001 package org.apache.turbine.util;
002
003 /*
004 * Licensed to the Apache Software Foundation (ASF) under one
005 * or more contributor license agreements. See the NOTICE file
006 * distributed with this work for additional information
007 * regarding copyright ownership. The ASF licenses this file
008 * to you under the Apache License, Version 2.0 (the
009 * "License"); you may not use this file except in compliance
010 * with the License. You may obtain a copy of the License at
011 *
012 * http://www.apache.org/licenses/LICENSE-2.0
013 *
014 * Unless required by applicable law or agreed to in writing,
015 * software distributed under the License is distributed on an
016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
017 * KIND, either express or implied. See the License for the
018 * specific language governing permissions and limitations
019 * under the License.
020 */
021
022 import java.text.SimpleDateFormat;
023 import java.util.Date;
024 import java.util.Locale;
025 import java.util.TimeZone;
026
027 /**
028 * This class provides utilities for handling some semi-trivial HTTP stuff that
029 * would otherwise be handled elsewhere.
030 *
031 * @author <a href="mailto:magnus@handpoint.com">Magnús Þór Torfason</a>
032 * @version $Id: HttpUtils.java 1071052 2011-02-15 20:54:47Z tv $
033 */
034 public class HttpUtils
035 {
036 /**
037 * The date format to use for HTTP Dates.
038 */
039 private static SimpleDateFormat httpDateFormat;
040
041 static
042 {
043 httpDateFormat = new SimpleDateFormat(
044 "EEE, dd MMM yyyy HH:mm:ss z", Locale.US);
045 httpDateFormat.setTimeZone(TimeZone.getTimeZone("GMT"));
046 }
047
048 /**
049 * Formats a java Date according to rfc 1123, the rfc standard for dates in
050 * http.
051 *
052 * @param date The Date to format
053 * @return A String representation of the date
054 */
055 public static String formatHttpDate(Date date)
056 {
057 synchronized (httpDateFormat)
058 {
059 return httpDateFormat.format(date);
060 }
061 }
062
063 /**
064 * This method sets the required expiration headers in the response for a
065 * given RunData object. This method attempts to set all relevant headers,
066 * both for HTTP 1.0 and HTTP 1.1.
067 *
068 * @param data The RunData object we are setting cache information for.
069 * @param expiry The number of milliseconds until the document should expire,
070 * <code>0</code> indicating immediate expiration (i.e. no caching).
071 */
072 public static void setCacheHeaders(RunData data, int expiry)
073 {
074 if (0 == expiry)
075 {
076 data.getResponse().setHeader("Pragma", "no-cache");
077 data.getResponse().setHeader("Cache-Control", "no-cache");
078 data.getResponse().setDateHeader("Expires", System.currentTimeMillis());
079 }
080 else
081 {
082 data.getResponse().setDateHeader("Expires", System.currentTimeMillis() + expiry);
083 }
084 }
085 }