如何利用java得到當前的時間和前一天的時間

1.得到當前的時間 

Calendar   cal   =   Calendar.getInstance();
String time=formatter.format(cal.getTime());
String strEnd=time.substring(0, 16);// 2007-10-30 09:30

2.得到前一天的時間 

Calendar   c   =   Calendar.getInstance();
c.add(Calendar.DAY_OF_MONTH, -1);
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String mDateTime=formatter.format(c.getTime());
String strStart=mDateTime.substring(0, 16);//2007-10-29 09:30

3.得到前幾天的時間 

Calendar   c   =   Calendar.getInstance();
c.add(Calendar.DAY_OF_MONTH, -5);//得到前5
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String mDateTime=formatter.format(c.getTime());
String strStart=mDateTime.substring(0, 16);//2007-10-24 09:30

4.得到當前時間的前幾年的時間 

Calendar   c   =   Calendar.getInstance();
  c.add(Calendar.YEAR, -5);//得到前5年
  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
  String mDateTime=formatter.format(c.getTime());
  String strStart=mDateTime.substring(0, 16);//2002-10-24 09:30