1 // ======================================================================== 2 // Copyright 2006 Mort Bay Consulting Pty. Ltd. 3 // ------------------------------------------------------------------------ 4 // Licensed under the Apache License, Version 2.0 (the "License"); 5 // you may not use this file except in compliance with the License. 6 // You may obtain a copy of the License at 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // Unless required by applicable law or agreed to in writing, software 9 // distributed under the License is distributed on an "AS IS" BASIS, 10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 11 // See the License for the specific language governing permissions and 12 // limitations under the License. 13 // ======================================================================== 14 15 package org.mortbay.servlet; 16 17 import java.io.IOException; 18 import java.util.HashMap; 19 import java.util.Map; 20 import java.util.regex.Matcher; 21 import java.util.regex.Pattern; 22 23 import javax.servlet.Filter; 24 import javax.servlet.FilterChain; 25 import javax.servlet.FilterConfig; 26 import javax.servlet.ServletException; 27 import javax.servlet.ServletRequest; 28 import javax.servlet.ServletResponse; 29 import javax.servlet.http.HttpServletRequest; 30 31 /* ------------------------------------------------------------ */ 32 /** User Agent Filter. 33 * <p> 34 * This filter allows efficient matching of user agent strings for 35 * downstream or extended filters to use for browser specific logic. 36 * </p> 37 * <p> 38 * The filter is configured with the following init parameters: 39 * <dl> 40 * <dt>attribute</dt><dd>If set, then the request attribute of this name is set with the matched user agent string</dd> 41 * <dt>cacheSize</dt><dd>The size of the user-agent cache, used to avoid reparsing of user agent strings. The entire cache is flushed 42 * when this size is reached</dd> 43 * <dt>userAgent</dt><dd>A regex {@link Pattern} to extract the essential elements of the user agent. 44 * The concatenation of matched pattern groups is used as the user agent name</dd> 45 * <dl> 46 * An example value for pattern is <code>(?:Mozilla[^\(]*\(compatible;\s*+([^;]*);.*)|(?:.*?([^\s]+/[^\s]+).*)</code>. These two 47 * pattern match the common compatibility user-agent strings and extract the real user agent, failing that, the first 48 * element of the agent string is returned. 49 * @author gregw 50 * 51 */ 52 public class UserAgentFilter implements Filter 53 { 54 private Pattern _pattern; 55 private Map _agentCache = new HashMap(); 56 private int _agentCacheSize=1024; 57 private String _attribute; 58 59 /* ------------------------------------------------------------ */ 60 /* (non-Javadoc) 61 * @see javax.servlet.Filter#destroy() 62 */ 63 public void destroy() 64 { 65 } 66 67 /* ------------------------------------------------------------ */ 68 /* (non-Javadoc) 69 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) 70 */ 71 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException 72 { 73 if (_attribute!=null && _pattern!=null) 74 { 75 String ua=getUserAgent(request); 76 request.setAttribute(_attribute,ua); 77 } 78 chain.doFilter(request,response); 79 } 80 81 /* ------------------------------------------------------------ */ 82 /* (non-Javadoc) 83 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig) 84 */ 85 public void init(FilterConfig filterConfig) throws ServletException 86 { 87 _attribute=filterConfig.getInitParameter("attribute"); 88 89 String p=filterConfig.getInitParameter("userAgent"); 90 if (p!=null) 91 _pattern=Pattern.compile(p); 92 93 String size=filterConfig.getInitParameter("cacheSize"); 94 if (size!=null) 95 _agentCacheSize=Integer.parseInt(size); 96 } 97 98 /* ------------------------------------------------------------ */ 99 public String getUserAgent(ServletRequest request) 100 { 101 String ua=((HttpServletRequest)request).getHeader("User-Agent"); 102 return getUserAgent(ua); 103 } 104 105 /* ------------------------------------------------------------ */ 106 /** Get UserAgent. 107 * The configured agent patterns are used to match against the passed user agent string. 108 * If any patterns match, the concatenation of pattern groups is returned as the user agent 109 * string. Match results are cached. 110 * @param ua A user agent string 111 * @return The matched pattern groups or the original user agent string 112 */ 113 public String getUserAgent(String ua) 114 { 115 if (ua==null) 116 return null; 117 118 String tag; 119 synchronized(_agentCache) 120 { 121 tag = (String)_agentCache.get(ua); 122 } 123 124 if (tag==null) 125 { 126 Matcher matcher=_pattern.matcher(ua); 127 if (matcher.matches()) 128 { 129 if(matcher.groupCount()>0) 130 { 131 for (int g=1;g<=matcher.groupCount();g++) 132 { 133 String group=matcher.group(g); 134 if (group!=null) 135 tag=tag==null?group:(tag+group); 136 } 137 } 138 else 139 tag=matcher.group(); 140 } 141 else 142 tag=ua; 143 144 synchronized(_agentCache) 145 { 146 if (_agentCache.size()>=_agentCacheSize) 147 _agentCache.clear(); 148 _agentCache.put(ua,tag); 149 } 150 151 } 152 return tag; 153 } 154 }