java中获取日期和时间的方法总结

时间：2021-05-10 21:26:37

1、获取当前时间，和某个时间进行比较。此时主要拿long型的时间值。
 方法如下： 
 要使用 java.util.Date 。获取当前时间的代码如下

Date date = new Date();

date.getTime() ;

还有一种方式，使用 System.currentTimeMillis() ;
都是得到一个当前的时间的long型的时间的毫秒值，这个值实际上是当前时间值与1970年一月一号零时零分零秒相差的毫秒数

一、获取当前时间,   格式为:   yyyy-mm-dd   hh-mm-ss

DateFormat.getDateTimeInstance(2, 2, Locale.CHINESE).format(new java.util.Date());

二、获取当前时间,   格式为:   yyyy年mm月dd日   上午/下午hh时mm分ss秒

DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG, Locale.CHINESE).format(new java.util.Date());

三、获取当前时间(精确到毫秒),   格式为:   yyyy-mm-dd   hh:mm:ss.nnn

 new java.sql.Timestamp(System.currentTimeMillis()).toString();

一. 获取当前系统时间和日期并格式化输出:

 import java.util.Date;

 import java.text.SimpleDateFormat;

 public class NowString {

 public static void main(String[] args) {

 SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");//设置日期格式

 System.out.println(df.format(new Date()));// new Date()为获取当前系统时间

 }

 }

二. 在数据库里的日期只以年-月-日的方式输出，可以用下面两种方法：

1、用convert()转化函数：

String sqlst = "select convert(varchar(10),bookDate,126) as convertBookDate from roomBook where bookDate between '2007-4-10' and '2007-4-25'";

System.out.println(rs.getString("convertBookDate"));

2、利用SimpleDateFormat类：

先要输入两个java包：

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

然后：

定义日期格式：SimpleDateFormat sdf = new SimpleDateFormat(yy-MM-dd);

sql语句为：String sqlStr = "select bookDate from roomBook where bookDate between '2007-4-10' and '2007-4-25'";

输出：

System.out.println(df.format(rs.getDate("bookDate")));

3、java中获取当前日期和时间的方法

1)如何取得年月日、小时分秒？
2)如何取得从1970 年到现在的毫秒数？
3)如何取得某个日期是当月的最后一天？
4)如何格式化日期？

 import java.sql.Date;

 import java.text.SimpleDateFormat;

 import java.util.Calendar;

 public class Demo12 {

     /**

      * @param args

      */

     public static void main(String[] args) {

         // TODO Auto-generated method stub

         Calendar c = Calendar.getInstance();

         System.out.println("年：" + c.get(Calendar.YEAR));

         System.out.println("月：" + (c.get(Calendar.MONTH) + 1));

         System.out.println("日：" + c.get(Calendar.DAY_OF_MONTH));

         System.out.println("24时制小时：" + c.get(Calendar.HOUR_OF_DAY));

         System.out.println("12时制：" + c.get(Calendar.HOUR));

         System.out.println("分：" + c.get(Calendar.MINUTE));

         System.out.println("秒：" + c.get(Calendar.SECOND));

         System.out.println("今天是一年中的第：" + c.get(Calendar.DAY_OF_YEAR) + "天");

         //-------毫秒数

         long currentSec = System.currentTimeMillis();

         System.out.println("毫秒数为：" + currentSec);

         //------日期最后一天

                      int maxDay = c.getActualMaximum(Calendar.DAY_OF_MONTH);

                       System.out.println("当前日期最后一天：" + maxDay);

         //-------格式化日期

                     String format = "yyyy年MM月dd日 HH:mm:ss";

                     SimpleDateFormat SDF = new SimpleDateFormat(format);

                    String timer = SDF.format(new Date(currentSec));

                    System.out.println("格式化日期后：" + timer);

     }

 }

二

 import java.util.Date;

 import java.util.Calendar;

 import java.text.SimpleDateFormat;

 public class TestDate{

 public static void main(String[] args){

 Date now = new Date();

 SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy/MM/dd HH:mm:ss");//可以方便地修改日期格式

 String hehe = dateFormat.format( now );

 System.out.println(hehe);

 Calendar c = Calendar.getInstance();//可以对每个时间域单独修改

 int year = c.get(Calendar.YEAR);

 int month = c.get(Calendar.MONTH);

 int date = c.get(Calendar.DATE);

 int hour = c.get(Calendar.HOUR_OF_DAY);

 int minute = c.get(Calendar.MINUTE);

 int second = c.get(Calendar.SECOND);

