Calendar,Date,long(Millis)转换

Calendar,Date,long(Millis)转换
Calendar与Date、long的转换：
  Calendar ca = Calendar.getInstance();
  Date d = ca.getTime();
  long l = ca.getTimeInMillis();
  ca.setTime(d);
  ca.setTimeInMillis(l);

Date和long间的转换：
  Date d = new Date();
  long l = d.getTime();
  d.setTime(l);
  d = new Date(l);