-
-
Notifications
You must be signed in to change notification settings - Fork 392
/
CachedDateFormatStrategy.java
80 lines (69 loc) · 3 KB
/
CachedDateFormatStrategy.java
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
/*
* Copyright (c) 2010-2020 Mark Allen, Norbert Bartels.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package com.restfb.util;
import java.lang.ref.SoftReference;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.HashMap;
import java.util.Map;
import java.util.TimeZone;
/**
* a DateFormat strategy that returns a cached SimpleDateFormat instance.
*
* For every format string an instance of the SimpleDateFormat is saved on a per thread base, so the SimpleDateFormat
* instance is reused and you get an major speedup.
*
* Attention: to prevent a possible memory leak while using this strategy you have to clean up the inner ThreadLocal
* with the {@code clearThreadLocal} method.
*
* @since 1.7.0
*/
public class CachedDateFormatStrategy implements DateFormatStrategy {
@Override
public DateFormat formatFor(String format) {
return SimpleDateFormatHolder.formatFor(format);
}
public void clearThreadLocal() {
SimpleDateFormatHolder.clearThreadLocal();
}
private static final class SimpleDateFormatHolder {
private static final ThreadLocal<SoftReference<Map<String, SimpleDateFormat>>> THREADLOCAL_FORMATTER_MAP =
ThreadLocal.withInitial(() -> new SoftReference<>(new HashMap<>()));
private static SimpleDateFormat formatFor(String pattern) {
SoftReference<Map<String, SimpleDateFormat>> ref = THREADLOCAL_FORMATTER_MAP.get();
Map<String, SimpleDateFormat> formatterMap = ref.get();
if (null == formatterMap) {
formatterMap = new HashMap<>();
THREADLOCAL_FORMATTER_MAP.set(new SoftReference<>(formatterMap));
}
return formatterMap.computeIfAbsent(pattern, SimpleDateFormatHolder::createSDF);
}
private static SimpleDateFormat createSDF(String pattern) {
SimpleDateFormat sdf = new SimpleDateFormat(pattern);
sdf.setTimeZone(TimeZone.getTimeZone("UTC"));
return sdf;
}
private static void clearThreadLocal() {
THREADLOCAL_FORMATTER_MAP.remove();
}
}
}