How to parse a milliseconds-since-epoch timestamp string in Go?

I've got a string with milliseconds since the epoch (it came originally from a java.lang.System.currentTimeMillis() call). What's the right way to convert this string into a human readable timestamp string in Go?

Looking at the time package I see the Parse function, but the layouts all seem to be normal timezone-based times. Once into a Time object, I can use Format(Time.Stamp) to get the output I want, but I'm not clear on how to get the string into a Time object.

The format string does not support milliseconds since the epoch, so you need to parse manually. For example:

func msToTime(ms string) (time.Time, error) {
    msInt, err := strconv.ParseInt(ms, 10, 64)
    if err != nil {
        return time.Time{}, err
    }

    return time.Unix(0, msInt*int64(time.Millisecond)), nil
}

Check out http://play.golang.org/p/M1dWGLT8XE to play with the example live.

2021 update: you can use UnixMilli to parse from the integer. This would improve the accepted answer to:

 func msToTime(ms string) (time.Time, error) {
    msInt, err := strconv.ParseInt(ms, 10, 64)
    if err != nil {
        return time.Time{}, err
    }

    return time.UnixMilli(msInt), nil
}

The accepted answer will not work for some date ranges either too far in the future or too far in the past because only a limited date range can be described using 64 bits (plus or minus 300 years from Epoch).

This will work for the entire range describable by milliseconds:

var Epoch = time.Unix(0, 0)

func ParseMillisecondUnixTimestamp(s string) (time.Time, error) {
	ts, err := strconv.Atoi(s)
	if err != nil {
		return time.Time{}, err
	}

	return Epoch.Add(time.Duration(ts) * time.Millisecond), nil
}

Using time.Unix(ms/1000, 0) would do the trick.

First convert the ms-timestamp to unix-timestamp using the well known relation 1 s = 1000 ms and then use the result as first argument to the time.Unix function