 System.out.println(year + "/" + month + "/" + date + " " +hour + ":" +minute + ":" + second);

 }

 }

  有时候要把String类型的时间转换为Date类型，通过以下的方式，就可以将你刚得到的时间字符串转换为Date类型了。

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 java.util.Date time=null;

 try {

    time= sdf.parse(sdf.format(new Date()));

 } catch (ParseException e) {

    e.printStackTrace();

 }

一个不错日期时间类

 package com.wondersgroup.cc.cti;

 import java.sql.Timestamp;

 import java.util.Calendar;

 import java.util.Date;

 public class TestGetSystemTime {

  static Date nowTime = null;

  /**

  * @param args

  */

  public static void main(String[] args) {

   // 以下为 Clendar 测试代码

   int yyyy, mm, dd;

   Calendar c = Calendar.getInstance();

   yyyy = c.get(Calendar.YEAR);

   mm = c.get(Calendar.MONTH) + 1;

   dd = c.get(Calendar.DAY_OF_MONTH);

   System.out.println("year = "+yyyy);

   System.out.println("month = "+mm);

   System.out.println("day = "+dd);

   // 1. System.currentTimeMillis() 获取系统时间的代码

   Timestamp ts = new Timestamp(System.currentTimeMillis());

   String dateStr1 = ts.toString();

   System.out.println("System.currentTimeMillis() = "+dateStr1);

   // 2. date 为获得系统时间的另外一种方法

   Date date = new Date();

   String dateStr2 = new Timestamp(date.getTime()).toString();

   System.out.println(dateStr2);

   // 得到JAVA运行环境的一些基本属性

   System.getProperties().list(System.out);

  }

 }

一个完整的获取日期实例

格式化日期 String-->Date  或者 Data-->String
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");   
Date  date = sdf.parse("2009-11-04");//String-->Date   
String  sdate  = sdf.format(date );// Data-->String

 package com.hefeng.test;

 import java.text.DateFormat;

 import java.text.ParsePosition;

 import java.text.SimpleDateFormat;

 import java.util.Calendar;

 import java.util.Date;

 import java.util.GregorianCalendar;

 public class TimeTest {

 //用来全局控制 上一周，本周，下一周的周数变化

 private int weeks = 0;

 private int MaxDate;//一月最大天数

 private int MaxYear;//一年最大天数

 /**

 * @param args

 */

 public static void main(String[] args) {

 TimeTest tt = new TimeTest();

 System.out.println("得到6个月后的日期:"+tt .getAfterMonth(6);

 System.out.println("获取当天日期:"+tt.getNowTime("yyyy-MM-dd"));

 System.out.println("获取本周一日期:"+tt.getMondayOFWeek());

 System.out.println("获取本周日的日期~:"+tt.getCurrentWeekday());

 System.out.println("获取上周一日期:"+tt.getPreviousWeekday());

 System.out.println("获取上周日日期:"+tt.getPreviousWeekSunday());

 System.out.println("获取下周一日期:"+tt.getNextMonday());

 System.out.println("获取下周日日期:"+tt.getNextSunday());

 System.out.println("获得相应周的周六:"+tt.getNowTime("yyyy-MM-dd"));

 System.out.println("获取本月第一天日期:"+tt.getFirstDayOfMonth());

 System.out.println("获取本月最后一天日期:"+tt.getDefaultDay());

 System.out.println("获取上月第一天日期:"+tt.getPreviousMonthFirst());

 System.out.println("获取上月最后一天的日期:"+tt.getPreviousMonthEnd());

 System.out.println("获取下月第一天日期:"+tt.getNextMonthFirst());

 System.out.println("获取下月最后一天日期:"+tt.getNextMonthEnd());

 System.out.println("获取本年的第一天日期:"+tt.getCurrentYearFirst());

 System.out.println("获取本年最后一天日期:"+tt.getCurrentYearEnd());

 System.out.println("获取去年的第一天日期:"+tt.getPreviousYearFirst());

 System.out.println("获取去年的最后一天日期:"+tt.getPreviousYearEnd());

 System.out.println("获取明年第一天日期:"+tt.getNextYearFirst());

