使用java代码将时间戳和时间互相转换

SimpleDateFormat simpleDateFormat = null;

simpleDateFormat = new SimpleDateFormat("yyyyMMdd");

Date date = new Date(System.currentTimeMillis());
String day = simpleDateFormat.format(date);

simpleDateFormat = new SimpleDateFormat("HHmmss");  
String time = simpleDateFormat1.format(date);

SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = simpleDateFormat.parse(s);
long ts = date.getTime();