java中获取日期和时间的方法总结

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);
 }