Go语言学习之time包(获取当前时间戳等)(the way to 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() Time
1
Now returns the current local time.

func (Time) UTC

func (t Time) UTC() Time
1
UTC returns t with the location set to UTC.

func (Time) Unix

func (t Time) Unix() int64
1
Unix returns t as a Unix time, the number of seconds elapsed since January 1, 1970 UTC.

func (Time) UnixNano

func (t Time) UnixNano() int64
1
UnixNano 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)
}
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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"))
}

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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))
    }
}
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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) Time
1
time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))
}
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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
--------------------- 
原文：https://blog.csdn.net/wangshubo1989/article/details/73543377