 System.out.println("获取明年最后一天日期:"+tt.getNextYearEnd());

 System.out.println("获取本季度第一天到最后一天:"+tt.getThisSeasonTime(11));

 System.out.println("获取两个日期之间间隔天数2008-12-1~2008-

 .29:"+TimeTest.getTwoDay("2008-12-1","2008-9-29"));

 }

 /**

 * 得到指定月后（前）的日期 参数传负数即可

 */

 public static String  getAfterMonth(int month) {

         Calendar c = Calendar.getInstance();//获得一个日历的实例

         SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");

         Date date = null;

         try{

             date = sdf.parse("2009-11-04");//初始日期

         }catch(Exception e){

         }

         c.setTime(date);//设置日历时间

         c.add(Calendar.MONTH,month);//在日历的月份上增加6个月

         String strDate = sdf.format(c.getTime()));//的到你想要得6个月后的日期

         return strDate;

  }

 /**

 * 得到二个日期间的间隔天数

 */

 public static String getTwoDay(String sj1, String sj2) {

 SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");

 long day = 0;

 try {

 java.util.Date date = myFormatter.parse(sj1);

 java.util.Date mydate = myFormatter.parse(sj2);

 day = (date.getTime() - mydate.getTime()) / (24 * 60 * 60 * 1000);

 } catch (Exception e) {

 return "";

 }

 return day + "";

 }

 /**

 * 根据一个日期，返回是星期几的字符串

 */

 public static String getWeek(String sdate) {

 // 再转换为时间

 Date date = TimeTest.strToDate(sdate);

 Calendar c = Calendar.getInstance();

 c.setTime(date);

 // int hour=c.get(Calendar.DAY_OF_WEEK);

 // hour 中存的就是星期几了，其范围 1~7

 // 1=星期日 7=星期六，其他类推

 return new SimpleDateFormat("EEEE").format(c.getTime());

 }

 /**

 * 将短时间格式字符串转换为时间 yyyy-MM-dd

 */

 public static Date strToDate(String strDate) {

 SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");

 ParsePosition pos = new ParsePosition(0);

 Date strtodate = formatter.parse(strDate, pos);

 return strtodate;

 }

 /**

 * 两个时间之间的天数

 *

 * @param date1

 * @param date2

 * @return

 */

 public static long getDays(String date1, String date2) {

 if (date1 == null || date1.equals(""))

 return 0;

 if (date2 == null || date2.equals(""))

 return 0;

 // 转换为标准时间

 SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");

 java.util.Date date = null;

 java.util.Date mydate = null;

 try {

 date = myFormatter.parse(date1);

 mydate = myFormatter.parse(date2);

 } catch (Exception e) {

 }

 long day = (date.getTime() - mydate.getTime()) / (24 * 60 * 60 * 1000);

 return day;

 }

 // 计算当月最后一天,返回字符串

 public String getDefaultDay(){

 String str = "";

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 Calendar lastDate = Calendar.getInstance();

 lastDate.set(Calendar.DATE,1);//设为当前月的1 号

 lastDate.add(Calendar.MONTH,1);//加一个月，变为下月的1 号

 lastDate.add(Calendar.DATE,-1);//减去一天，变为当月最后一天

 str=sdf.format(lastDate.getTime());

 return str;

 }

 // 上月第一天

 public String getPreviousMonthFirst(){

 String str = "";

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 Calendar lastDate = Calendar.getInstance();

 lastDate.set(Calendar.DATE,1);//设为当前月的1 号

 lastDate.add(Calendar.MONTH,-1);//减一个月，变为下月的1 号

 //lastDate.add(Calendar.DATE,-1);//减去一天，变为当月最后一天

 str=sdf.format(lastDate.getTime());

 return str;

 }

 //获取当月第一天

 public String getFirstDayOfMonth(){

 String str = "";

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 Calendar lastDate = Calendar.getInstance();

 lastDate.set(Calendar.DATE,1);//设为当前月的1 号

 str=sdf.format(lastDate.getTime());

 return str;

 }

 // 获得本周星期日的日期

 public String getCurrentWeekday() {

 weeks = 0;

 int mondayPlus = this.getMondayPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE, mondayPlus+6);

 Date monday = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preMonday = df.format(monday);

 return preMonday;

 }

 //获取当天时间

 public String getNowTime(String dateformat){

 Date now = new Date();

