Date用法一例

package test;

import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Test1 {
	public static void main(String[] args) {
		long time = new Date().getTime();
		System.out.println(time);
		System.out.println(System.currentTimeMillis());
		Timestamp timestamp = new Timestamp(time);
		System.out.println(timestamp);
		
		Calendar cal = Calendar.getInstance();
		cal.set(2001, 1, 20);
		System.out.println(cal.getTime());
		cal.setTime(new Date());
		System.out.println(cal.get(Calendar.YEAR));
		System.out.println(cal.get(Calendar.MONTH));
		System.out.println(cal.get(Calendar.DATE));
		
		SimpleDateFormat format = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");
		System.out.println(format.format(new Date()));

	}
}

import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class TestDate {
	public static void main(String[]args){
		Calendar   cal   =   Calendar.getInstance(); 
        cal.set(   2000,   1,   21   ); 
        int   max   =   cal.getActualMaximum(Calendar.DAY_OF_MONTH); 
        System.out.println(max);
        
        cal.add(Calendar.MONTH, -12);
        Date date = cal.getTime();
        SimpleDateFormat sdf = new SimpleDateFormat("yyyyMMdd-HH:mm:ss");
        
        System.out.println(sdf.format(date));
	}
}