[66] | 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 | |
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| 18 | package compressionFilters; |
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| 19 | |
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| 20 | import java.io.IOException; |
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| 21 | import java.util.Enumeration; |
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| 22 | import javax.servlet.Filter; |
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| 23 | import javax.servlet.FilterChain; |
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| 24 | import javax.servlet.FilterConfig; |
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| 25 | import javax.servlet.ServletException; |
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| 26 | import javax.servlet.ServletRequest; |
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| 27 | import javax.servlet.ServletResponse; |
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| 28 | import javax.servlet.http.HttpServletRequest; |
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| 29 | import javax.servlet.http.HttpServletResponse; |
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| 30 | |
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| 31 | |
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| 32 | /** |
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| 33 | * Implementation of <code>javax.servlet.Filter</code> used to compress |
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| 34 | * the ServletResponse if it is bigger than a threshold. |
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| 35 | * |
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| 36 | * @author Amy Roh |
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| 37 | * @author Dmitri Valdin |
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| 38 | * @version $Revision: 467217 $, $Date: 2006-10-24 05:14:34 +0200 (Tue, 24 Oct 2006) $ |
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| 39 | */ |
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| 40 | |
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| 41 | public class CompressionFilter implements Filter{ |
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| 42 | |
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| 43 | /** |
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| 44 | * The filter configuration object we are associated with. If this value |
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| 45 | * is null, this filter instance is not currently configured. |
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| 46 | */ |
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| 47 | private FilterConfig config = null; |
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| 48 | |
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| 49 | /** |
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| 50 | * Minimal reasonable threshold |
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| 51 | */ |
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| 52 | private int minThreshold = 128; |
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| 53 | |
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| 54 | |
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| 55 | /** |
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| 56 | * The threshold number to compress |
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| 57 | */ |
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| 58 | protected int compressionThreshold; |
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| 59 | |
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| 60 | /** |
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| 61 | * Debug level for this filter |
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| 62 | */ |
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| 63 | private int debug = 0; |
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| 64 | |
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| 65 | /** |
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| 66 | * Place this filter into service. |
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| 67 | * |
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| 68 | * @param filterConfig The filter configuration object |
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| 69 | */ |
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| 70 | |
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| 71 | public void init(FilterConfig filterConfig) { |
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| 72 | |
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| 73 | config = filterConfig; |
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| 74 | if (filterConfig != null) { |
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| 75 | String value = filterConfig.getInitParameter("debug"); |
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| 76 | if (value!=null) { |
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| 77 | debug = Integer.parseInt(value); |
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| 78 | } else { |
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| 79 | debug = 0; |
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| 80 | } |
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| 81 | String str = filterConfig.getInitParameter("compressionThreshold"); |
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| 82 | if (str!=null) { |
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| 83 | compressionThreshold = Integer.parseInt(str); |
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| 84 | if (compressionThreshold != 0 && compressionThreshold < minThreshold) { |
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| 85 | if (debug > 0) { |
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| 86 | System.out.println("compressionThreshold should be either 0 - no compression or >= " + minThreshold); |
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| 87 | System.out.println("compressionThreshold set to " + minThreshold); |
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| 88 | } |
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| 89 | compressionThreshold = minThreshold; |
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| 90 | } |
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| 91 | } else { |
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| 92 | compressionThreshold = 0; |
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| 93 | } |
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| 94 | |
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| 95 | } else { |
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| 96 | compressionThreshold = 0; |
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| 97 | } |
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| 98 | |
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| 99 | } |
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| 100 | |
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| 101 | /** |
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| 102 | * Take this filter out of service. |
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| 103 | */ |
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| 104 | public void destroy() { |
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| 105 | |
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| 106 | this.config = null; |
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| 107 | |
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| 108 | } |
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| 109 | |
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| 110 | /** |
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| 111 | * The <code>doFilter</code> method of the Filter is called by the container |
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| 112 | * each time a request/response pair is passed through the chain due |
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| 113 | * to a client request for a resource at the end of the chain. |
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| 114 | * The FilterChain passed into this method allows the Filter to pass on the |
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| 115 | * request and response to the next entity in the chain.<p> |
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| 116 | * This method first examines the request to check whether the client support |
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| 117 | * compression. <br> |
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| 118 | * It simply just pass the request and response if there is no support for |
