Go语言学习之time包(获取当前时间戳等)(the way to go)
生命不止，继续 go go go !!!
每种语言都需要对时间进行处理，golang当然也不例外，go语言为我们提供了time package用于各种时间的转换，处理。
Package time provides functionality for measuring and displaying time.
获取当前时间
func Now
func Now() TimeNow returns the current local time.
func (Time) UTC
func (t Time) UTC() TimeUTC returns t with the location set to UTC.
func (Time) Unix
func (t Time) Unix() int64Unix returns t as a Unix time, the number of seconds elapsed since January 1, 1970 UTC.
func (Time) UnixNano
func (t Time) UnixNano() int64UnixNano returns t as a Unix time, the number of nanoseconds elapsed since January 1, 1970 UTC.
看到Unix和UnixNano的区别了吧，就是精度不同而已：
package main
import (
"fmt"
"strconv"
"time"
)
func main() {
t := time.Now()
fmt.Println(t)
fmt.Println(t.UTC().Format(time.UnixDate))
fmt.Println(t.Unix())
timestamp := strconv.FormatInt(t.UTC().UnixNano(), 10)
fmt.Println(timestamp)
timestamp = timestamp[:10]
fmt.Println(timestamp)
}
输出：
2017-06-21 11:52:29.0826692 +0800 CST
Wed Jun 21 03:52:29 UTC 2017
1498017149
1498017149082669200
1498017149
时间格式化字符串转换
func Parse
package main
import (
"fmt"
"strconv"
"time"
)
func main() {
const longForm = "Jan 2, 2006 at 3:04pm (MST)"
t, _ := time.Parse(longForm, "Jun 21, 2017 at 0:00am (PST)")
fmt.Println(t)
const shortForm = "2006-Jan-02"
t, _ = time.Parse(shortForm, "2017-Jun-21")
fmt.Println(t)
t, _ = time.Parse("01/02/2006", "06/21/2017")
fmt.Println(t)
fmt.Println(t.Unix())
i, err := strconv.ParseInt("1498003200", 10, 64)
if err != nil {
panic(err)
}
tm := time.Unix(i, 0)
fmt.Println(tm)
var timestamp int64 = 1498003200
tm2 := time.Unix(timestamp, 0)
fmt.Println(tm2.Format("2006-01-02 03:04:05 PM"))
fmt.Println(tm2.Format("02/01/2006 15:04:05 PM"))
}
输出：
2017-06-21 00:00:00 +0000 PST
2017-06-21 00:00:00 +0000 UTC
2017-06-21 00:00:00 +0000 UTC
1498003200
2017-06-21 08:00:00 +0800 CST
2017-06-21 08:00:00 AM
21/06/2017 08:00:00 AM
再看一个例子：
package main
import (
"fmt"
"strings"
"time"
)
func main() {
var dates [4]time.Time
dates[0], _ = time.Parse("2006-01-02 15:04:05.000000000 MST -07:00", "1609-09-12 19:02:35.123456789 PDT +03:00")
dates[1], _ = time.Parse("2006-01-02 03:04:05 PM -0700", "1995-11-07 04:29:43 AM -0209")
dates[2], _ = time.Parse("PM -0700 01/02/2006 03:04:05", "AM -0209 11/07/1995 04:29:43")
dates[3], _ = time.Parse("Time:Z07:00T15:04:05 Date:2006-01-02 ", "Time:-03:30T19:18:35 Date:2119-10-29")
defaultFormat := "2006-01-02 15:04:05 PM -07:00 Jan Mon MST"
formats := []map[string]string{
{"format": "2006", "description": "Year"},
{"format": "06", "description": "Year"},
{"format": "01", "description": "Month"},
{"format": "1", "description": "Month"},
{"format": "Jan", "description": "Month"},
{"format": "January", "description": "Month"},
{"format": "02", "description": "Day"},
{"format": "2", "description": "Day"},
{"format": "Mon", "description": "Week day"},
