问题
I am converting a function from PHP to Go.
I want to get timezone from country code in Go. It is similar this function in PHP
public static array DateTimeZone::listIdentifiers ([ int $what = DateTimeZone::ALL [, string $country = NULL ]] )
Which function have similar feature in Go?
回答1:
The Go standard library does not have a function for this. Look for an open-source Go package that does this for you. Or, since this is Go, write a simple Go function yourself. You will have to download the IANA tzdata zone cross-reference file.
For example,
package main
import (
"bufio"
"fmt"
"os"
"path/filepath"
"strings"
"time"
)
// Download IANA tzdata zone file:
// $ wget https://raw.githubusercontent.com/eggert/tz/master/zone1970.tab -O zone1970.tab
// countryZones returns a map of IANA Time Zone Database (tzdata) zone names
// by ISO 3166 2-character country code: map[country][]zone.
func countryZones(dir string) (map[string][]string, error) {
fname := filepath.Join(dir, `zone1970.tab`)
f, err := os.Open(fname)
if err != nil {
return nil, err
}
defer f.Close()
countries := make(map[string][]string)
s := bufio.NewScanner(f)
for s.Scan() {
line := s.Text()
if strings.HasPrefix(line, "#") {
continue
}
n := 3
fields := strings.SplitN(line, "\t", n+1)
if len(fields) < n {
continue
}
zone := fields[2]
for _, country := range strings.Split(fields[0], ",") {
country = strings.ToUpper(country)
zones := countries[country]
zones = append(zones, zone)
countries[country] = zones
}
}
if err = s.Err(); err != nil {
return nil, err
}
return countries, nil
}
func main() {
zones, err := countryZones("")
if err != nil {
fmt.Fprintln(os.Stderr, err)
return
}
utc := time.Now().UTC()
for _, country := range []string{"RU", "CA"} {
fmt.Println("Country:", country)
zones := zones[country]
fmt.Println(utc, "UTC")
for _, zone := range zones {
loc, err := time.LoadLocation(zone)
if err != nil {
fmt.Fprintln(os.Stderr, err)
continue
}
fmt.Println(utc.In(loc), zone)
}
}
}
Output:
$ wget https://raw.githubusercontent.com/eggert/tz/master/zone1970.tab -O zone1970.tab
--2018-07-15 09:44:02-- https://raw.githubusercontent.com/eggert/tz/master/zone1970.tab
Resolving raw.githubusercontent.com (raw.githubusercontent.com)... 151.101.184.133
Connecting to raw.githubusercontent.com (raw.githubusercontent.com)|151.101.184.133|:443... connected.
HTTP request sent, awaiting response... 200 OK
Length: 17810 (17K) [text/plain]
Saving to: ‘zone1970.tab’
zone1970.tab 100%[==================================>] 17.39K --.-KB/s in 0.03s
2018-07-15 09:44:02 (582 KB/s) - ‘zone1970.tab’ saved [17810/17810]
$ go run zones.go
Country: RU
2018-07-15 17:40:03.09524872 +0000 UTC UTC
2018-07-15 19:40:03.09524872 +0200 EET Europe/Kaliningrad
2018-07-15 20:40:03.09524872 +0300 MSK Europe/Moscow
2018-07-15 20:40:03.09524872 +0300 MSK Europe/Simferopol
2018-07-15 20:40:03.09524872 +0300 +03 Europe/Volgograd
2018-07-15 20:40:03.09524872 +0300 +03 Europe/Kirov
2018-07-15 21:40:03.09524872 +0400 +04 Europe/Astrakhan
2018-07-15 21:40:03.09524872 +0400 +04 Europe/Saratov
2018-07-15 21:40:03.09524872 +0400 +04 Europe/Ulyanovsk
2018-07-15 21:40:03.09524872 +0400 +04 Europe/Samara
