java新手笔记25 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 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);

}

}

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());

}

}

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));

}

}

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\n",123);//格式控制符
System.out.printf("%c\n",97);//格式控制符
//格式化方法
String result = String.format("%c", 65);
System.out.println("result = " + result );

}

}

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));

}

}

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));

}

}

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);

}

}