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2 | Licensed to the Apache Software Foundation (ASF) under one or more
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9 | http://www.apache.org/licenses/LICENSE-2.0
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11 | Unless required by applicable law or agreed to in writing, software
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12 | distributed under the License is distributed on an "AS IS" BASIS,
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17 | <html>
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18 |
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19 | <head>
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20 | <meta http-equiv="Content-Language" content="en-us">
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21 | <link rel="stylesheet" type="text/css" href="../stylesheets/style.css">
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22 | <title>Javah Task</title>
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23 | </head>
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24 |
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25 | <body>
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26 |
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27 | <h2><a name="javah">Javah</a></h2>
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28 | <h3>Description</h3>
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29 | <p>Generates JNI headers from a Java class.</p>
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30 | <p> When this task executes, it will generate the C header and source files that
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31 | are needed to implement native methods. JNI operates differently depending on
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32 | whether <a href="http://java.sun.com/j2se/1.3/docs/tooldocs/win32/javah.html">JDK1.2</a>
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33 | (or later) or <a href="http://java.sun.com/products/jdk/1.1/docs/tooldocs/win32/javah.html">pre-JDK1.2</a>
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34 | systems are used.</p>
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35 |
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36 | <p>It is possible to use different compilers. This can be selected
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37 | with the <code>implementation</code> attribute. <a
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38 | name="implementationvalues">Here are the choices</a>:</p>
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39 | <ul>
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40 | <li>default - the default compiler (kaffeh or sun) for the platform.</li>
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41 | <li>sun (the standard compiler of the JDK)</li>
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42 | <li>kaffeh (the native standard compiler of <a href="http://www.kaffe.org" target="_top">Kaffe</a>)</li>
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43 | </ul>
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44 |
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45 | <h3>Parameters</h3>
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46 | <table border="1" cellpadding="2" cellspacing="0">
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47 | <tr>
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48 | <td valign="top"><b>Attribute</b></td>
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49 | <td valign="top"><b>Description</b></td>
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50 | <td valign="top" align="center"><b>Required</b></td>
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51 | </tr>
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52 | <tr>
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53 | <td valign="top">class</td>
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54 | <td valign="top">the fully-qualified name of the class (or classes,
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55 | separated by commas)</td>
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56 | <td align="center" valign="top">Yes</td>
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57 | </tr>
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58 | <tr>
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59 | <td valign="top">outputFile</td>
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60 | <td valign="top">concatenates the resulting header or source files for all the classes listed into this file</td>
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61 | <td align="center" valign="middle" rowspan="2">Yes</td>
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62 | </tr>
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63 | <tr>
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64 | <td valign="top">destdir</td>
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65 | <td valign="top">sets the directory where javah saves the header files or the
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66 | stub files.</td>
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67 | </tr>
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68 | <tr>
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69 | <td valign="top">force</td>
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70 | <td valign="top">specifies that output files should always be written (JDK1.2 only)</td>
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71 | <td valign="top" align="center">No</td>
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72 | </tr>
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73 | <tr>
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74 | <td valign="top">old</td>
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75 | <td valign="top">specifies that old JDK1.0-style header files should be generated
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76 | (otherwise output file contain JNI-style native method function prototypes) (JDK1.2 only)</td>
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77 | <td valign="top" align="center">No</td>
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78 | </tr>
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79 | <tr>
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80 | <td valign="top">stubs</td>
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81 | <td valign="top">generate C declarations from the Java object file (used with old)</td>
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82 | <td valign="top" align="center">No</td>
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83 | </tr>
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84 | <tr>
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85 | <td valign="top">verbose</td>
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86 | <td valign="top">causes Javah to print a message concerning the status of the generated files</td>
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87 | <td valign="top" align="center">No</td>
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88 | </tr>
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89 | <tr>
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90 | <td valign="top">classpath</td>
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91 | <td valign="top">the classpath to use.</td>
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92 | <td align="center" valign="top">No</td>
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93 | </tr>
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94 | <tr>
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95 | <td valign="top">bootclasspath</td>
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96 | <td valign="top">location of bootstrap class files.</td>
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97 | <td valign="top" align="center">No</td>
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98 | </tr>
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99 | <tr>
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100 | <td valign="top">extdirs</td>
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101 | <td valign="top"> location of installed extensions.</td>
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102 | <td valign="top" align="center">No</td>
