时间转换成毫秒值

private SimpleDateFormat dateformat;
private long time;
private long getMills(){
    dateformat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); //时间格式
    try {
        time = dateformat.parse("1971-01-01 00:00:00").getTime();//格式转换
        System.out.println(time);
    } catch (java.text.ParseException e) {
        e.printStackTrace();
    }
    return time;
}