1 | /* |
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2 | * Licensed to the Apache Software Foundation (ASF) under one or more |
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3 | * contributor license agreements. See the NOTICE file distributed with |
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4 | * this work for additional information regarding copyright ownership. |
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5 | * The ASF licenses this file to You under the Apache License, Version 2.0 |
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6 | * (the "License"); you may not use this file except in compliance with |
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7 | * the License. You may obtain a copy of the License at |
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8 | * |
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9 | * http://www.apache.org/licenses/LICENSE-2.0 |
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10 | * |
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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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13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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14 | * See the License for the specific language governing permissions and |
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15 | * limitations under the License. |
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16 | */ |
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17 | package compressionFilters; |
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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.util.zip.GZIPOutputStream; |
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22 | import javax.servlet.ServletOutputStream; |
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23 | import javax.servlet.http.HttpServletResponse; |
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24 | |
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25 | |
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26 | /** |
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27 | * Implementation of <b>ServletOutputStream</b> that works with |
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28 | * the CompressionServletResponseWrapper implementation. |
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29 | * |
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30 | * @author Amy Roh |
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31 | * @author Dmitri Valdin |
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32 | * @version $Revision: 500668 $, $Date: 2007-01-28 00:07:51 +0100 (Sun, 28 Jan 2007) $ |
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33 | */ |
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34 | |
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35 | public class CompressionResponseStream |
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36 | extends ServletOutputStream { |
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37 | |
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38 | |
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39 | // ----------------------------------------------------------- Constructors |
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40 | |
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41 | |
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42 | /** |
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43 | * Construct a servlet output stream associated with the specified Response. |
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44 | * |
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45 | * @param response The associated response |
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46 | */ |
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47 | public CompressionResponseStream(HttpServletResponse response) throws IOException{ |
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48 | |
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49 | super(); |
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50 | closed = false; |
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51 | this.response = response; |
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52 | this.output = response.getOutputStream(); |
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53 | |
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54 | } |
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55 | |
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56 | |
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57 | // ----------------------------------------------------- Instance Variables |
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58 | |
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59 | |
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60 | /** |
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61 | * The threshold number which decides to compress or not. |
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62 | * Users can configure in web.xml to set it to fit their needs. |
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63 | */ |
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64 | protected int compressionThreshold = 0; |
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65 | |
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66 | /** |
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67 | * Debug level |
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68 | */ |
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69 | private int debug = 0; |
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70 | |
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71 | /** |
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72 | * The buffer through which all of our output bytes are passed. |
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73 | */ |
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74 | protected byte[] buffer = null; |
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75 | |
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76 | /** |
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77 | * The number of data bytes currently in the buffer. |
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78 | */ |
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79 | protected int bufferCount = 0; |
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80 | |
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81 | /** |
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82 | * The underlying gzip output stream to which we should write data. |
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83 | */ |
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84 | protected OutputStream gzipstream = null; |
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85 | |
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86 | /** |
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87 | * Has this stream been closed? |
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88 | */ |
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89 | protected boolean closed = false; |
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90 | |
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91 | /** |
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92 | * The content length past which we will not write, or -1 if there is |
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93 | * no defined content length. |
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94 | */ |
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95 | protected int length = -1; |
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96 | |
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97 | /** |
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98 | * The response with which this servlet output stream is associated. |
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99 | */ |
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100 | protected HttpServletResponse response = null; |
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101 | |
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102 | /** |
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103 | * The underlying servket output stream to which we should write data. |
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104 | */ |
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105 | protected ServletOutputStream output = null; |
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106 | |
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107 | |
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108 | // --------------------------------------------------------- Public Methods |
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109 | |
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110 | /** |
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111 | * Set debug level |
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112 | */ |
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113 | public void setDebugLevel(int debug) { |
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114 | this.debug = debug; |
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115 | } |
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116 | |
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117 | |
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118 | /** |
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119 | * Set the compressionThreshold number and create buffer for this size |
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120 | */ |
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121 | protected void setBuffer(int threshold) { |
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122 | compressionThreshold = threshold; |
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123 | buffer = new byte[compressionThreshold]; |
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124 | if (debug > 1) { |
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125 | System.out.println("buffer is set to "+compressionThreshold); |
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126 | } |
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127 | } |
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128 | |
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129 | /** |
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130 | * Close this output stream, causing any buffered data to be flushed and |
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131 | * any further output data to throw an IOException. |
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132 | */ |
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133 | public void close() throws IOException { |
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134 | |
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135 | if (debug > 1) { |
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136 | System.out.println("close() @ CompressionResponseStream"); |
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137 | } |
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138 | if (closed) |
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139 | throw new IOException("This output stream has already been closed"); |
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140 | |
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141 | if (gzipstream != null) { |
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142 | flushToGZip(); |
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143 | gzipstream.close(); |
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144 | gzipstream = null; |
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145 | } else { |
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146 | if (bufferCount > 0) { |
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147 | if (debug > 2) { |
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148 | System.out.print("output.write("); |
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149 | System.out.write(buffer, 0, bufferCount); |
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150 | System.out.println(")"); |
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151 | } |
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152 | output.write(buffer, 0, bufferCount); |
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153 | bufferCount = 0; |
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154 | } |
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155 | } |
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156 | |
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157 | output.close(); |
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158 | closed = true; |
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159 | |
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160 | } |
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161 | |
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162 | |
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163 | /** |
