1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * http://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17 package org.apache.commons.lang3.time;
18
19 import java.util.TimeZone;
20 import java.util.regex.Matcher;
21 import java.util.regex.Pattern;
22
23 /**
24 * Faster methods to produce custom time zones.
25 *
26 * @since 3.7
27 */
28 public class FastTimeZone {
29
30 private static final Pattern GMT_PATTERN = Pattern.compile("^(?:(?i)GMT)?([+-])?(\\d\\d?)?(:?(\\d\\d?))?$");
31
32 private static final TimeZone GREENWICH = new GmtTimeZone(false, 0, 0);
33
34 /**
35 * Gets the GMT TimeZone.
36 * @return A TimeZone with a raw offset of zero.
37 */
38 public static TimeZone getGmtTimeZone() {
39 return GREENWICH;
40 }
41
42 /**
43 * Gets a TimeZone with GMT offsets. A GMT offset must be either 'Z', or 'UTC', or match
44 * <em>(GMT)? hh?(:?mm?)?</em>, where h and m are digits representing hours and minutes.
45 *
46 * @param pattern The GMT offset
47 * @return A TimeZone with offset from GMT or null, if pattern does not match.
48 */
49 public static TimeZone getGmtTimeZone(final String pattern) {
50 if ("Z".equals(pattern) || "UTC".equals(pattern)) {
51 return GREENWICH;
52 }
53
54 final Matcher m = GMT_PATTERN.matcher(pattern);
55 if (m.matches()) {
56 final int hours = parseInt(m.group(2));
57 final int minutes = parseInt(m.group(4));
58 if (hours == 0 && minutes == 0) {
59 return GREENWICH;
60 }
61 return new GmtTimeZone(parseSign(m.group(1)), hours, minutes);
62 }
63 return null;
64 }
65
66 /**
67 * Gets a TimeZone, looking first for GMT custom ids, then falling back to Olson ids.
68 * A GMT custom id can be 'Z', or 'UTC', or has an optional prefix of GMT,
69 * followed by sign, hours digit(s), optional colon(':'), and optional minutes digits.
70 * i.e. <em>[GMT] (+|-) Hours [[:] Minutes]</em>
71 *
72 * @param id A GMT custom id (or Olson id
73 * @return A time zone
74 */
75 public static TimeZone getTimeZone(final String id) {
76 final TimeZone tz = getGmtTimeZone(id);
77 if (tz != null) {
78 return tz;
79 }
80 return TimeZone.getTimeZone(id);
81 }
82
83 private static int parseInt(final String group) {
84 return group != null ? Integer.parseInt(group) : 0;
85 }
86
87 private static boolean parseSign(final String group) {
88 return group != null && group.charAt(0) == '-';
89 }
90
91 // do not instantiate
92 private FastTimeZone() {
93 }
94
95 }