1.Calendar 转化 String
Calendar calendat = Calendar.getInstance();
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
String dateStr = sdf.format(calendar.getTime());

2.String 转化Calendar
String str="2012-5-27";
SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");
Date date =sdf.parse(str);
Calendar calendar = Calendar.getInstance();
calendar.setTime(date);

3.Date 转化String
SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");
String dateStr=sdf.format(new Date());

4.String 转化Date
String str="2012-5-27";
SimpleDateFormat sdf= new SimpleDateFormat("yyyy-MM-dd");
Date date= sdf.parse(str);

5.Date 转化Calendar
Calendar calendar = Calendar.getInstance();
calendar.setTime(new java.util.Date());

6.Calendar转化Date
Calendar calendar = Calendar.getInstance();
java.util.Date date =calendar.getTime();

7.String 转成 Timestamp
Timestamp ts = Timestamp.valueOf("2012-1-14 08:11:00");

8.Date 转 TimeStamp
SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
String time = df.format(new Date());
Timestamp ts = Timestamp.valueOf(time);