
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201 | |
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202 | |
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203 | @Override |
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204 | public void writeEndDocument() throws XMLStreamException { |
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205 | xmlwriter.writeEndDocument(); |
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206 | } |
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207 | |
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208 | |
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209 | @Override |
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210 | public void close() throws XMLStreamException { |
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211 | xmlwriter.close(); |
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212 | } |
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213 | |
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214 | |
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215 | @Override |
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216 | public void flush() throws XMLStreamException { |
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217 | xmlwriter.flush(); |
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218 | } |
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219 | |
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220 | |
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221 | @Override |
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222 | public void writeAttribute(String localName, String value) |
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223 | throws XMLStreamException { |
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224 | xmlwriter.writeAttribute(localName, value); |
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225 | } |
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226 | |
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227 | |
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228 | @Override |
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229 | public void writeAttribute(String prefix, String namespaceURI, |
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230 | String localName, String value) throws XMLStreamException { |
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231 | xmlwriter.writeAttribute(prefix, namespaceURI, localName, value); |
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232 | } |
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233 | |
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234 | |
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235 | @Override |
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236 | public void writeAttribute(String namespaceURI, String localName, |
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237 | String value) throws XMLStreamException { |
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238 | xmlwriter.writeAttribute(namespaceURI, localName, value); |
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239 | } |
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240 | |
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241 | |
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242 | @Override |
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243 | public void writeNamespace(String prefix, String namespaceURI) |
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244 | throws XMLStreamException { |
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245 | xmlwriter.writeNamespace(prefix, namespaceURI); |
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246 | } |
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247 | |
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248 | |
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249 | @Override |
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250 | public void writeDefaultNamespace(String namespaceURI) |
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251 | throws XMLStreamException { |
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252 | xmlwriter.writeDefaultNamespace(namespaceURI); |
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253 | } |
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254 | |
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255 | |
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256 | @Override |
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257 | public void writeComment(String data) throws XMLStreamException { |
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258 | xmlwriter.writeComment(data); |
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259 | } |
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260 | |
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261 | |
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262 | @Override |
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263 | public void writeProcessingInstruction(String target) |
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264 | throws XMLStreamException { |
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265 | xmlwriter.writeProcessingInstruction(target); |
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266 | } |
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267 | |
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268 | |
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269 | @Override |
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270 | public void writeProcessingInstruction(String target, String data) |
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271 | throws XMLStreamException { |
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272 | xmlwriter.writeProcessingInstruction(target, data); |
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273 | } |
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274 | |
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275 | |
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276 | @Override |
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277 | public void writeCData(String data) throws XMLStreamException { |
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278 | if (indent > 0) { |
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279 | state = IndentingState.SEEN_DATA; |
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280 | } |
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281 | xmlwriter.writeCData(data); |
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282 | } |
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283 | |
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284 | |
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285 | @Override |
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286 | public void writeDTD(String dtd) throws XMLStreamException { |
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287 | xmlwriter.writeDTD(dtd); |
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288 | } |
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289 | |
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290 | |
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291 | @Override |
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292 | public void writeEntityRef(String name) throws XMLStreamException { |
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293 | xmlwriter.writeEntityRef(name); |
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294 | } |
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295 | |
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296 | |
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297 | @Override |
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298 | public void writeStartDocument() throws XMLStreamException { |
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299 | xmlwriter.writeStartDocument(); |
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300 | if (indent > 0) { |
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301 | xmlwriter.writeCharacters("\n"); |
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302 | } |
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303 | } |
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304 | |
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305 | |
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306 | @Override |
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307 | public void writeStartDocument(String version) throws XMLStreamException { |
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308 | xmlwriter.writeStartDocument(version); |
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309 | if (indent > 0) { |
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310 | xmlwriter.writeCharacters("\n"); |
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311 | } |
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312 | } |
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313 | |
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314 | |
