[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 | * Example filter that can be attached to either an individual servlet |
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| 32 | * or to a URL pattern. This filter performs the following functions: |
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| 33 | * <ul> |
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| 34 | * <li>Attaches itself as a request attribute, under the attribute name |
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| 35 | * defined by the value of the <code>attribute</code> initialization |
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| 36 | * parameter.</li> |
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| 37 | * <li>Calculates the number of milliseconds required to perform the |
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| 38 | * servlet processing required by this request, including any |
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| 39 | * subsequently defined filters, and logs the result to the servlet |
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| 40 | * context log for this application. |
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| 41 | * </ul> |
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| 42 | * |
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| 43 | * @author Craig McClanahan |
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| 44 | * @version $Revision: 500674 $ $Date: 2007-01-28 00:15:00 +0100 (Sun, 28 Jan 2007) $ |
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| 45 | */ |
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| 46 | |
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| 47 | public final class ExampleFilter implements Filter { |
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| 48 | |
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| 49 | |
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| 50 | // ----------------------------------------------------- Instance Variables |
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| 51 | |
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| 52 | |
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| 53 | /** |
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| 54 | * The request attribute name under which we store a reference to ourself. |
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| 55 | */ |
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| 56 | private String attribute = null; |
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| 57 | |
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| 58 | |
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| 59 | /** |
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| 60 | * The filter configuration object we are associated with. If this value |
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| 61 | * is null, this filter instance is not currently configured. |
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| 62 | */ |
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| 63 | private FilterConfig filterConfig = null; |
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| 64 | |
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| 65 | |
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| 66 | // --------------------------------------------------------- Public Methods |
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| 67 | |
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| 68 | |
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| 69 | /** |
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| 70 | * Take this filter out of service. |
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| 71 | */ |
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| 72 | public void destroy() { |
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| 73 | |
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| 74 | this.attribute = null; |
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| 75 | this.filterConfig = null; |
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| 76 | |
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| 77 | } |
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| 78 | |
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| 79 | |
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| 80 | /** |
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| 81 | * Time the processing that is performed by all subsequent filters in the |
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| 82 | * current filter stack, including the ultimately invoked servlet. |
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| 83 | * |
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| 84 | * @param request The servlet request we are processing |
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| 85 | * @param result The servlet response we are creating |
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| 86 | * @param chain The filter chain we are processing |
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| 87 | * |
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| 88 | * @exception IOException if an input/output error occurs |
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| 89 | * @exception ServletException if a servlet error occurs |
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| 90 | */ |
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| 91 | public void doFilter(ServletRequest request, ServletResponse response, |
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| 92 | FilterChain chain) |
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| 93 | throws IOException, ServletException { |
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| 94 | |
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| 95 | // Store ourselves as a request attribute (if requested) |
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| 96 | if (attribute != null) |
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| 97 | request.setAttribute(attribute, this); |
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| 98 | |
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| 99 | // Time and log the subsequent processing |
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| 100 | long startTime = System.currentTimeMillis(); |
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| 101 | chain.doFilter(request, response); |
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| 102 | long stopTime = System.currentTimeMillis(); |
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| 103 | filterConfig.getServletContext().log |
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| 104 | (this.toString() + ": " + (stopTime - startTime) + |
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| 105 | " milliseconds"); |
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| 106 | |
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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 | * Place this filter into service. |
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| 112 | * |
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| 113 | * @param filterConfig The filter configuration object |
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| 114 | */ |
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| 115 | public void init(FilterConfig filterConfig) throws ServletException { |
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| 116 | |
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| 117 | this.filterConfig = filterConfig; |
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| 118 | this.attribute = filterConfig.getInitParameter("attribute"); |
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| 119 | |
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| 120 | } |
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| 121 | |
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| 122 | |
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| 123 | /** |
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| 124 | * Return a String representation of this object. |
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| 125 | */ |
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| 126 | public String toString() { |
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| 127 | |
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| 128 | if (filterConfig == null) |
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| 129 | return ("InvokerFilter()"); |
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| 130 | StringBuffer sb = new StringBuffer("InvokerFilter("); |
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| 131 | sb.append(filterConfig); |
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| 132 | sb.append(")"); |
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| 133 | return (sb.toString()); |
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| 134 | |
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| 135 | } |
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| 136 | |
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| 137 | |
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| 138 | } |
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| 139 | |
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