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103 | </tr>
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104 | <tr>
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105 | <td valign="top">implementation</td>
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106 | <td valign="top">The compiler implementation to use. If this
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107 | attribute is not set, the default compiler for the current VM
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108 | will be used. (See the above <a
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109 | href="#implementationvalues">list</a> of valid compilers.)</td>
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110 | <td align="center" valign="top">No</td>
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111 | </tr>
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112 | </table>
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113 | <p>Either outputFile or destdir must be supplied, but not both. </p>
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114 |
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115 | <h3>Parameters specified as nested elements</h3>
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116 |
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117 | <h4>arg</h4>
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118 |
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119 | <p>You can specify additional command line arguments for the compiler
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120 | with nested <code><arg></code> elements. These elements are
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121 | specified like <a href="../using.html#arg">Command-line Arguments</a>
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122 | but have an additional attribute that can be used to enable arguments
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123 | only if a given compiler implementation will be used.</p>
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124 |
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125 | <table border="1" cellpadding="2" cellspacing="0">
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126 | <tr>
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127 | <td width="12%" valign="top"><b>Attribute</b></td>
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128 | <td width="78%" valign="top"><b>Description</b></td>
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129 | <td width="10%" valign="top"><b>Required</b></td>
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130 | </tr>
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131 | <tr>
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132 | <td valign="top">value</td>
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133 | <td align="center" rowspan="4">See
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134 | <a href="../using.html#arg">Command-line Arguments</a>.</td>
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135 | <td align="center" rowspan="4">Exactly one of these.</td>
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136 | </tr>
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137 | <tr>
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138 | <td valign="top">line</td>
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139 | </tr>
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140 | <tr>
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141 | <td valign="top">file</td>
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142 | </tr>
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143 | <tr>
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144 | <td valign="top">path</td>
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145 | </tr>
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146 | <tr>
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147 | <td valign="top">implementation</td>
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148 | <td>Only pass the specified argument if the chosen compiler
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149 | implementation matches the value of this attribute. Legal values
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150 | are the same as those in the above <a
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151 | href="#implementationvalues">list</a> of valid compilers.)</td>
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152 | <td align="center">No</td>
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153 | </tr>
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154 | </table>
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155 |
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156 | <h3>Examples</h3>
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157 | <pre> <javah destdir="c" class="org.foo.bar.Wibble"/></pre>
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158 | <p>makes a JNI header of the named class, using the JDK1.2 JNI model. Assuming
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159 | the directory 'c' already exists, the file <tt>org_foo_bar_Wibble.h</tt>
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160 | is created there. If this file already exists, it is left unchanged.</p>
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161 | <pre> <javah outputFile="wibble.h">
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162 | <class name="org.foo.bar.Wibble,org.foo.bar.Bobble"/>
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163 | </javah></pre>
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164 | <p>is similar to the previous example, except the output is written to a file
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165 | called <tt>wibble.h</tt>
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166 | in the current directory.</p>
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167 | <pre> <javah destdir="c" force="yes">
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168 | <class name="org.foo.bar.Wibble"/>
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169 | <class name="org.foo.bar.Bobble"/>
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170 | <class name="org.foo.bar.Tribble"/>
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171 | </javah></pre>
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172 | <p>writes three header files, one for each of the classes named. Because the
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173 | force option is set, these header files are always written when the Javah task
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174 | is invoked, even if they already exist.</p>
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175 | <pre> <javah destdir="c" verbose="yes" old="yes" force="yes">
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176 | <class name="org.foo.bar.Wibble"/>
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177 | <class name="org.foo.bar.Bobble"/>
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178 | <class name="org.foo.bar.Tribble"/>
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179 | </javah>
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180 | <javah destdir="c" verbose="yes" stubs="yes" old="yes" force="yes">
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181 | <class name="org.foo.bar.Wibble"/>
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182 | <class name="org.foo.bar.Bobble"/>
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183 | <class name="org.foo.bar.Tribble"/>
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184 | </javah></pre>
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185 | <p>writes the headers for the three classes using the 'old' JNI format, then
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186 | writes the corresponding .c stubs. The verbose option will cause Javah to
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187 | describe its progress.</p>
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188 |
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189 |
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190 | </body>
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191 |
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192 | </html>
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