{"format": "Monday", "description": "Week day"},
{"format": "03", "description": "Hours"},
{"format": "3", "description": "Hours"},
{"format": "15", "description": "Hours"},
{"format": "04", "description": "Minutes"},
{"format": "4", "description": "Minutes"},
{"format": "05", "description": "Seconds"},
{"format": "5", "description": "Seconds"},
{"format": "PM", "description": "AM or PM"},
{"format": ".000", "description": "Miliseconds"},
{"format": ".000000", "description": "Microseconds"},
{"format": ".000000000", "description": "Nanoseconds"},
{"format": "-0700", "description": "Timezone offset"},
{"format": "-07:00", "description": "Timezone offset"},
{"format": "Z0700", "description": "Timezone offset"},
{"format": "Z07:00", "description": "Timezone offset"},
{"format": "MST", "description": "Timezone"}}
for _, date := range dates {
fmt.Printf("\n\n %s \n", date.Format(defaultFormat))
fmt.Printf("%-15s + %-12s + %12s \n", strings.Repeat("-", 15), strings.Repeat("-", 12), strings.Repeat("-", 12))
fmt.Printf("%-15s | %-12s | %12s \n", "Type", "Placeholder", "Value")
fmt.Printf("%-15s + %-12s + %12s \n", strings.Repeat("-", 15), strings.Repeat("-", 12), strings.Repeat("-", 12))
for _, f := range formats {
fmt.Printf("%-15s | %-12s | %-12s \n", f["description"], f["format"], date.Format(f["format"]))
}
fmt.Printf("%-15s + %-12s + %12s \n", strings.Repeat("-", 15), strings.Repeat("-", 12), strings.Repeat("-", 12))
}
}
time包的一些其他用法
time包很强大，这里不能整个篇幅的进行介绍，可以自己去看官方的文档。
func Date
func Date(year int, month Month, day, hour, min, sec, nsec int, loc *Location) Timetime常用方法
After(u Time) bool
时间类型比较,是否在Time之后
Before(u Time) bool
时间类型比较,是否在Time之前
Equal(u Time) bool
比较两个时间是否相等
IsZero() bool
判断时间是否为零值,如果sec和nsec两个属性都是0的话,则该时间类型为0
Date() (year int, month Month, day int)
返回年月日,三个参数
Year() int
返回年份
Month() Month
返回月份.是Month类型
Day() int
返回多少号
Weekday() Weekday
返回星期几,是Weekday类型
ISOWeek() (year, week int)
返回年份,和该填是在这年的第几周.
Clock() (hour, min, sec int)
返回小时,分钟,秒
Hour() int
返回小时
Minute() int
返回分钟
Second() int
返回秒数
Nanosecond() int
返回纳秒
应用：
package main
import "fmt"
import "time"
func main() {
p := fmt.Println
now := time.Now()
p(now)
then := time.Date(
2017, 06, 21, 20, 34, 58, 0, time.UTC)
p(then)
p(then.Year())
p(then.Month())
p(then.Day())
p(then.Hour())
p(then.Minute())
p(then.Second())
p(then.Nanosecond())
p(then.Location())
p(then.Weekday())
p(then.Before(now))
p(then.After(now))
p(then.Equal(now))
diff := now.Sub(then)
p(diff)
p(diff.Hours())
p(diff.Minutes())
p(diff.Seconds())
p(diff.Nanoseconds())
p(then.Add(diff))
p(then.Add(-diff))
}
输出：
2017-06-21 13:22:36.5138633 +0800 CST
2017-06-21 20:34:58 +0000 UTC
2017
June
21
20
34
58
0
UTC
Wednesday
false
true
false
-15h12m21.4861367s
-15.205968371305556
-912.3581022783334
-54741.4861367
-54741486136700
2017-06-21 05:22:36.5138633 +0000 UTC
2017-06-22 11:47:19.4861367 +0000 UTC