Question

如何将UTC时间转换为本地时间？

我为当地时间所需的所有国家/地区创建了一张UTC差异地图。然后我将该差异作为持续时间添加到当前时间（UTC）并打印结果，希望这是该特定国家/地区的当地时间。

由于某些原因，结果是错误的。例如，Hungary有一个小时的差异。知道为什么我的结果不正确吗？

package main

import "fmt"
import "time"

func main() {

    m := make(map[string]string)
    m["Hungary"] = "+01.00h"

    offSet, err := time.ParseDuration(m["Hungary"])
    if err != nil {
        panic(err)
    }
    t := time.Now().UTC().Add(offSet)
    nice := t.Format("15:04")

    fmt.Println(nice)
}

Answer 1

请注意，游乐场的时间设置为2009-11-10 23:00:00 +0000 UTC，因此它正常运行。

正确的方法是使用time.LoadLocation，这是一个例子：

var countryTz = map[string]string{
    "Hungary": "Europe/Budapest",
    "Egypt":   "Africa/Cairo",
}

func timeIn(name string) time.Time {
    loc, err := time.LoadLocation(countryTz[name])
    if err != nil {
        panic(err)
    }
    return time.Now().In(loc)
}

func main() {
    utc := time.Now().UTC().Format("15:04")
    hun := timeIn("Hungary").Format("15:04")
    eg := timeIn("Egypt").Format("15:04")
    fmt.Println(utc, hun, eg)
}

Answer 2

你的方法存在缺陷。一个国家可以有几个时区，例如美国和俄罗斯。由于夏令时（DST），时区可以有多次，例如匈牙利。匈牙利的UTC为+1：00，DST也是UTC + 2:00。

对于您希望获得给定UTC时间的本地时间的每个位置，请使用IANA（tzdata）时区位置。例如，

package main

import (
    "fmt"
    "time"
)

func main() {
    utc := time.Now().UTC()
    fmt.Println(utc)
    local := utc
    location, err := time.LoadLocation("Europe/Budapest")
    if err == nil {
        local = local.In(location)
    }
    fmt.Println("UTC", utc.Format("15:04"), local.Location(), local.Format("15:04"))
    local = utc
    location, err = time.LoadLocation("America/Los_Angeles")
    if err == nil {
        local = local.In(location)
    }
    fmt.Println("UTC", utc.Format("15:04"), local.Location(), local.Format("15:04"))
}

输出：

2014-08-14 23:57:09.151377514 +0000 UTC
UTC 23:57 Europe/Budapest 01:57
UTC 23:57 America/Los_Angeles 16:57

参考文献：

IANA Time Zone Database

tz database

tz database time zones

Time zone

Time in Hungary

Answer 3

避免弄乱特定区域的麻烦，使用位置＆＃34; Local＆＃34;。这是本地和UTC转换的完整实用示例：

package main

import (
    "fmt"
    "log"
    "time"
)

const (
    dateTimeFormat = "2006-01-02 15:04 MST"
    dateFormat    = "2006-01-02"
    timeFormat    = "15:04"
)

// A full cycle example of receiving local date and time,
// handing off to a database, retrieving as UTC, and formatting as local datetime
// This should be good in *any* timezone
func main() {
    // If using a form for entry, I strongly suggest a controlled format input like
    // <input type="date" ... > and <input type="time" ... >
    locallyEnteredDate := "2017-07-16"
    locallyEnteredTime := "14:00"

    // Build a time object from received fields (time objects include zone info)
    // We are assuming the code is running on a server that is in the same zone as the current user
    zone, _ := time.Now().Zone() // get the local zone
    dateTimeZ := locallyEnteredDate + " " + locallyEnteredTime + " " + zone
    dte, err := time.Parse(dateTimeFormat, dateTimeZ)
    if err != nil {
        log.Fatal("Error parsing entered datetime", err)
    }
    fmt.Println("dte:", dte) // dte is a legit time object
    // Perhaps we are saving this in a database.
    // A good database driver should save the time object as UTC in a time with zone field,
    // and return a time object with UTC as zone.

    // For the sake of this example, let's assume an object identical to `dte` is returned
    // dte := ReceiveFromDatabase()

    // Convert received date to local.
    // Note the use of the convenient "Local" location https://golang.org/pkg/time/#LoadLocation.
    localLoc, err := time.LoadLocation("Local")
    if err != nil {
        log.Fatal(`Failed to load location "Local"`)
    }
    localDateTime := dte.In(localLoc)

    fmt.Println("Date:", localDateTime.Format(dateFormat))
    fmt.Println("Time:", localDateTime.Format(timeFormat))
}

将UTC转换为＆＃34; local＆＃34; Go的时间

3 个答案: