1 | /* |
---|
2 | * Licensed to the Apache Software Foundation (ASF) under one or more |
---|
3 | * contributor license agreements. See the NOTICE file distributed with |
---|
4 | * this work for additional information regarding copyright ownership. |
---|
5 | * The ASF licenses this file to You under the Apache License, Version 2.0 |
---|
6 | * (the "License"); you may not use this file except in compliance with |
---|
7 | * the License. You may obtain a copy of the License at |
---|
8 | * |
---|
9 | * http://www.apache.org/licenses/LICENSE-2.0 |
---|
10 | * |
---|
11 | * Unless required by applicable law or agreed to in writing, software |
---|
12 | * distributed under the License is distributed on an "AS IS" BASIS, |
---|
13 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
---|
14 | * See the License for the specific language governing permissions and |
---|
15 | * limitations under the License. |
---|
16 | */ |
---|
17 | |
---|
18 | package compressionFilters; |
---|
19 | |
---|
20 | import java.io.IOException; |
---|
21 | import java.util.Enumeration; |
---|
22 | import javax.servlet.Filter; |
---|
23 | import javax.servlet.FilterChain; |
---|
24 | import javax.servlet.FilterConfig; |
---|
25 | import javax.servlet.ServletException; |
---|
26 | import javax.servlet.ServletRequest; |
---|
27 | import javax.servlet.ServletResponse; |
---|
28 | import javax.servlet.http.HttpServletRequest; |
---|
29 | import javax.servlet.http.HttpServletResponse; |
---|
30 | |
---|
31 | |
---|
32 | /** |
---|
33 | * Implementation of <code>javax.servlet.Filter</code> used to compress |
---|
34 | * the ServletResponse if it is bigger than a threshold. |
---|
35 | * |
---|
36 | * @author Amy Roh |
---|
37 | * @author Dmitri Valdin |
---|
38 | * @version $Revision: 467217 $, $Date: 2006-10-24 05:14:34 +0200 (Tue, 24 Oct 2006) $ |
---|
39 | */ |
---|
40 | |
---|
41 | public class CompressionFilter implements Filter{ |
---|
42 | |
---|
43 | /** |
---|
44 | * The filter configuration object we are associated with. If this value |
---|
45 | * is null, this filter instance is not currently configured. |
---|
46 | */ |
---|
47 | private FilterConfig config = null; |
---|
48 | |
---|
49 | /** |
---|
50 | * Minimal reasonable threshold |
---|
51 | */ |
---|
52 | private int minThreshold = 128; |
---|
53 | |
---|
54 | |
---|
55 | /** |
---|
56 | * The threshold number to compress |
---|
57 | */ |
---|
58 | protected int compressionThreshold; |
---|
59 | |
---|
60 | /** |
---|
61 | * Debug level for this filter |
---|
62 | */ |
---|
63 | private int debug = 0; |
---|
64 | |
---|
65 | /** |
---|
66 | * Place this filter into service. |
---|
67 | * |
---|
68 | * @param filterConfig The filter configuration object |
---|
69 | */ |
---|
70 | |
---|
71 | public void init(FilterConfig filterConfig) { |
---|
72 | |
---|
73 | config = filterConfig; |
---|
74 | if (filterConfig != null) { |
---|
75 | String value = filterConfig.getInitParameter("debug"); |
---|
76 | if (value!=null) { |
---|
77 | debug = Integer.parseInt(value); |
---|
78 | } else { |
---|
79 | debug = 0; |
---|
80 | } |
---|
81 | String str = filterConfig.getInitParameter("compressionThreshold"); |
---|
82 | if (str!=null) { |
---|
83 | compressionThreshold = Integer.parseInt(str); |
---|
84 | if (compressionThreshold != 0 && compressionThreshold < minThreshold) { |
---|
85 | if (debug > 0) { |
---|
86 | System.out.println("compressionThreshold should be either 0 - no compression or >= " + minThreshold); |
---|
87 | System.out.println("compressionThreshold set to " + minThreshold); |
---|
88 | } |
---|
89 | compressionThreshold = minThreshold; |
---|
90 | } |
---|
91 | } else { |
---|
92 | compressionThreshold = 0; |
---|
93 | } |
---|
94 | |
---|
95 | } else { |
---|
96 | compressionThreshold = 0; |
---|
97 | } |
---|
98 | |
---|
99 | } |
---|
100 | |
---|
101 | /** |
---|
102 | * Take this filter out of service. |
---|
103 | */ |
---|
104 | public void destroy() { |
---|
105 | |
---|
106 | this.config = null; |
---|
107 | |
---|
108 | } |
---|
109 | |
---|
110 | /** |
---|
111 | * The <code>doFilter</code> method of the Filter is called by the container |
---|
112 | * each time a request/response pair is passed through the chain due |
