1 package org.apache.turbine.util;
2
3 /*
4 * Licensed to the Apache Software Foundation (ASF) under one
5 * or more contributor license agreements. See the NOTICE file
6 * distributed with this work for additional information
7 * regarding copyright ownership. The ASF licenses this file
8 * to you under the Apache License, Version 2.0 (the
9 * "License"); you may not use this file except in compliance
10 * with the License. You may obtain a copy of the License at
11 *
12 * http://www.apache.org/licenses/LICENSE-2.0
13 *
14 * Unless required by applicable law or agreed to in writing,
15 * software distributed under the License is distributed on an
16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17 * KIND, either express or implied. See the License for the
18 * specific language governing permissions and limitations
19 * under the License.
20 */
21
22 import java.util.Date;
23 import java.util.Locale;
24 import java.util.TimeZone;
25
26 import javax.servlet.http.HttpServletResponse;
27
28 import org.apache.commons.lang3.time.FastDateFormat;
29 import org.apache.turbine.Turbine;
30 import org.apache.turbine.pipeline.PipelineData;
31
32 /**
33 * This class provides utilities for handling some semi-trivial HTTP stuff that
34 * would otherwise be handled elsewhere.
35 *
36 * @author <a href="mailto:magnus@handpoint.com">Magnús Þór Torfason</a>
37 * @version $Id$
38 */
39 public class HttpUtils
40 {
41 /**
42 * The date format to use for HTTP Dates.
43 */
44 private static FastDateFormat httpDateFormat = FastDateFormat.getInstance(
45 "EEE, dd MMM yyyy HH:mm:ss z",
46 TimeZone.getTimeZone("GMT"),
47 Locale.US);
48
49 /**
50 * Formats a java Date according to rfc 1123, the rfc standard for dates in
51 * http.
52 *
53 * @param date The Date to format
54 * @return A String representation of the date
55 */
56 public static String formatHttpDate(Date date)
57 {
58 return httpDateFormat.format(date);
59 }
60
61 /**
62 * This method sets the required expiration headers in the response for a
63 * given {@link PipelineData} object. This method attempts to set all relevant headers,
64 * both for HTTP 1.0 and HTTP 1.1.
65 *
66 * @param pipelineData The {@link PipelineData} object we are setting cache information for.
67 * @param expiry The number of milliseconds until the document should expire,
68 * <code>0</code> indicating immediate expiration (i.e. no caching).
69 */
70 public static void setCacheHeaders(PipelineData pipelineData, int expiry)
71 {
72 HttpServletResponse response = pipelineData.get(Turbine.class, HttpServletResponse.class);
73
74 if (0 == expiry)
75 {
76 response.setHeader("Pragma", "no-cache");
77 response.setHeader("Cache-Control", "no-cache");
78 response.setDateHeader("Expires", System.currentTimeMillis());
79 }
80 else
81 {
82 response.setDateHeader("Expires", System.currentTimeMillis() + expiry);
83 }
84 }
85 }