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315 | @Override |
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316 | public void writeStartDocument(String encoding, String version) |
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317 | throws XMLStreamException { |
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318 | xmlwriter.writeStartDocument(encoding, version); |
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319 | if (indent > 0) { |
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320 | xmlwriter.writeCharacters("\n"); |
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321 | } |
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322 | } |
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323 | |
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324 | |
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325 | @Override |
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326 | public void writeCharacters(String text) throws XMLStreamException { |
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327 | if (indent > 0) { |
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328 | state = IndentingState.SEEN_DATA; |
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329 | } |
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330 | xmlwriter.writeCharacters(text); |
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331 | } |
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332 | |
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333 | |
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334 | @Override |
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335 | public void writeCharacters(char[] text, int start, int len) |
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336 | throws XMLStreamException { |
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337 | if (indent > 0) { |
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338 | state = IndentingState.SEEN_DATA; |
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339 | } |
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340 | xmlwriter.writeCharacters(text, start, len); |
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341 | } |
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342 | |
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343 | |
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344 | @Override |
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345 | public String getPrefix(String uri) throws XMLStreamException { |
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346 | return xmlwriter.getPrefix(uri); |
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347 | } |
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348 | |
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349 | |
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350 | @Override |
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351 | public void setPrefix(String prefix, String uri) throws XMLStreamException { |
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352 | xmlwriter.setPrefix(prefix, uri); |
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353 | } |
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354 | |
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355 | |
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356 | @Override |
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357 | public void setDefaultNamespace(String uri) throws XMLStreamException { |
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358 | xmlwriter.setDefaultNamespace(uri); |
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359 | } |
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360 | |
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361 | |
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362 | @Override |
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363 | public void setNamespaceContext(NamespaceContext context) |
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364 | throws XMLStreamException { |
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365 | xmlwriter.setNamespaceContext(context); |
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366 | } |
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367 | |
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368 | |
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369 | @Override |
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370 | public NamespaceContext getNamespaceContext() { |
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371 | return xmlwriter.getNamespaceContext(); |
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372 | } |
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373 | |
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374 | |
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375 | @Override |
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376 | public Object getProperty(String name) throws IllegalArgumentException { |
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377 | return xmlwriter.getProperty(name); |
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378 | } |
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379 | |
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380 | |
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381 | public Writer getWriter() { |
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382 | return writer; |
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383 | } |
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384 | |
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385 | |
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386 | public void startRecord() throws XMLStreamException { |
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387 | if (writingRecord) { |
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388 | throw new IllegalStateException("was already writing record"); |
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389 | } |
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390 | xmlwriter.flush(); |
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391 | /* |
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392 | * abuse writeCharacters to force writer to close finish |
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393 | * any pending start or end elements |
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394 | */ |
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395 | xmlwriter.writeCharacters(""); |
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396 | writingRecord = true; |
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397 | } |
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398 | |
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399 | |
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400 | public void endRecord() throws XMLStreamException { |
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401 | if (!writingRecord) { |
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402 | throw new IllegalStateException("was not writing record"); |
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403 | } |
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404 | /* |
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405 | * abuse writeCharacters to force writer to close finish |
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406 | * any pending start or end elements |
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407 | */ |
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408 | xmlwriter.writeCharacters(""); |
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409 | xmlwriter.flush(); |
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410 | writingRecord = false; |
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411 | } |
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412 | |
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413 | |
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414 | public void writeXCQL(CQLNode query, final boolean searchRetrieveMode) |
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415 | throws XMLStreamException { |
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416 | /* |
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417 | * HACK: Parsing the XCQL to serialize is wasting resources. |
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418 | * Alternative would be to serialize to XCQL from CQLNode, but |
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419 | * I'm not yet enthusiastic on writing the serializer myself. |
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420 | */ |
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421 | try { |
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422 | SAXParser parser = factory.newSAXParser(); |
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423 | InputSource input = |
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424 | new InputSource(new StringReader(query.toXCQL())); |