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164 | * Flush any buffered data for this output stream, which also causes the |
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165 | * response to be committed. |
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166 | */ |
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167 | public void flush() throws IOException { |
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168 | |
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169 | if (debug > 1) { |
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170 | System.out.println("flush() @ CompressionResponseStream"); |
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171 | } |
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172 | if (closed) { |
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173 | throw new IOException("Cannot flush a closed output stream"); |
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174 | } |
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175 | |
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176 | if (gzipstream != null) { |
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177 | gzipstream.flush(); |
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178 | } |
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179 | |
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180 | } |
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181 | |
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182 | public void flushToGZip() throws IOException { |
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183 | |
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184 | if (debug > 1) { |
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185 | System.out.println("flushToGZip() @ CompressionResponseStream"); |
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186 | } |
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187 | if (bufferCount > 0) { |
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188 | if (debug > 1) { |
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189 | System.out.println("flushing out to GZipStream, bufferCount = " + bufferCount); |
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190 | } |
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191 | writeToGZip(buffer, 0, bufferCount); |
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192 | bufferCount = 0; |
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193 | } |
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194 | |
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195 | } |
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196 | |
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197 | /** |
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198 | * Write the specified byte to our output stream. |
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199 | * |
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200 | * @param b The byte to be written |
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201 | * |
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202 | * @exception IOException if an input/output error occurs |
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203 | */ |
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204 | public void write(int b) throws IOException { |
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205 | |
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206 | if (debug > 1) { |
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207 | System.out.println("write "+b+" in CompressionResponseStream "); |
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208 | } |
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209 | if (closed) |
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210 | throw new IOException("Cannot write to a closed output stream"); |
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211 | |
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212 | if (bufferCount >= buffer.length) { |
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213 | flushToGZip(); |
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214 | } |
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215 | |
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216 | buffer[bufferCount++] = (byte) b; |
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217 | |
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218 | } |
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219 | |
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220 | |
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221 | /** |
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222 | * Write <code>b.length</code> bytes from the specified byte array |
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223 | * to our output stream. |
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224 | * |
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225 | * @param b The byte array to be written |
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226 | * |
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227 | * @exception IOException if an input/output error occurs |
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228 | */ |
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229 | public void write(byte b[]) throws IOException { |
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230 | |
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231 | write(b, 0, b.length); |
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232 | |
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233 | } |
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234 | |
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235 | |
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236 | /** |
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237 | * Write <code>len</code> bytes from the specified byte array, starting |
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238 | * at the specified offset, to our output stream. |
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239 | * |
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240 | * @param b The byte array containing the bytes to be written |
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241 | * @param off Zero-relative starting offset of the bytes to be written |
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242 | * @param len The number of bytes to be written |
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243 | * |
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244 | * @exception IOException if an input/output error occurs |
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245 | */ |
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246 | public void write(byte b[], int off, int len) throws IOException { |
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247 | |
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248 | if (debug > 1) { |
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249 | System.out.println("write, bufferCount = " + bufferCount + " len = " + len + " off = " + off); |
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250 | } |
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251 | if (debug > 2) { |
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252 | System.out.print("write("); |
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253 | System.out.write(b, off, len); |
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254 | System.out.println(")"); |
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255 | } |
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256 | |
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257 | if (closed) |
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258 | throw new IOException("Cannot write to a closed output stream"); |
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259 | |
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260 | if (len == 0) |
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261 | return; |
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262 | |
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263 | // Can we write into buffer ? |
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264 | if (len <= (buffer.length - bufferCount)) { |
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265 | System.arraycopy(b, off, buffer, bufferCount, len); |
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266 | bufferCount += len; |
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267 | return; |
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268 | } |
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269 | |
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270 | // There is not enough space in buffer. Flush it ... |
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271 | flushToGZip(); |
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272 | |
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273 | // ... and try again. Note, that bufferCount = 0 here ! |
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274 | if (len <= (buffer.length - bufferCount)) { |
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275 | System.arraycopy(b, off, buffer, bufferCount, len); |
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276 | bufferCount += len; |
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277 | return; |
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278 | } |
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279 | |
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280 | // write direct to gzip |
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281 | writeToGZip(b, off, len); |
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282 | } |
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283 | |
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284 | public void writeToGZip(byte b[], int off, int len) throws IOException { |
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285 | |
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286 | if (debug > 1) { |
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287 | System.out.println("writeToGZip, len = " + len); |
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288 | } |
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289 | if (debug > 2) { |
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290 | System.out.print("writeToGZip("); |
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291 | System.out.write(b, off, len); |
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292 | System.out.println(")"); |
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293 | } |
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294 | if (gzipstream == null) { |
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295 | if (debug > 1) { |
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296 | System.out.println("new GZIPOutputStream"); |
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297 | } |
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298 | if (response.isCommitted()) { |
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299 | if (debug > 1) |
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300 | System.out.print("Response already committed. Using original output stream"); |
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301 | gzipstream = output; |
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302 | } else { |
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303 | response.addHeader("Content-Encoding", "gzip"); |
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304 | gzipstream = new GZIPOutputStream(output); |
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305 | } |
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306 | } |
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307 | gzipstream.write(b, off, len); |
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308 | |
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309 | } |
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310 | |
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311 | |
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312 | // -------------------------------------------------------- Package Methods |
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313 | |
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314 | |
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315 | /** |
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316 | * Has this response stream been closed? |
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317 | */ |
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318 | public boolean closed() { |
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319 | |
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320 | return (this.closed); |
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321 | |
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322 | } |
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323 | |
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324 | } |
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