1 | |
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2 | ~~ Licensed to the Apache Software Foundation (ASF) under one |
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3 | ~~ or more contributor license agreements. See the NOTICE file |
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4 | ~~ distributed with this work for additional information |
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5 | ~~ regarding copyright ownership. The ASF licenses this file |
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6 | ~~ to you under the Apache License, Version 2.0 (the |
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7 | ~~ "License"); you may not use this file except in compliance |
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8 | ~~ with the License. You may obtain a copy of the License at |
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9 | ~~ |
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10 | ~~ http://www.apache.org/licenses/LICENSE-2.0 |
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11 | ~~ |
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12 | ~~ Unless required by applicable law or agreed to in writing, |
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13 | ~~ software distributed under the License is distributed on an |
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14 | ~~ "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY |
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15 | ~~ KIND, either express or implied. See the License for the |
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16 | ~~ specific language governing permissions and limitations |
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17 | ~~ under the License. |
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18 | |
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19 | ------------- |
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20 | Usage |
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21 | ------------- |
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22 | |
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23 | {Usage} |
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24 | |
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25 | Mime4j provides two different API's: An event based API by using |
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26 | the {{{apidocs/org/apache/james/mime4j/parser/MimeStreamParser.html} |
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27 | MimeStreamParser}}. Alternatively, you may use the iterative |
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28 | API, which is available through the |
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29 | {{{apidocs/org/apache/james/mime4j/parser/MimeTokenStream.html} |
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30 | MimeTokenStream}}. In terms of speed, you should not note |
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31 | any differences. |
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32 | |
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33 | * {{{#Token Streams}Token Streams}} |
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34 | |
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35 | * {{{#Sample Token Stream}Sample Token Stream}} |
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36 | |
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37 | * {{{#Event Handlers}Event Handlers}} |
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38 | |
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39 | * {{{#Sample Event Stream}Sample Event Stream}} |
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40 | |
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41 | {Token Streams} |
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42 | |
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43 | The iterative approach is using the class |
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44 | {{{apidocs/org/apache/james/mime4j/parser/MimeTokenStream.html} |
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45 | MimeTokenStream}}. Here's an example, how you could use |
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46 | the token stream: |
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47 | |
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48 | -------------------------------------------------------------------- |
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49 | MimeTokenStream stream = new MimeTokenStream(); |
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50 | stream.parse(new BufferedInputStream(new FileInputStream("mime.msg"))); |
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51 | for (int state = stream.getState(); |
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52 | state != MimeTokenStream.T_END_OF_STREAM; |
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53 | state = stream.next()) { |
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54 | switch (state) { |
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55 | case MimeTokenStream.T_BODY: |
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56 | System.out.println("Body detected, contents = " |
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57 | + stream.getInputStream() + ", header data = " |
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58 | + stream.getBodyDescriptor()); |
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59 | break; |
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60 | case MimeTokenStream.T_FIELD: |
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61 | System.out.println("Header field detected: " |
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62 | + stream.getField()); |
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63 | break; |
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64 | case MimeTokenStream.T_START_MULTIPART: |
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65 | System.out.println("Multipart message detexted," |
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66 | + " header data = " |
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67 | + stream.getBodyDescriptor()); |
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68 | ... |
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69 | } |
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70 | } |
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71 | -------------------------------------------------------------------- |
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72 | |
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73 | The token stream provides a set of tokens. Tokens are identified |
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74 | by a state. Most states are simply event indicators, with no |
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75 | additional data available. However, there are some states, |
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76 | which provide additional data. For example, the state |
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77 | <<<T_BODY>>>, which indicates that an actual body is available, |
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78 | If you note this state, then you may ask for the bodies contents, |
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79 | which are provided through the <<<getInputStream()>>> method, |
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80 | or you might ask for the header data by invoking |
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81 | <<<getBodyDescriptor()>>>. |
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82 | |
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83 | {Sample Token Stream} |
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84 | |
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85 | The following sample should give you a rough idea of the order, |
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86 | in which you'll receive tokens: |
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87 | |
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88 | -------------------------------------------------------------------- |
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89 | T_START_MESSAGE |
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90 | T_START_HEADER |
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91 | T_FIELD |
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92 | T_FIELD |
