Simple Java function to parse timestamps in many different sources to a valid Java long timestamp in milliseconds.

TimestampUtils

public static long parseTimestamp(String strTimestamp){
    /** Parsing inconsistent timestamps:
     *  1 - Sometime they are longs         e.g. 230923409234       (Timestamp in milliseconds)
     *  2 - Another format is double        e.g. 234234234.234      (Timestamp in milliseconds / 1000)
     *  3 - Even integers on occasion       e.g. 234234234          (Timestamp in seconds)
     *  4 - Also e-notation                 e.g. 1.382298592059E9   (Timestamp in milliseconds / 1000)
     *  5 - And e-notation for doubles      e.g. 1.380604046071e+12 (Timestamp in milliseconds)
     *  
     *  All timestamps in seconds are less than the maximum value of an Integer (2147483647).
     *  All timestamps in milliseconds are greater than the maximum value of an Integer (2147483647).
     *  Thus if it is less than this value multiply by 1000.
     *
     *  Whichever format it is, this code will convert it to a timestamp in milliseconds.
    */
    Long timestamp;
    double dblTimestamp = Double.parseDouble(strTimestamp);
    timestamp = Math.round(dblTimestamp * (dblTimestamp < Integer.MAX_VALUE ? 1000 : 1));
    return timestamp;
}

Note that this will divide second timestamps by 1000 if they are after 2038