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.text.SimpleDateFormat;
23 import java.util.Date;
24 import java.util.Locale;
25 import java.util.TimeZone;
26
27 /**
28 * This class provides utilities for handling some semi-trivial HTTP stuff that
29 * would otherwise be handled elsewhere.
30 *
31 * @author <a href="mailto:magnus@handpoint.com">Magnús Þór Torfason</a>
32 * @version $Id: HttpUtils.java 1071052 2011-02-15 20:54:47Z tv $
33 */
34 public class HttpUtils
35 {
36 /**
37 * The date format to use for HTTP Dates.
38 */
39 private static SimpleDateFormat httpDateFormat;
40
41 static
42 {
43 httpDateFormat = new SimpleDateFormat(
44 "EEE, dd MMM yyyy HH:mm:ss z", Locale.US);
45 httpDateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
46 }
47
48 /**
49 * Formats a java Date according to rfc 1123, the rfc standard for dates in
50 * http.
51 *
52 * @param date The Date to format
53 * @return A String representation of the date
54 */
55 public static String formatHttpDate(Date date)
56 {
57 synchronized (httpDateFormat)
58 {
59 return httpDateFormat.format(date);
60 }
61 }
62
63 /**
64 * This method sets the required expiration headers in the response for a
65 * given RunData object. This method attempts to set all relevant headers,
66 * both for HTTP 1.0 and HTTP 1.1.
67 *
68 * @param data The RunData object we are setting cache information for.
69 * @param expiry The number of milliseconds until the document should expire,
70 * <code>0</code> indicating immediate expiration (i.e. no caching).
71 */
72 public static void setCacheHeaders(RunData data, int expiry)
73 {
74 if (0 == expiry)
75 {
76 data.getResponse().setHeader("Pragma", "no-cache");
77 data.getResponse().setHeader("Cache-Control", "no-cache");
78 data.getResponse().setDateHeader("Expires", System.currentTimeMillis());
79 }
80 else
81 {
82 data.getResponse().setDateHeader("Expires", System.currentTimeMillis() + expiry);
83 }
84 }
85 }