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 import java.util.concurrent.locks.ReentrantLock;
36
37 import org.apache.hc.core5.annotation.Contract;
38 import org.apache.hc.core5.annotation.ThreadingBehavior;
39
40 /**
41 * Generates a date in the format required by the HTTP protocol.
42 *
43 * @since 4.0
44 */
45 @Contract(threading = ThreadingBehavior.SAFE)
46 public class HttpDateGenerator {
47
48 private static final int GRANULARITY_MILLIS = 1000;
49
50 /**
51 * @deprecated Use {@link #INTERNET_MESSAGE_FORMAT}
52 */
53 @Deprecated
54 public static final String PATTERN_RFC1123 = "EEE, dd MMM yyyy HH:mm:ss zzz";
55 public static final String INTERNET_MESSAGE_FORMAT = "EEE, dd MMM yyyy HH:mm:ss zzz";
56
57 /**
58 * @deprecated This attribute is no longer supported as a part of the public API.
59 * The time zone to use in the date header.
60 */
61 @Deprecated
62 public static final TimeZone GMT = TimeZone.getTimeZone("GMT");
63
64 public static final ZoneId GMT_ID = ZoneId.of("GMT");
65
66 /** Singleton instance. */
67 public static final HttpDateGenerator INSTANCE = new HttpDateGenerator(INTERNET_MESSAGE_FORMAT, GMT_ID);
68
69 private final DateTimeFormatter dateTimeFormatter;
70 private long dateAsMillis;
71 private String dateAsText;
72 private ZoneId zoneId;
73
74 private final ReentrantLock lock;
75
76 private HttpDateGenerator(final String pattern, final ZoneId zoneId) {
77 dateTimeFormatter = new DateTimeFormatterBuilder()
78 .parseLenient()
79 .parseCaseInsensitive()
80 .appendPattern(pattern)
81 .toFormatter();
82 this.zoneId = zoneId;
83 this.lock = new ReentrantLock();
84 }
85
86 public String getCurrentDate() {
87 lock.lock();
88 try {
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 } finally {
97 lock.unlock();
98 }
99 }
100
101 }