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425 | parser.parse(input, new DefaultHandler() { |
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426 | @Override |
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427 | public void startElement(String uri, String localName, |
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428 | String qName, Attributes attributes) |
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429 | throws SAXException { |
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430 | if (!searchRetrieveMode && qName.equals("searchClause")) { |
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431 | return; |
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432 | } |
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433 | try { |
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434 | SRUXMLStreamWriter.this.writeStartElement(qName); |
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435 | for (int i = 0; i < attributes.getLength(); i++) { |
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436 | SRUXMLStreamWriter.this.writeAttribute(attributes.getQName(i), |
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437 | attributes.getValue(i)); |
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438 | } |
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439 | } catch (XMLStreamException e) { |
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440 | throw new SAXException(e); |
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441 | } |
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442 | } |
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443 | |
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444 | @Override |
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445 | public void endElement(String uri, String localName, |
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446 | String qName) throws SAXException { |
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447 | if (!searchRetrieveMode && qName.equals("searchClause")) { |
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448 | return; |
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449 | } |
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450 | try { |
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451 | SRUXMLStreamWriter.this.writeEndElement(); |
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452 | } catch (XMLStreamException e) { |
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453 | throw new SAXException(e); |
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454 | } |
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455 | } |
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456 | |
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457 | @Override |
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458 | public void characters(char[] text, int start, int length) |
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459 | throws SAXException { |
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460 | try { |
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461 | boolean isWhitespaceOnly = true; |
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462 | for (int i = start; i < start + length; i++) { |
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463 | if (!Character.isWhitespace(text[i])) { |
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464 | isWhitespaceOnly = false; |
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465 | break; |
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466 | } |
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467 | } |
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468 | if (!isWhitespaceOnly) { |
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469 | SRUXMLStreamWriter.this.writeCharacters(text, start, length); |
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470 | } |
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471 | } catch (XMLStreamException e) { |
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472 | throw new SAXException(e); |
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473 | } |
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474 | } |
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475 | }); |
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476 | } catch (Exception e) { |
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477 | throw new XMLStreamException("cannot write XCQL", e); |
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478 | } |
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479 | } |
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480 | |
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481 | |
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482 | private void onStartElement() throws XMLStreamException { |
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483 | if (!(writingRecord && (recordEscaping == SRURecordXmlEscaping.STRING))) { |
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484 | stateStack.push(IndentingState.SEEN_ELEMENT); |
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485 | state = IndentingState.SEEN_NOTHING; |
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486 | if (depth > 0) { |
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487 | xmlwriter.writeCharacters("\n"); |
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488 | } |
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489 | doIndent(); |
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490 | depth++; |
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491 | } |
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492 | } |
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493 | |
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494 | |
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495 | private void onEndElement() throws XMLStreamException { |
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496 | if (!(writingRecord && (recordEscaping == SRURecordXmlEscaping.STRING))) { |
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497 | depth--; |
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498 | if (state == IndentingState.SEEN_ELEMENT) { |
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499 | xmlwriter.writeCharacters("\n"); |
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500 | doIndent(); |
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501 | } |
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502 | state = stateStack.pop(); |
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503 | } |
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504 | } |
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505 | |
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506 | |
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507 | private void onEmptyElement() throws XMLStreamException { |
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508 | if (!(writingRecord && (recordEscaping == SRURecordXmlEscaping.STRING))) { |
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509 | state = IndentingState.SEEN_ELEMENT; |
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510 | if (depth > 0) { |
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511 | xmlwriter.writeCharacters("\n"); |
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512 | } |
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513 | doIndent(); |
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514 | } |
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515 | } |
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516 | |
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517 | |
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518 | private void doIndent() throws XMLStreamException { |
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519 | if (depth > 0) { |
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520 | for (int i = 0; i < (depth * indent); i++) { |
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521 | xmlwriter.writeCharacters(" "); |
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522 | } |
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523 | } |
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524 | } |
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525 | |
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526 | |
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527 | static { |
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528 | factory = SAXParserFactory.newInstance(); |
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529 | factory.setNamespaceAware(false); |
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530 | factory.setValidating(false); |
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531 | factory.setXIncludeAware(false); |
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532 | } |
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533 | |
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534 | } // class SRUXMLStreamWriter |
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