package pack;import java.text.SimpleDateFormat;import java.util.Date;public class Demo {	/**	 * @param args	 */	public static void main(String[] args) {		// TODO Auto-generated method stub		Date date = new Date();		System.out.println(date);
　　　　　　　　　//按照格式化输出时间		SimpleDateFormat sd = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");		String format = sd.format(date);		System.out.println(format);	}}

package pack;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;public class Demo {	/**	 * @param args	 */	public static void main(String[] args) {		// TODO Auto-generated method stub		//获取实例		Calendar c = Calendar.getInstance();		System.out.println(c);				Date time = c.getTime();		System.out.println(time);				//设置calendar日期时间		c.set(2015, 07, 15);		time = c.getTime();		System.out.println(time);				//增加3个月		c.add(Calendar.DAY_OF_MONTH, 3);		time = c.getTime();		System.out.println(time);	}}

package pack;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;/** * @Description TODO 打印最近3天的时间 * @author WiKi * @date 2014-11-29 上午11:31:25 */public class Demo {	/**	 * Calendar日期类   这个类可以把时间设置在任意时刻	 * 查询最近三天的记录	 */	public static void main(String[] args) {		Calendar c = Calendar.getInstance();		Date nowtime;				c.set(2015, 06, 25, 12, 20);		nowtime = c.getTime();				SimpleDateFormat sd = new SimpleDateFormat("yyyy-M-d HH:mm:ss E");		System.out.println(sd.format(nowtime));				c.add(Calendar.DAY_OF_MONTH, -3);		System.out.println(sd.format(c.getTime()));	}}