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| 119 | * compression.<br> |
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| 120 | * If the compression support is available, it creates a |
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| 121 | * CompressionServletResponseWrapper object which compresses the content and |
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| 122 | * modifies the header if the content length is big enough. |
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| 123 | * It then invokes the next entity in the chain using the FilterChain object |
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| 124 | * (<code>chain.doFilter()</code>), <br> |
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| 125 | **/ |
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| 126 | |
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| 127 | public void doFilter ( ServletRequest request, ServletResponse response, |
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| 128 | FilterChain chain ) throws IOException, ServletException { |
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| 129 | |
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| 130 | if (debug > 0) { |
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| 131 | System.out.println("@doFilter"); |
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| 132 | } |
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| 133 | |
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| 134 | if (compressionThreshold == 0) { |
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| 135 | if (debug > 0) { |
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| 136 | System.out.println("doFilter gets called, but compressionTreshold is set to 0 - no compression"); |
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| 137 | } |
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| 138 | chain.doFilter(request, response); |
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| 139 | return; |
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| 140 | } |
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| 141 | |
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| 142 | boolean supportCompression = false; |
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| 143 | if (request instanceof HttpServletRequest) { |
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| 144 | if (debug > 1) { |
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| 145 | System.out.println("requestURI = " + ((HttpServletRequest)request).getRequestURI()); |
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| 146 | } |
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| 147 | |
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| 148 | // Are we allowed to compress ? |
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| 149 | String s = (String) ((HttpServletRequest)request).getParameter("gzip"); |
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| 150 | if ("false".equals(s)) { |
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| 151 | if (debug > 0) { |
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| 152 | System.out.println("got parameter gzip=false --> don't compress, just chain filter"); |
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| 153 | } |
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| 154 | chain.doFilter(request, response); |
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| 155 | return; |
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| 156 | } |
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| 157 | |
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| 158 | Enumeration e = |
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| 159 | ((HttpServletRequest)request).getHeaders("Accept-Encoding"); |
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| 160 | while (e.hasMoreElements()) { |
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| 161 | String name = (String)e.nextElement(); |
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| 162 | if (name.indexOf("gzip") != -1) { |
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| 163 | if (debug > 0) { |
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| 164 | System.out.println("supports compression"); |
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| 165 | } |
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| 166 | supportCompression = true; |
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| 167 | } else { |
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| 168 | if (debug > 0) { |
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| 169 | System.out.println("no support for compresion"); |
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| 170 | } |
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| 171 | } |
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| 172 | } |
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| 173 | } |
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| 174 | |
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| 175 | if (!supportCompression) { |
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| 176 | if (debug > 0) { |
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| 177 | System.out.println("doFilter gets called wo compression"); |
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| 178 | } |
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| 179 | chain.doFilter(request, response); |
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| 180 | return; |
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| 181 | } else { |
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| 182 | if (response instanceof HttpServletResponse) { |
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| 183 | CompressionServletResponseWrapper wrappedResponse = |
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| 184 | new CompressionServletResponseWrapper((HttpServletResponse)response); |
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| 185 | wrappedResponse.setDebugLevel(debug); |
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| 186 | wrappedResponse.setCompressionThreshold(compressionThreshold); |
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| 187 | if (debug > 0) { |
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| 188 | System.out.println("doFilter gets called with compression"); |
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| 189 | } |
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| 190 | try { |
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| 191 | chain.doFilter(request, wrappedResponse); |
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| 192 | } finally { |
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| 193 | wrappedResponse.finishResponse(); |
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| 194 | } |
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| 195 | return; |
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| 196 | } |
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| 197 | } |
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| 198 | } |
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| 199 | |
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| 200 | /** |
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| 201 | * Set filter config |
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| 202 | * This function is equivalent to init. Required by Weblogic 6.1 |
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| 203 | * |
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| 204 | * @param filterConfig The filter configuration object |
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| 205 | */ |
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| 206 | public void setFilterConfig(FilterConfig filterConfig) { |
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| 207 | init(filterConfig); |
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| 208 | } |
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| 209 | |
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| 210 | /** |
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| 211 | * Return filter config |
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| 212 | * Required by Weblogic 6.1 |
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| 213 | */ |
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| 214 | public FilterConfig getFilterConfig() { |
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| 215 | return config; |
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| 216 | } |
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| 217 | |
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| 218 | } |
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| 219 | |
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