1 /*
2 * ====================================================================
3 * Licensed to the Apache Software Foundation (ASF) under one
4 * or more contributor license agreements. See the NOTICE file
5 * distributed with this work for additional information
6 * regarding copyright ownership. The ASF licenses this file
7 * to you under the Apache License, Version 2.0 (the
8 * "License"); you may not use this file except in compliance
9 * with the License. You may obtain a copy of the License at
10 *
11 * http://www.apache.org/licenses/LICENSE-2.0
12 *
13 * Unless required by applicable law or agreed to in writing,
14 * software distributed under the License is distributed on an
15 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
16 * KIND, either express or implied. See the License for the
17 * specific language governing permissions and limitations
18 * under the License.
19 * ====================================================================
20 *
21 * This software consists of voluntary contributions made by many
22 * individuals on behalf of the Apache Software Foundation. For more
23 * information on the Apache Software Foundation, please see
24 * <http://www.apache.org/>.
25 *
26 */
27
28 package org.apache.hc.core5.http.protocol;
29
30 import java.time.Instant;
31 import java.time.ZoneId;
32 import java.time.format.DateTimeFormatter;
33 import java.time.format.DateTimeFormatterBuilder;
34 import java.util.TimeZone;
35
36 import org.apache.hc.core5.annotation.Contract;
37 import org.apache.hc.core5.annotation.ThreadingBehavior;
38
39 /**
40 * Generates a date in the format required by the HTTP protocol.
41 *
42 * @since 4.0
43 */
44 @Contract(threading = ThreadingBehavior.SAFE)
45 public class HttpDateGenerator {
46
47 private static final int GRANULARITY_MILLIS = 1000;
48
49 /** Date format pattern used to generate the header in RFC 1123 format. */
50 public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";
51
52 /**
53 * @deprecated This attribute is no longer supported as a part of the public API.
54 * The time zone to use in the date header.
55 */
56 @Deprecated
57 public static final TimeZone GMT = TimeZone.getTimeZone("GMT");
58
59 public static final ZoneId GMT_ID = ZoneId.of("GMT");
60
61 /** Singleton instance. */
62 public static final HttpDateGenerator INSTANCE = new HttpDateGenerator(PATTERN_RFC1123, GMT_ID);
63
64 private final DateTimeFormatter dateTimeFormatter;
65 private long dateAsMillis;
66 private String dateAsText;
67 private ZoneId zoneId;
68
69 HttpDateGenerator() {
70 dateTimeFormatter =new DateTimeFormatterBuilder()
71 .parseLenient()
72 .parseCaseInsensitive()
73 .appendPattern(PATTERN_RFC1123)
74 .toFormatter();
75 zoneId = GMT_ID;
76
77 }
78
79 private HttpDateGenerator(final String pattern, final ZoneId zoneId) {
80 dateTimeFormatter = new DateTimeFormatterBuilder()
81 .parseLenient()
82 .parseCaseInsensitive()
83 .appendPattern(pattern)
84 .toFormatter();
85 this.zoneId = zoneId;
86 }
87
88 public synchronized String getCurrentDate() {
89 final long now = System.currentTimeMillis();
90 if (now - this.dateAsMillis > GRANULARITY_MILLIS) {
91 // Generate new date string
92 dateAsText = dateTimeFormatter.format(Instant.now().atZone(zoneId));
93 dateAsMillis = now;
94 }
95 return dateAsText;
96 }
97
98 }