 SimpleDateFormat dateFormat = new SimpleDateFormat(dateformat);//可

 以方便

 地修改日期格式

 String hehe = dateFormat.format(now);

 return hehe;

 }

 // 获得当前日期与本周日相差的天数

 private int getMondayPlus() {

 Calendar cd = Calendar.getInstance();

 // 获得今天是一周的第几天，星期日是第一天，星期二是第二天......

 int dayOfWeek = cd.get(Calendar.DAY_OF_WEEK)-1; //因为按中国礼拜一

 作为第一

 天所以这里减1

 if (dayOfWeek == 1) {

 return 0;

 } else {

 return 1 - dayOfWeek;

 }

 }

 //获得本周一的日期

 public String getMondayOFWeek(){

 weeks = 0;

 int mondayPlus = this.getMondayPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE, mondayPlus);

 Date monday = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preMonday = df.format(monday);

 return preMonday;

 }

 //获得相应周的周六的日期

 public String getSaturday() {

 int mondayPlus = this.getMondayPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE, mondayPlus + 7 * weeks + 6);

 Date monday = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preMonday = df.format(monday);

 return preMonday;

 }

 // 获得上周星期日的日期

 public String getPreviousWeekSunday() {

 weeks=0;

 weeks--;

 int mondayPlus = this.getMondayPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE, mondayPlus+weeks);

 Date monday = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preMonday = df.format(monday);

 return preMonday;

 }

 // 获得上周星期一的日期

 public String getPreviousWeekday() {

 weeks--;

 int mondayPlus = this.getMondayPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE, mondayPlus + 7 * weeks);

 Date monday = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preMonday = df.format(monday);

 return preMonday;

 }

 // 获得下周星期一的日期

 public String getNextMonday() {

 weeks++;

 int mondayPlus = this.getMondayPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE, mondayPlus + 7);

 Date monday = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preMonday = df.format(monday);

 return preMonday;

 }

 // 获得下周星期日的日期

 public String getNextSunday() {

 int mondayPlus = this.getMondayPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE, mondayPlus + 7+6);

 Date monday = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preMonday = df.format(monday);

 return preMonday;

 }

 private int getMonthPlus(){

 Calendar cd = Calendar.getInstance();

 int monthOfNumber = cd.get(Calendar.DAY_OF_MONTH);

 cd.set(Calendar.DATE, 1);//把日期设置为当月第一天

 cd.roll(Calendar.DATE, -1);//日期回滚一天，也就是最后一天

 MaxDate=cd.get(Calendar.DATE);

 if(monthOfNumber == 1){

 return -MaxDate;

 }else{

 return 1-monthOfNumber;

 }

 }

 //获得上月最后一天的日期

 public String getPreviousMonthEnd(){

 String str = "";

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 Calendar lastDate = Calendar.getInstance();

 lastDate.add(Calendar.MONTH,-1);//减一个月

 lastDate.set(Calendar.DATE, 1);//把日期设置为当月第一天

 lastDate.roll(Calendar.DATE, -1);//日期回滚一天，也就是本月最后一天

 str=sdf.format(lastDate.getTime());

 return str;

 }

 //获得下个月第一天的日期

 public String getNextMonthFirst(){

 String str = "";

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 Calendar lastDate = Calendar.getInstance();

 lastDate.add(Calendar.MONTH,1);//减一个月

 lastDate.set(Calendar.DATE, 1);//把日期设置为当月第一天

 str=sdf.format(lastDate.getTime());

 return str;

 }

 //获得下个月最后一天的日期

 public String getNextMonthEnd(){

 String str = "";

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 Calendar lastDate = Calendar.getInstance();

 lastDate.add(Calendar.MONTH,1);//加一个月

 lastDate.set(Calendar.DATE, 1);//把日期设置为当月第一天

 lastDate.roll(Calendar.DATE, -1);//日期回滚一天，也就是本月最后一天

 str=sdf.format(lastDate.getTime());

 return str;

 }

 //获得明年最后一天的日期

 public String getNextYearEnd(){

 String str = "";

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 Calendar lastDate = Calendar.getInstance();

 lastDate.add(Calendar.YEAR,1);//加一个年

 lastDate.set(Calendar.DAY_OF_YEAR, 1);

 lastDate.roll(Calendar.DAY_OF_YEAR, -1);

 str=sdf.format(lastDate.getTime());

 return str;