2018-07-15 22:40:03.09524872 +0500 +05 Asia/Yekaterinburg
2018-07-15 23:40:03.09524872 +0600 +06 Asia/Omsk
2018-07-16 00:40:03.09524872 +0700 +07 Asia/Novosibirsk
2018-07-16 00:40:03.09524872 +0700 +07 Asia/Barnaul
2018-07-16 00:40:03.09524872 +0700 +07 Asia/Tomsk
2018-07-16 00:40:03.09524872 +0700 +07 Asia/Novokuznetsk
2018-07-16 00:40:03.09524872 +0700 +07 Asia/Krasnoyarsk
2018-07-16 01:40:03.09524872 +0800 +08 Asia/Irkutsk
2018-07-16 02:40:03.09524872 +0900 +09 Asia/Chita
2018-07-16 02:40:03.09524872 +0900 +09 Asia/Yakutsk
2018-07-16 02:40:03.09524872 +0900 +09 Asia/Khandyga
2018-07-16 03:40:03.09524872 +1000 +10 Asia/Vladivostok
2018-07-16 03:40:03.09524872 +1000 +10 Asia/Ust-Nera
2018-07-16 04:40:03.09524872 +1100 +11 Asia/Magadan
2018-07-16 04:40:03.09524872 +1100 +11 Asia/Sakhalin
2018-07-16 04:40:03.09524872 +1100 +11 Asia/Srednekolymsk
2018-07-16 05:40:03.09524872 +1200 +12 Asia/Kamchatka
2018-07-16 05:40:03.09524872 +1200 +12 Asia/Anadyr
Country: CA
2018-07-15 17:40:03.09524872 +0000 UTC UTC
2018-07-15 15:10:03.09524872 -0230 NDT America/St_Johns
2018-07-15 14:40:03.09524872 -0300 ADT America/Halifax
2018-07-15 14:40:03.09524872 -0300 ADT America/Glace_Bay
2018-07-15 14:40:03.09524872 -0300 ADT America/Moncton
2018-07-15 14:40:03.09524872 -0300 ADT America/Goose_Bay
2018-07-15 13:40:03.09524872 -0400 AST America/Blanc-Sablon
2018-07-15 13:40:03.09524872 -0400 EDT America/Toronto
2018-07-15 13:40:03.09524872 -0400 EDT America/Nipigon
2018-07-15 13:40:03.09524872 -0400 EDT America/Thunder_Bay
2018-07-15 13:40:03.09524872 -0400 EDT America/Iqaluit
2018-07-15 13:40:03.09524872 -0400 EDT America/Pangnirtung
2018-07-15 12:40:03.09524872 -0500 EST America/Atikokan
2018-07-15 12:40:03.09524872 -0500 CDT America/Winnipeg
2018-07-15 12:40:03.09524872 -0500 CDT America/Rainy_River
2018-07-15 12:40:03.09524872 -0500 CDT America/Resolute
2018-07-15 12:40:03.09524872 -0500 CDT America/Rankin_Inlet
2018-07-15 11:40:03.09524872 -0600 CST America/Regina
2018-07-15 11:40:03.09524872 -0600 CST America/Swift_Current
2018-07-15 11:40:03.09524872 -0600 MDT America/Edmonton
2018-07-15 11:40:03.09524872 -0600 MDT America/Cambridge_Bay
2018-07-15 11:40:03.09524872 -0600 MDT America/Yellowknife
2018-07-15 11:40:03.09524872 -0600 MDT America/Inuvik
2018-07-15 10:40:03.09524872 -0700 MST America/Creston
2018-07-15 10:40:03.09524872 -0700 MST America/Dawson_Creek
2018-07-15 10:40:03.09524872 -0700 MST America/Fort_Nelson
2018-07-15 10:40:03.09524872 -0700 PDT America/Vancouver
2018-07-15 10:40:03.09524872 -0700 PDT America/Whitehorse
2018-07-15 10:40:03.09524872 -0700 PDT America/Dawson
$
回答2:
The timezone is accessible from time.LoadLocation(): example
package main
import (
"fmt"
"time"
"log"
)
func main() {
var ParisLocation, err = time.LoadLocation("Europe/Paris")
if(err != nil) {
log.Fatal(err)
}
fmt.Println(ParisLocation)
}
As seen in golang/go issue 21881, it won't work on Windows because $GOROOT/lib/time/zoneinfo.zip is not included by default, hence the need for projects like 4d63.com/tz.
来源：https://stackoverflow.com/questions/51346476/how-to-get-timezone-from-country