English | 中文
为 Golang 设计的性能超棒的 yyyyMMdd 日期格式化工具。
它是为了解决这个问题而创建的： Golang/go issue: magic number datetime formatting。
// 用常见语法格式化日期和时间
s := datefmt.Format(time.Now(), "yyyy-MM-dd HH:mm:ss")
// 用常见语法解析时间字符串
t, err := datefmt.Parse("yyyy-MM-dd HH:mm:ss", "2022-06-20 09:49:10")
// 用常见语法解析时间字符串，并指定时区
t, err := datefmt.ParseInLocation("yyyy-MM-dd HH:mm:ss", "2022-06-20 09:49:10", time.UTC)可以预先创建格式化布局，以提升性能：
var CommonTimeFormat = datefmt.NewLayout("yyyy-MM-dd HH:mm:ss")
CommonTimeFormat.Format(time.Now())将常见格式化语法转换为 Go 风格的语法：
l := datefmt.GoLayout("yyyy-MM-dd HH:mm:ss") // l = '2006-01-02 15:04:05'datefmt 的格式化语法和 Java 中的定义 一致。
对标准的支持情况如下：
| 字母 | 说明 | 示例 | datefmt | std format | std parse |
|---|---|---|---|---|---|
| G | Era designator | AD | ✓ | ||
| y | Year | 1996; 96 | ✓ | ✓1 | ✓1 |
| Y | Week year | 2009; 09 | ✓ | ✓2 | ✓2 |
| M | Month in year | July; Jul; 07 | ✓ | ✓ | ✓ |
| w | Week in year | 27 | ✓ | ||
| W | Week in month | 2 | ✓ | ||
| D | Day in year | 189 | ✓ | ✓ | ✓ |
| d | Day in month | 10 | ✓ | ✓ | ✓ |
| F | Day of week in month | 2 | ✓ | ||
| E | Day name in week | Tuesday; Tue | ✓ | ✓ | ✓ |
| u | Day number of week (1-7) | 1 | ✓ | ||
| a | Am/pm marker | PM | ✓ | ✓ | ✓ |
| H | Hour in day (0-23) | 0 | ✓ | ✓ | ✓ |
| k | Hour in day (1-24) | 24 | ✓ | ||
| K | Hour in am/pm (0-11) | 0 | ✓ | ||
| h | Hour in am/pm (1-12) | 12 | ✓ | ✓ | ✓ |
| m | Minute in hour | 30 | ✓ | ✓ | ✓ |
| s | Second in minute | 55 | ✓ | ✓ | ✓ |
| S | Millisecond | 978 | ✓ | ✓ | ✓ |
| z | Time zone | PST; GMT-08:00 | ✓ | ✓ | ✓ |
| Z | Time zone | -800 | ✓ | ✓ | ✓ |
| X | Time zone | -08; -0800; -08:00 | ✓ | ✓ | ✓ |
| ' | Text delimiter | 'o''clock' | ✓ | ✓3 | ✓3 |
datefmt 的性能表现很不错，甚至在大多数情况下比标准库的速度还要快。
下面是 datefmt 和标准库、jodaTime、GoDateFormat 对比下的基准测试结果：
BenchmarkFormat/datefmt______yyyy-MM-dd_HH:mm:ss-8 7447152 161.7 ns/op 24 B/op 1 allocs/op
BenchmarkFormat/std.Format___yyyy-MM-dd_HH:mm:ss-8 6057490 214.9 ns/op 24 B/op 1 allocs/op
BenchmarkFormat/jodaTime_____yyyy-MM-dd_HH:mm:ss-8 1455223 817.3 ns/op 208 B/op 18 allocs/op
BenchmarkFormat/GoDateFormat_yyyy-MM-dd_HH:mm:ss-8 1495375 810.4 ns/op 168 B/op 7 allocs/op
BenchmarkFormat/datefmt______yyyy-MM-dd'T'HH:mm:ss_z-8 5913645 203.9 ns/op 32 B/op 1 allocs/op
BenchmarkFormat/std.Format___yyyy-MM-dd'T'HH:mm:ss_z-8 5850758 217.3 ns/op 24 B/op 1 allocs/op
BenchmarkFormat/jodaTime_____yyyy-MM-dd'T'HH:mm:ss_z-8 1214950 999.5 ns/op 256 B/op 22 allocs/op
BenchmarkFormat/GoDateFormat_yyyy-MM-dd'T'HH:mm:ss_z-8 1296421 903.4 ns/op 208 B/op 8 allocs/op
BenchmarkFormat/datefmt______yyMMddHHmmssZ-8 6011174 179.6 ns/op 24 B/op 1 allocs/op
BenchmarkFormat/std.Format___yyMMddHHmmssZ-8 6345073 192.5 ns/op 24 B/op 1 allocs/op
BenchmarkFormat/jodaTime_____yyMMddHHmmssZ-8 1683231 710.1 ns/op 136 B/op 12 allocs/op
BenchmarkFormat/GoDateFormat_yyMMddHHmmssZ-8 1394109 869.9 ns/op 128 B/op 8 allocs/op
BenchmarkFormat/datefmt______EEE,_MMM_DDD,_''yy-8 6854894 174.7 ns/op 24 B/op 1 allocs/op
BenchmarkFormat/std.Format___EEE,_MMM_DDD,_''yy-8 8224816 160.3 ns/op 24 B/op 1 allocs/op
BenchmarkFormat/jodaTime_____EEE,_MMM_DDD,_''yy-8 2169121 545.2 ns/op 112 B/op 14 allocs/op
BenchmarkFormat/GoDateFormat_EEE,_MMM_DDD,_''yy-8 2567779 468.8 ns/op 72 B/op 3 allocs/op
BenchmarkFormat/datefmt______h:mm_a-8 13415570 86.86 ns/op 8 B/op 1 allocs/op
BenchmarkFormat/std.Format___h:mm_a-8 10746708 112.0 ns/op 8 B/op 1 allocs/op
BenchmarkFormat/jodaTime_____h:mm_a-8 4197170 289.3 ns/op 32 B/op 6 allocs/op
BenchmarkFormat/GoDateFormat_h:mm_a-8 3587061 340.9 ns/op 16 B/op 2 allocs/op
PASS
ok bench 34.733s