1.系统时间

package com.yfs.javase;import java.sql.Time;import java.sql.Timestamp;import java.util.Calendar;import java.util.Date;public class DateDemo1 {	/**	 * 时间表示法	 */	public static void main(String[] args) {		// long表示法		long now = System.currentTimeMillis();//获取系统时间毫秒值		System.out.println("计算机时间: " + now);		//date表示法		Date date = new Date();		System.out.println("util.Date : " + date);		//子类		java.sql.Date sDate = new java.sql.Date(now);		System.out.println("sql.Date : " + sDate);		Time time = new Time(now);		System.out.println("time : " + time);		Timestamp ts = new Timestamp(now);		System.out.println("timestamp : " + ts);				//calendar表示法		Calendar cal = Calendar.getInstance();//获取实例		System.out.println(cal.getClass().getName());		System.out.println(cal);			}}

 2.Date类

package com.yfs.javase;import java.sql.Time;import java.sql.Timestamp;import java.util.Calendar;import java.util.Date;public class DateDemo2 {	/**	 * date类	 */	public static void main(String[] args) {		Date date = new Date();//系统时间		System.out.println("util.Date : " + date);//		Date d2 = new Date(2014,6,15);//已过时//		System.out.println("d2 : " + d2);				Date d3 = new Date(System.currentTimeMillis() - 1000 * 60 * 60);		System.out.println("d3 : " + d3);				System.out.println("d3.before(date) : " + d3.before(date));		System.out.println("d3.after(date) : " + d3.after(date));		System.out.println("d3.getTime() : " + d3.getTime());				}}

 3.calendar类

package com.yfs.javase;import java.sql.Time;import java.sql.Timestamp;import java.util.Calendar;import java.util.Date;public class DateDemo3 {	/**	 * calendar类	 */	public static void main(String[] args) {		Calendar cal = Calendar.getInstance();		//获取信息		int year = cal.get(Calendar.YEAR);		int month = cal.get(Calendar.MONTH) + 1;// 0 - 11   1 -12		int day = cal.get(Calendar.DATE);						System.out.println("year = " + year);		System.out.println("month = " + month);		System.out.println("day = " + day);		//System.out.println(Calendar.DATE);  星期日  1  - 7 		System.out.println("星期 ： " + cal.get(Calendar.DAY_OF_WEEK));		System.out.println("今年第几天 ： " + cal.get(Calendar.DAY_OF_YEAR));		System.out.println("星期四 ： " + Calendar.THURSDAY);				//设置//		cal.set(Calendar.YEAR, 2013);//		cal.set(Calendar.MONTH, 2);//		cal.set(Calendar.DATE, 15);//		//		cal.set(2015, 0, 31, 8, 30, 25);//		//		System.out.println("cal = " +  String.format("%tF  %

 4.日期格式化

package com.yfs.javase;import java.sql.Time;import java.sql.Timestamp;import java.util.Calendar;import java.util.Date;public class DateDemo4 {	/**	 * 格式化	 */	public static void main(String[] args) {		Date date = new Date();		System.out.println("date = " +  String.format("%tF  %tT", date,date));		Calendar cal = Calendar.getInstance();		System.out.println("cal = " +  String.format("%tF %

 5.格式化对象

package com.yfs.javase;import java.sql.Time;import java.sql.Timestamp;import java.text.DateFormat;import java.util.Calendar;import java.util.Date;public class DateDemo5 {	/**	 * 格式化	 */	public static void main(String[] args) {		Date date = new Date();		System.out.println("date = " + date);		//格式化对象		//DateFormat df = DateFormat.getDateInstance(DateFormat.FULL);		DateFormat df = DateFormat.getDateInstance(DateFormat.LONG);		//DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT);		System.out.println("实现类 ： " + df.getClass().getName());		System.out.println(df.format(date));				df = DateFormat.getTimeInstance(DateFormat.LONG);		System.out.println(df.format(date));				df = DateFormat.getDateTimeInstance(DateFormat.FULL, DateFormat.SHORT);		System.out.println(df.format(date));							}}

 6.SimpleDateFormat

package com.yfs.javase;import java.sql.Time;import java.sql.Timestamp;import java.text.DateFormat;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;public class DateDemo6 {	/**	 * 格式化	 */	public static void main(String[] args) {		Date date = new Date();		System.out.println("date = " + date);		//格式化对象		SimpleDateFormat  sdf = new SimpleDateFormat("yyyy@MM@dd  HH%mm%ss");		System.out.println(sdf.format(date));		sdf.applyPattern("dd日MM月yyyy年");		System.out.println(sdf.format(date));			}}

 7.日期对象转化

package com.yfs.javase;import java.sql.Time;import java.sql.Timestamp;import java.text.DateFormat;import java.text.SimpleDateFormat;import java.util.Calendar;import java.util.Date;public class DateDemo7 {	/**	 * 对象转化	 */	public static void main(String[] args) {		//long		Date ud = new Date();		//util.Date -> sql.Date		java.sql.Date sd = new java.sql.Date(ud.getTime());		//sql.Date -> util.Date 		ud.setTime(sd.getTime());				//util.Date -> Calendar		Calendar cal = Calendar.getInstance();		cal.setTime(ud);				//Calendar -> util.Date 		ud = cal.getTime();				String s = "2008-08-08";		//sd = s;		sd = java.sql.Date.valueOf(s);		System.out.println(sd);					}}