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);    
  
long d2;   
System.out.println(d2=new Date().getTime());   
new Date(d2);   
new Date(1257304282376L);//要带l/L,否则会认为是int 越界