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 %<tT", cal));
//
//计算
cal.add(Calendar.DATE, -100);
System.out.println("cal = " + String.format("%tF", cal));
}
}
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 %<tT", cal));
//字符串格式化
System.out.printf("%d
",123);//格式控制符
System.out.printf("%c
",97);//格式控制符
//格式化方法
String result = String.format("%c", 65);
System.out.println("result = " + result );
}
}
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);
}
}