[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 filters; |
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| 19 | |
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| 20 | |
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| 21 | import java.io.IOException; |
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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 | |
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| 29 | |
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| 30 | /** |
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| 31 | * <p>Example filter that sets the character encoding to be used in parsing the |
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| 32 | * incoming request, either unconditionally or only if the client did not |
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| 33 | * specify a character encoding. Configuration of this filter is based on |
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| 34 | * the following initialization parameters:</p> |
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| 35 | * <ul> |
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| 36 | * <li><strong>encoding</strong> - The character encoding to be configured |
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| 37 | * for this request, either conditionally or unconditionally based on |
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| 38 | * the <code>ignore</code> initialization parameter. This parameter |
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| 39 | * is required, so there is no default.</li> |
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| 40 | * <li><strong>ignore</strong> - If set to "true", any character encoding |
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| 41 | * specified by the client is ignored, and the value returned by the |
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| 42 | * <code>selectEncoding()</code> method is set. If set to "false, |
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| 43 | * <code>selectEncoding()</code> is called <strong>only</strong> if the |
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| 44 | * client has not already specified an encoding. By default, this |
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| 45 | * parameter is set to "true".</li> |
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| 46 | * </ul> |
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| 47 | * |
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| 48 | * <p>Although this filter can be used unchanged, it is also easy to |
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| 49 | * subclass it and make the <code>selectEncoding()</code> method more |
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| 50 | * intelligent about what encoding to choose, based on characteristics of |
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| 51 | * the incoming request (such as the values of the <code>Accept-Language</code> |
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| 52 | * and <code>User-Agent</code> headers, or a value stashed in the current |
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| 53 | * user's session.</p> |
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| 54 | * |
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| 55 | * @author Craig McClanahan |
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| 56 | * @version $Revision: 500674 $ $Date: 2007-01-28 00:15:00 +0100 (Sun, 28 Jan 2007) $ |
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| 57 | */ |
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| 58 | |
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| 59 | public class SetCharacterEncodingFilter implements Filter { |
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| 60 | |
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| 61 | |
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| 62 | // ----------------------------------------------------- Instance Variables |
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| 63 | |
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| 64 | |
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| 65 | /** |
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| 66 | * The default character encoding to set for requests that pass through |
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| 67 | * this filter. |
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| 68 | */ |
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| 69 | protected String encoding = null; |
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| 70 | |
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| 71 | |
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| 72 | /** |
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| 73 | * The filter configuration object we are associated with. If this value |
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| 74 | * is null, this filter instance is not currently configured. |
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| 75 | */ |
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| 76 | protected FilterConfig filterConfig = null; |
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| 77 | |
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| 78 | |
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| 79 | /** |
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| 80 | * Should a character encoding specified by the client be ignored? |
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| 81 | */ |
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| 82 | protected boolean ignore = true; |
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| 83 | |
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| 84 | |
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| 85 | // --------------------------------------------------------- Public Methods |
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| 86 | |
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| 87 | |
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| 88 | /** |
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| 89 | * Take this filter out of service. |
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| 90 | */ |
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| 91 | public void destroy() { |
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| 92 | |
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| 93 | this.encoding = null; |
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| 94 | this.filterConfig = null; |
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| 95 | |
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| 96 | } |
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| 97 | |
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| 98 | |
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| 99 | /** |
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| 100 | * Select and set (if specified) the character encoding to be used to |
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| 101 | * interpret request parameters for this request. |
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| 102 | * |
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| 103 | * @param request The servlet request we are processing |
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| 104 | * @param result The servlet response we are creating |
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| 105 | * @param chain The filter chain we are processing |
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| 106 | * |
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| 107 | * @exception IOException if an input/output error occurs |
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| 108 | * @exception ServletException if a servlet error occurs |
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| 109 | */ |
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| 110 | public void doFilter(ServletRequest request, ServletResponse response, |
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| 111 | FilterChain chain) |
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| 112 | throws IOException, ServletException { |
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| 113 | |
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| 114 | // Conditionally select and set the character encoding to be used |
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| 115 | if (ignore || (request.getCharacterEncoding() == null)) { |
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| 116 | String encoding = selectEncoding(request); |
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| 117 | if (encoding != null) |
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| 118 | request.setCharacterEncoding(encoding); |
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| 119 | } |
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| 120 | |
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| 121 | // Pass control on to the next filter |
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| 122 | chain.doFilter(request, response); |
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| 123 | |
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| 124 | } |
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| 125 | |
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| 126 | |
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| 127 | /** |
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| 128 | * Place this filter into service. |
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| 129 | * |
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| 130 | * @param filterConfig The filter configuration object |
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| 131 | */ |
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| 132 | public void init(FilterConfig filterConfig) throws ServletException { |
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| 133 | |
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| 134 | this.filterConfig = filterConfig; |
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| 135 | this.encoding = filterConfig.getInitParameter("encoding"); |
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| 136 | String value = filterConfig.getInitParameter("ignore"); |
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| 137 | if (value == null) |
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| 138 | this.ignore = true; |
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| 139 | else if (value.equalsIgnoreCase("true")) |
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| 140 | this.ignore = true; |
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| 141 | else if (value.equalsIgnoreCase("yes")) |
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| 142 | this.ignore = true; |
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| 143 | else |
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| 144 | this.ignore = false; |
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| 145 | |
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| 146 | } |
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| 147 | |
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| 148 | |
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| 149 | // ------------------------------------------------------ Protected Methods |
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| 150 | |
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| 151 | |
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| 152 | /** |
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| 153 | * Select an appropriate character encoding to be used, based on the |
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| 154 | * characteristics of the current request and/or filter initialization |
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| 155 | * parameters. If no character encoding should be set, return |
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| 156 | * <code>null</code>. |
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| 157 | * <p> |
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| 158 | * The default implementation unconditionally returns the value configured |
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| 159 | * by the <strong>encoding</strong> initialization parameter for this |
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| 160 | * filter. |
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| 161 | * |
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| 162 | * @param request The servlet request we are processing |
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| 163 | */ |
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| 164 | protected String selectEncoding(ServletRequest request) { |
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| 165 | |
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| 166 | return (this.encoding); |
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| 167 | |
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| 168 | } |
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| 169 | |
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| 170 | |
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| 171 | } |
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