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.ArrayList; 19 import java.util.Enumeration; 20 import java.util.HashMap; 21 import java.util.List; 22 import java.util.Map; 23 import java.util.regex.Matcher; 24 import java.util.regex.Pattern; 25 26 import javax.servlet.Filter; 27 import javax.servlet.FilterChain; 28 import javax.servlet.FilterConfig; 29 import javax.servlet.ServletException; 30 import javax.servlet.ServletRequest; 31 import javax.servlet.ServletResponse; 32 import javax.servlet.http.HttpServletRequest; 33 34 /* ------------------------------------------------------------ */ 35 /** User Agent Filter. 36 * <p> 37 * This filter allows efficient matching of user agent strings for 38 * downstream or extended filters to use for browser specific logic. 39 * </p> 40 * <p> 41 * The filter is configured with the following init parameters: 42 * <dl> 43 * <dt>attribute</dt><dd>If set, then the request attribute of this name is set with the matched user agent string</dd> 44 * <dt>cacheSize</dt><dd>The size of the user-agent cache, used to avoid reparsing of user agent strings. The entire cache is flushed 45 * when this size is reached</dd> 46 * <dt>userAgent</dt><dd>A regex {@link Pattern} to extract the essential elements of the user agent. 47 * The concatenation of matched pattern groups is used as the user agent name</dd> 48 * <dl> 49 * An example value for pattern is <code>(?:Mozilla[^\(]*\(compatible;\s*+([^;]*);.*)|(?:.*?([^\s]+/[^\s]+).*)</code>. These two 50 * pattern match the common compatibility user-agent strings and extract the real user agent, failing that, the first 51 * element of the agent string is returned. 52 * @author gregw 53 * 54 */ 55 public class UserAgentFilter implements Filter 56 { 57 private Pattern _pattern; 58 private Map _agentCache = new HashMap(); 59 private int _agentCacheSize=1024; 60 private String _attribute; 61 62 /* ------------------------------------------------------------ */ 63 /* (non-Javadoc) 64 * @see javax.servlet.Filter#destroy() 65 */ 66 public void destroy() 67 { 68 } 69 70 /* ------------------------------------------------------------ */ 71 /* (non-Javadoc) 72 * @see javax.servlet.Filter#doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain) 73 */ 74 public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException 75 { 76 if (_attribute!=null && _pattern!=null) 77 { 78 String ua=getUserAgent(request); 79 request.setAttribute(_attribute,ua); 80 } 81 chain.doFilter(request,response); 82 } 83 84 /* ------------------------------------------------------------ */ 85 /* (non-Javadoc) 86 * @see javax.servlet.Filter#init(javax.servlet.FilterConfig) 87 */ 88 public void init(FilterConfig filterConfig) throws ServletException 89 { 90 _attribute=filterConfig.getInitParameter("attribute"); 91 92 String p=filterConfig.getInitParameter("userAgent"); 93 if (p!=null) 94 _pattern=Pattern.compile(p); 95 96 String size=filterConfig.getInitParameter("cacheSize"); 97 if (size!=null) 98 _agentCacheSize=Integer.parseInt(size); 99 } 100 101 /* ------------------------------------------------------------ */ 102 public String getUserAgent(ServletRequest request) 103 { 104 String ua=((HttpServletRequest)request).getHeader("User-Agent"); 105 return getUserAgent(ua); 106 } 107 108 /* ------------------------------------------------------------ */ 109 /** Get UserAgent. 110 * The configured agent patterns are used to match against the passed user agent string. 111 * If any patterns match, the concatenation of pattern groups is returned as the user agent 112 * string. Match results are cached. 113 * @param ua A user agent string 114 * @return The matched pattern groups or the original user agent string 115 */ 116 public String getUserAgent(String ua) 117 { 118 if (ua==null) 119 return null; 120 121 String tag; 122 synchronized(_agentCache) 123 { 124 tag = (String)_agentCache.get(ua); 125 } 126 127 if (tag==null) 128 { 129 Matcher matcher=_pattern.matcher(ua); 130 if (matcher.matches()) 131 { 132 if(matcher.groupCount()>0) 133 { 134 for (int g=1;g<=matcher.groupCount();g++) 135 { 136 String group=matcher.group(g); 137 if (group!=null) 138 tag=tag==null?group:(tag+group); 139 } 140 } 141 else 142 tag=matcher.group(); 143 } 144 else 145 tag=ua; 146 147 synchronized(_agentCache) 148 { 149 if (_agentCache.size()>=_agentCacheSize) 150 _agentCache.clear(); 151 _agentCache.put(ua,tag); 152 } 153 154 } 155 return tag; 156 } 157 }