JAva時間処理、Date、Calendar

//  Date
Date date=new Date();
//       
System.out.println(date.getTime());
//            ： 
SimpleDateFormat simpleDateFormat=new SimpleDateFormat("yyyy-MM-dd:ss");
System.out.println(simpleDateFormat.format(date));

//  Calendar，      
Calendar calendar=Calendar.getInstance();
//     
System.out.println(calendar.getTimeInMillis());
//  Date
calendar.setTime(date);
//   
System.out.println(calendar.get(Calendar.YEAR));
//   
System.out.println(calendar.get(Calendar.MARCH));
//   
System.out.println(calendar.get(Calendar.DATE));
//      ，         
calendar.add(Calendar.YEAR,1);
System.out.println(calendar.get(Calendar.YEAR));
//      
calendar.add(Calendar.MARCH,-1);
System.out.println(calendar.get(Calendar.MARCH));
//     
System.out.println(simpleDateFormat.format(calendar.getTime()));


//  System      
System.out.println(System.currentTimeMillis());