golang 时间格式化要指定默认的格式，如果不指定默认的格式就会出现错误，如果一个未知的时间格式需要做格式化，是比较棘手的。
下面是我在项目写的一个时间格式化函数，简单的支持几种格式

package util

import (
    "strings"
    "time"
)

func TimeParseLocal(in string) (out time.Time, err error) {
    birStrLen := strings.Count(in, "") - 1
    switch birStrLen {
    case 10:
        //2006-01-02
        return TimeParse10(in)
    case 19:
        //2006-01-02 15:04:05
        return TimeParse19(in)
    default:
    }
    return
}

// yyyy-mm-dd | mm-dd-yyyy 格式
func TimeParse10(in string) (out time.Time, err error) {
    chars := []rune(in)
    fc := ""
    for k, char := range chars {
        if char == '-' || char == '/' || char == ':' || char == '.' {
            fc = string(char)
        }
        switch {
        case (k == 0) && ((char <= ('Z') && char >= ('A')) || (char <= ('z') && char >= ('a'))):
            // 这个是  Jun-MM-YYYY 格式
        case (k == 2) && (char == '-' || char == '/' || char == ':' || char == '.'):
            return TimeParseMMDDYYYY(in, string(char))
        case (k == 4) && (char == '-' || char == '/' || char == ':' || char == '.'):
            return TimeParseYYYYMMDD(in, string(char))
        }
    }
    return TimeParseYYYYMMDD(in, fc)
}

// yyyy-mm-dd hh:mm:ss | mm-dd-yyyy hh:mm:ss 格式
func TimeParse19(in string) (out time.Time, err error) {
    chars := []rune(in)
    fc := ""
    for k, char := range chars {
        if char == '-' || char == '/' || char == ':' || char == '.' {
            fc = string(char)
        }
        switch {
        case (k == 0) && ((char <= ('Z') && char >= ('A')) || (char <= ('z') && char >= ('a'))):
            // 这个是  Jun-MM-YYYY 格式
        case (k == 2) && (char == '-' || char == '/' || char == ':' || char == '.'):
            return TimeParseMMDDYYYYHHMMSS(in, string(char))
        case (k == 4) && (char == '-' || char == '/' || char == ':' || char == '.'):
            return TimeParseYYYYMMDDHHMMSS(in, string(char))
        }
    }
    return TimeParseYYYYMMDDHHMMSS(in, fc)
}

func TimeParseYYYYMMDD(in string, sub string) (out time.Time, err error) {
    layout := "2006" + sub + "01" + sub + "02"
    out, err = time.ParseInLocation(layout, in, time.Local)
    if err != nil {
        return
    }
    return
}

func TimeParseMMDDYYYY(in string, sub string) (out time.Time, err error) {
    layout := "01" + sub + "02" + sub + "2006"
    out, err = time.ParseInLocation(layout, in, time.Local)
    if err != nil {
        return
    }
    return
}

func TimeParseYYYYMMDDHHMMSS(in string, sub string) (out time.Time, err error) {
    layout := "2006" + sub + "01" + sub + "02 15:04:05"
    out, err = time.ParseInLocation(layout, in, time.Local)
    if err != nil {
        return
    }
    return
}

func TimeParseMMDDYYYYHHMMSS(in string, sub string) (out time.Time, err error) {
    layout := "01" + sub + "02" + sub + "2006 15:04:05"
    out, err = time.ParseInLocation(layout, in, time.Local)
    if err != nil {
        return
    }
    return
}

测试

package util

import (
    "testing"
)

func TestTimeParseLocal(t *testing.T) {
    t.Log(TimeParseLocal("2019/03/26"))
    t.Log(TimeParseLocal("03/26/2019"))
    t.Log(TimeParseLocal("2019/03/26 17:30:03"))
    t.Log(TimeParseLocal("03/26/2019 17:30:03"))
}