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93 | ... |
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94 | T_END_HEADER |
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95 | T_START_MULTIPART |
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96 | T_PREAMBLE |
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97 | T_START_BODYPART |
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98 | T_START_HEADER |
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99 | T_FIELD |
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100 | T_FIELD |
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101 | ... |
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102 | T_END_HEADER |
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103 | T_BODY |
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104 | T_END_BODYPART |
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105 | T_START_BODYPART |
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106 | T_START_HEADER |
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107 | T_FIELD |
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108 | T_FIELD |
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109 | ... |
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110 | T_END_HEADER |
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111 | T_BODY |
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112 | T_END_BODYPART |
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113 | T_EPILOGUE |
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114 | T_END_MULTIPART |
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115 | T_END_MESSAGE |
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116 | -------------------------------------------------------------------- |
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117 | |
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118 | The example shows a multipart message with two parts. |
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119 | |
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120 | {Event Handlers} |
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121 | |
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122 | The event based API requires, that you provide an event handler, |
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123 | which receives events. The event handler is an object, which |
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124 | implements the {{{apidocs/org/apache/james/mime4j/parser/ContentHandler.html} |
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125 | ContentHandler}} interface. Here's an example, how you could |
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126 | implement an event handler: |
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127 | |
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128 | -------------------------------------------------------------------- |
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129 | public class MyContentHandler extends org.apache.james.mime4j.parser.ContentHandler { |
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130 | public body(BodyDescriptor bd, InputStream is) |
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131 | throws MimeException, IOException { |
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132 | System.out.println("Body detected, contents = " |
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133 | + is + ", header data = " + bd); |
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134 | } |
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135 | public void field(String fieldData) throws MimeException { |
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136 | System.out.println("Header field detected: " |
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137 | + fieldData); |
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138 | } |
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139 | public void startMultipart(BodyDescriptor bd) throws MimeException { |
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140 | System.out.println("Multipart message detexted, header data = " |
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141 | + bd); |
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142 | } |
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143 | ... |
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144 | } |
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145 | -------------------------------------------------------------------- |
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146 | |
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147 | A little bit of additional code allows us to create an example, which |
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148 | is functionally equivalent to the example from the section on |
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149 | {{{#Token Streams}Token Streams}}: |
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150 | |
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151 | -------------------------------------------------------------------- |
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152 | ContentHandler handler = new MyContentHandler(); |
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153 | MimeStreamParser parser = new MimeStreamParser(); |
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154 | parser.setContentHandler(handler); |
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155 | parser.parse(new BufferedInputStream(new FileInputStream("mime.msg"))); |
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156 | -------------------------------------------------------------------- |
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157 | |
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158 | {Sample Event Stream} |
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159 | |
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160 | Like above for tokens, we provide an additional example, which |
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161 | demonstrates the typical order of events that you have to expect: |
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162 | |
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163 | -------------------------------------------------------------------- |
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164 | startMessage() |
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165 | startHeader() |
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166 | field(...) |
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167 | field(...) |
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168 | ... |
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169 | endHeader() |
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170 | startMultipart() |
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171 | preamble(...) |
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172 | startBodyPart() |
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173 | startHeader() |
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174 | field(...) |
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175 | field(...) |
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176 | ... |
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177 | endHeader() |
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178 | body() |
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179 | endBodyPart() |
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180 | startBodyPart() |
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181 | startHeader() |
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182 | field(...) |
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183 | field(...) |
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184 | ... |
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185 | endHeader() |
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186 | body() |
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187 | endBodyPart() |
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188 | epilogue(...) |
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189 | endMultipart() |
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190 | endMessage() |
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191 | -------------------------------------------------------------------- |
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