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 * https://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
18 package org.apache.commons.lang3.time;
19
20 import java.util.TimeZone;
21 import java.util.regex.Matcher;
22 import java.util.regex.Pattern;
23
24 /**
25 * Faster methods to produce custom time zones.
26 *
27 * @since 3.7
28 */
29 public class FastTimeZone {
30
31 private static final Pattern GMT_PATTERN = Pattern.compile("^(?:(?i)GMT)?([+-])?(\\d\\d?)?(:?(\\d\\d?))?$");
32
33 private static final TimeZone GREENWICH = new GmtTimeZone(false, 0, 0);
34
35 /**
36 * Gets the GMT TimeZone.
37 *
38 * @return A TimeZone with a raw offset of zero.
39 */
40 public static TimeZone getGmtTimeZone() {
41 return GREENWICH;
42 }
43
44 /**
45 * Gets a TimeZone with GMT offsets. A GMT offset must be either 'Z', or 'UTC', or match <em>(GMT)? hh?(:?mm?)?</em>, where h and m are digits representing
46 * hours and minutes.
47 *
48 * <p>
49 * Note: the underlying regex is lenient â every capture group (sign, hours, minutes, and the {@code GMT} prefix) is optional. Inputs that lack any digit
50 * group, such as the empty string, {@code "+"}, {@code "-"}, or {@code "GMT"} alone, still match and the method returns the GMT TimeZone with a raw offset
51 * of zero (mirroring {@link TimeZone#getTimeZone(String)} JDK-parity for unrecognized ids). Inputs that fail the regex outright, or that match but specify
52 * an out-of-range offset (24 hours or 60 minutes and above), return {@code null}.
53 * </p>
54 *
55 * @param pattern The GMT offset.
56 * @return A TimeZone matching the (possibly partial or empty) GMT offset pattern, defaulting to GMT for an unrecognized but parseable input, or
57 * {@code null} if the pattern fails the regex or specifies an out-of-range offset.
58 */
59 public static TimeZone getGmtTimeZone(final String pattern) {
60 if ("Z".equals(pattern) || "UTC".equals(pattern)) {
61 return GREENWICH;
62 }
63 final Matcher m = GMT_PATTERN.matcher(pattern);
64 if (m.matches()) {
65 final int hours = parseInt(m.group(2));
66 final int minutes = parseInt(m.group(4));
67 if (hours == 0 && minutes == 0) {
68 return GREENWICH;
69 }
70 if (hours >= 24 || minutes >= 60) {
71 // A matching but out-of-range offset is not a valid GMT id; report it the documented
72 // way instead of letting the GmtTimeZone constructor throw IllegalArgumentException.
73 return null;
74 }
75 return new GmtTimeZone(parseSign(m.group(1)), hours, minutes);
76 }
77 return null;
78 }
79
80 /**
81 * Gets a TimeZone, looking first for GMT custom ids, then falling back to Olson ids. A GMT custom id can be 'Z', or 'UTC', or has an optional prefix of
82 * GMT, followed by sign, hours digit(s), optional colon(':'), and optional minutes digits. i.e. <em>[GMT] (+|-) Hours [[:] Minutes]</em>
83 *
84 * @param id A GMT custom id or Olson id.
85 * @return A time zone.
86 */
87 public static TimeZone getTimeZone(final String id) {
88 final TimeZone tz = getGmtTimeZone(id);
89 return tz != null ? tz : TimeZones.getTimeZone(id);
90 }
91
92 private static int parseInt(final String s) {
93 return s != null ? Integer.parseInt(s) : 0;
94 }
95
96 private static boolean parseSign(final String group) {
97 return group != null && group.charAt(0) == '-';
98 }
99
100 // do not instantiate
101 private FastTimeZone() {
102 }
103
104 }