 }

 //获得明年第一天的日期

 public String getNextYearFirst(){

 String str = "";

 SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");

 Calendar lastDate = Calendar.getInstance();

 lastDate.add(Calendar.YEAR,1);//加一个年

 lastDate.set(Calendar.DAY_OF_YEAR, 1);

 str=sdf.format(lastDate.getTime());

 return str;

 }

 //获得本年有多少天

 private int getMaxYear(){

 Calendar cd = Calendar.getInstance();

 cd.set(Calendar.DAY_OF_YEAR,1);//把日期设为当年第一天

 cd.roll(Calendar.DAY_OF_YEAR,-1);//把日期回滚一天。

 int MaxYear = cd.get(Calendar.DAY_OF_YEAR);

 return MaxYear;

 }

 private int getYearPlus(){

 Calendar cd = Calendar.getInstance();

 int yearOfNumber = cd.get(Calendar.DAY_OF_YEAR);//获得当天是一年中的第几天

 cd.set(Calendar.DAY_OF_YEAR,1);//把日期设为当年第一天

 cd.roll(Calendar.DAY_OF_YEAR,-1);//把日期回滚一天。

 int MaxYear = cd.get(Calendar.DAY_OF_YEAR);

 if(yearOfNumber == 1){

 return -MaxYear;

 }else{

 return 1-yearOfNumber;

 }

 }

 //获得本年第一天的日期

 public String getCurrentYearFirst(){

 int yearPlus = this.getYearPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE,yearPlus);

 Date yearDay = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preYearDay = df.format(yearDay);

 return preYearDay;

 }

 //获得本年最后一天的日期 *

 public String getCurrentYearEnd(){

 Date date = new Date();

 SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy");//可以方

 便地修

 改日期格式

 String years = dateFormat.format(date);

 return years+"-12-31";

 }

 //获得上年第一天的日期 *

 public String getPreviousYearFirst(){

 Date date = new Date();

 SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy");//可以方

 便地修

 改日期格式

 String years = dateFormat.format(date); int years_value = Integer.parseInt

 (years);

 years_value--;

 return years_value+"-1-1";

 }

 //获得上年最后一天的日期

 public String getPreviousYearEnd(){

 weeks--;

 int yearPlus = this.getYearPlus();

 GregorianCalendar currentDate = new GregorianCalendar();

 currentDate.add(GregorianCalendar.DATE,yearPlus+MaxYear*weeks+(MaxYear-1));

 Date yearDay = currentDate.getTime();

 DateFormat df = DateFormat.getDateInstance();

 String preYearDay = df.format(yearDay);

 getThisSeasonTime(11);

 return preYearDay;

 }

 //获得本季度

 public String getThisSeasonTime(int month){

 int array[][] = {{1,2,3},{4,5,6},{7,8,9},{10,11,12}};

 int season = 1;

 if(month>=1&&month<=3){

 season = 1;

 }

 if(month>=4&&month<=6){

 season = 2;

 }

 if(month>=7&&month<=9){

 season = 3;

 }

 if(month>=10&&month<=12){

 season = 4;

 }

 int start_month = array[season-1][0];

 int end_month = array[season-1][2];

 Date date = new Date();

 SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy");//可以方便地修改日期格式

 String years = dateFormat.format(date);

 int years_value = Integer.parseInt(years);

 int start_days =1;//years+"-"+String.valueOf(start_month)+"-

 ";//getLastDayOfMonth(years_value,start_month);

 int end_days = getLastDayOfMonth(years_value,end_month);

 String seasonDate =

 years_value+"-"+start_month+"-"+start_days+";"+years_value+"-"+end_month+"-"+end_days;

 return seasonDate;

 }

 /**

 * 获取某年某月的最后一天

 * @param year 年

 * @param month 月

 * @return 最后一天

 */

 private int getLastDayOfMonth(int year, int month) {

 if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8

 || month == 10 || month == 12) {

 return 31;

 }

 if (month == 4 || month == 6 || month == 9 || month == 11) {

 return 30;

 }

 if (month == 2) {

 if (isLeapYear(year)) {

 return 29;

 } else {

 return 28;

 }

 }

 return 0;

 }

 /**

 * 是否闰年

 * @param year 年

 * @return

 */

 public boolean isLeapYear(int year) {

 return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);

 }

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