1 /* 2 * $HeadURL: http://svn.apache.org/repos/asf/httpcomponents/httpcore/trunk/module-main/src/main/java/org/apache/http/protocol/HttpDateGenerator.java $ 3 * $Revision: 548066 $ 4 * $Date: 2007-06-17 09:51:55 -0700 (Sun, 17 Jun 2007) $ 5 * 6 * ==================================================================== 7 * Licensed to the Apache Software Foundation (ASF) under one 8 * or more contributor license agreements. See the NOTICE file 9 * distributed with this work for additional information 10 * regarding copyright ownership. The ASF licenses this file 11 * to you under the Apache License, Version 2.0 (the 12 * "License"); you may not use this file except in compliance 13 * with the License. You may obtain a copy of the License at 14 * 15 * http://www.apache.org/licenses/LICENSE-2.0 16 * 17 * Unless required by applicable law or agreed to in writing, 18 * software distributed under the License is distributed on an 19 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 20 * KIND, either express or implied. See the License for the 21 * specific language governing permissions and limitations 22 * under the License. 23 * ==================================================================== 24 * 25 * This software consists of voluntary contributions made by many 26 * individuals on behalf of the Apache Software Foundation. For more 27 * information on the Apache Software Foundation, please see 28 * <http://www.apache.org/>. 29 * 30 */ 31 32 package org.apache.http.protocol; 33 34 import java.text.DateFormat; 35 import java.text.SimpleDateFormat; 36 import java.util.Date; 37 import java.util.Locale; 38 import java.util.TimeZone; 39 40 41 /** 42 * Generates a date in the format required by the HTTP protocol. 43 * 44 * @author <a href="mailto:oleg at ural.ru">Oleg Kalnichevski</a> 45 * 46 * @version $Revision: 548066 $ 47 * 48 * @since 4.0 49 */ 50 public class HttpDateGenerator { 51 52 /** Date format pattern used to generate the header in RFC 1123 format. */ 53 public static final 54 String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz"; 55 56 /** The time zone to use in the date header. */ 57 public static final TimeZone GMT = TimeZone.getTimeZone("GMT"); 58 59 60 private final DateFormat dateformat; 61 62 private long dateAsLong = 0L; 63 private String dateAsText = null; 64 HttpDateGenerator()65 public HttpDateGenerator() { 66 super(); 67 this.dateformat = new SimpleDateFormat(PATTERN_RFC1123, Locale.US); 68 this.dateformat.setTimeZone(GMT); 69 } 70 getCurrentDate()71 public synchronized String getCurrentDate() { 72 long now = System.currentTimeMillis(); 73 if (now - this.dateAsLong > 1000) { 74 // Generate new date string 75 this.dateAsText = this.dateformat.format(new Date(now)); 76 this.dateAsLong = now; 77 } 78 return this.dateAsText; 79 } 80 81 } 82