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 }