---|
113 | * to a client request for a resource at the end of the chain. |
---|
114 | * The FilterChain passed into this method allows the Filter to pass on the |
---|
115 | * request and response to the next entity in the chain.<p> |
---|
116 | * This method first examines the request to check whether the client support |
---|
117 | * compression. <br> |
---|
118 | * It simply just pass the request and response if there is no support for |
---|
119 | * compression.<br> |
---|
120 | * If the compression support is available, it creates a |
---|
121 | * CompressionServletResponseWrapper object which compresses the content and |
---|
122 | * modifies the header if the content length is big enough. |
---|
123 | * It then invokes the next entity in the chain using the FilterChain object |
---|
124 | * (<code>chain.doFilter()</code>), <br> |
---|
125 | **/ |
---|
126 | |
---|
127 | public void doFilter ( ServletRequest request, ServletResponse response, |
---|
128 | FilterChain chain ) throws IOException, ServletException { |
---|
129 | |
---|
130 | if (debug > 0) { |
---|
131 | System.out.println("@doFilter"); |
---|
132 | } |
---|
133 | |
---|
134 | if (compressionThreshold == 0) { |
---|
135 | if (debug > 0) { |
---|
136 | System.out.println("doFilter gets called, but compressionTreshold is set to 0 - no compression"); |
---|
137 | } |
---|
138 | chain.doFilter(request, response); |
---|
139 | return; |
---|
140 | } |
---|
141 | |
---|
142 | boolean supportCompression = false; |
---|
143 | if (request instanceof HttpServletRequest) { |
---|
144 | if (debug > 1) { |
---|
145 | System.out.println("requestURI = " + ((HttpServletRequest)request).getRequestURI()); |
---|
146 | } |
---|
147 | |
---|
148 | // Are we allowed to compress ? |
---|
149 | String s = (String) ((HttpServletRequest)request).getParameter("gzip"); |
---|
150 | if ("false".equals(s)) { |
---|
151 | if (debug > 0) { |
---|
152 | System.out.println("got parameter gzip=false --> don't compress, just chain filter"); |
---|
153 | } |
---|
154 | chain.doFilter(request, response); |
---|
155 | return; |
---|
156 | } |
---|
157 | |
---|
158 | Enumeration e = |
---|
159 | ((HttpServletRequest)request).getHeaders("Accept-Encoding"); |
---|
160 | while (e.hasMoreElements()) { |
---|
161 | String name = (String)e.nextElement(); |
---|
162 | if (name.indexOf("gzip") != -1) { |
---|
163 | if (debug > 0) { |
---|
164 | System.out.println("supports compression"); |
---|
165 | } |
---|
166 | supportCompression = true; |
---|
167 | } else { |
---|
168 | if (debug > 0) { |
---|
169 | System.out.println("no support for compresion"); |
---|
170 | } |
---|
171 | } |
---|
172 | } |
---|
173 | } |
---|
174 | |
---|
175 | if (!supportCompression) { |
---|
176 | if (debug > 0) { |
---|
177 | System.out.println("doFilter gets called wo compression"); |
---|
178 | } |
---|
179 | chain.doFilter(request, response); |
---|
180 | return; |
---|
181 | } else { |
---|
182 | if (response instanceof HttpServletResponse) { |
---|
183 | CompressionServletResponseWrapper wrappedResponse = |
---|
184 | new CompressionServletResponseWrapper((HttpServletResponse)response); |
---|
185 | wrappedResponse.setDebugLevel(debug); |
---|
186 | wrappedResponse.setCompressionThreshold(compressionThreshold); |
---|
187 | if (debug > 0) { |
---|
188 | System.out.println("doFilter gets called with compression"); |
---|
189 | } |
---|
190 | try { |
---|
191 | chain.doFilter(request, wrappedResponse); |
---|
192 | } finally { |
---|
193 | wrappedResponse.finishResponse(); |
---|
194 | } |
---|
195 | return; |
---|
196 | } |
---|
197 | } |
---|
198 | } |
---|
199 | |
---|
200 | /** |
---|
201 | * Set filter config |
---|
202 | * This function is equivalent to init. Required by Weblogic 6.1 |
---|
203 | * |
---|
204 | * @param filterConfig The filter configuration object |
---|
205 | */ |
---|
206 | public void setFilterConfig(FilterConfig filterConfig) { |
---|
207 | init(filterConfig); |
---|
208 | } |
---|
209 | |
---|
210 | /** |
---|
211 | * Return filter config |
---|
212 | * Required by Weblogic 6.1 |
---|
213 | */ |
---|
214 | public FilterConfig getFilterConfig() { |
---|
215 | return config; |
---|
216 | } |
---|
217 | |
---|
218 | } |
---|
219 | |
---|