【Java学习】日期格式

1.1 返回时间类型 yyyy-MM-dd HH:mm:ss

public static Date getNowDate() {

   Date currentTime = new Date();

   SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

   String dateString = formatter.format(currentTime);

   ParsePosition pos = new ParsePosition(8);

   Date currentTime_2 = formatter.parse(dateString, pos);

   return currentTime_2;

}

1.2 返回短时间格式 yyyy-MM-dd

  

DateFormat format1 = new SimpleDateFormat("yyyy-MM-dd");         

DateFormat format 2= new SimpleDateFormat("yyyy年MM月dd日 HH时mm分ss秒");         

Date date = null;   

String str = null;                  

            

// String转Date   

str = "2007-1-18";         

try {   

           date = format1.parse(str);   

           data = format2.parse(str);

} catch (ParseException e) {   

           e.printStackTrace();   

}   

1.3 返回字符串格式 yyyy-MM-dd HH:mm:ss

  

public static String getStringDate() {

   Date currentTime = new Date();

   SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

   String dateString = formatter.format(currentTime);

   return dateString;

}

1.4 返回短时间字符串格式yyyy-MM-dd

public static String getStringDateShort() {

   Date currentTime = new Date();

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

   String dateString = formatter.format(currentTime);

   return dateString;

}

1.5 获取时间 小时:分;秒 HH:mm:ss

  

public static String getTimeShort() {

   SimpleDateFormat formatter = new SimpleDateFormat("HH:mm:ss");

   Date currentTime = new Date();

   String dateString = formatter.format(currentTime);

   return dateString;

}

1.6 将长时间格式字符串转换为时间 yyyy-MM-dd HH:mm:ss

public static Date strToDateLong(String strDate) {

   SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

   ParsePosition pos = new ParsePosition(0);

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

   return strtodate;

}

1.7 将长时间格式时间转换为字符串 yyyy-MM-dd HH:mm:ss

public static String dateToStrLong(java.util.Date dateDate) {

   SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

   String dateString = formatter.format(dateDate);

   return dateString;

}

1.8 将短时间格式时间转换为字符串 yyyy-MM-dd

  

public static String dateToStr(java.util.Date dateDate) {

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

   String dateString = formatter.format(dateDate);

   return dateString;

}

1.9 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;

}

1.10 得到现在时间

public static Date getNow() {

   Date currentTime = new Date();

   return currentTime;

}

1.11 提取一个月中的最后一天

  

public static Date getLastDate(long day) {

   Date date = new Date();

   long date_3_hm = date.getTime() - 3600000 * 34 * day;

   Date date_3_hm_date = new Date(date_3_hm);

   return date_3_hm_date;

}

1.12 字符串 yyyyMMdd HHmmss

public static String getStringToday() {

   Date currentTime = new Date();

   SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd HHmmss");

   String dateString = formatter.format(currentTime);

   return dateString;

}

1.13 得到现在小时

public static String getHour() {

   Date currentTime = new Date();

   SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

   String dateString = formatter.format(currentTime);

   String hour;

   hour = dateString.substring(11, 13);

   return hour;

}

1.14 得到现在分钟

public static String getTime() {

   Date currentTime = new Date();

   SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

   String dateString = formatter.format(currentTime);

   String min;

   min = dateString.substring(14, 16);

   return min;

}

1.15 根据用户传入的时间表示格式，返回当前时间的格式

如果是yyyyMMdd，注意字母y不能大写。

public static String getUserDate(String sformat) {

   Date currentTime = new Date();

   SimpleDateFormat formatter = new SimpleDateFormat(sformat);

   String dateString = formatter.format(currentTime);

   return dateString;

}

--------------------------------------------------------------------------------------------------------------------------------

二、做成方法2.1返回时间类型 yyyy-MM-dd HH:mm:ss

public static Date getNowDate() {

  Date currentTime = new Date();

  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

  String dateString = formatter.format(currentTime);

  ParsePosition pos = new ParsePosition(8);

  Date currentTime_2 = formatter.parse(dateString, pos);

  return currentTime_2;

}

2.2返回短时间格式 yyyy-MM-dd

public static Date getNowDateShort() {

  Date currentTime = new Date();

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

  String dateString = formatter.format(currentTime);

  ParsePosition pos = new ParsePosition(8);

  Date currentTime_2 = formatter.parse(dateString, pos);

  return currentTime_2;

}

2.3返回字符串格式 yyyy-MM-dd HH:mm:ss

public static String getStringDate() {

  Date currentTime = new Date();

  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

  String dateString = formatter.format(currentTime);

  return dateString;

}

2.4返回短时间字符串格式yyyy-MM-dd

public static String getStringDateShort() {

  Date currentTime = new Date();

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

  String dateString = formatter.format(currentTime);

  return dateString;

}

2.5小时:分;秒 HH:mm:ss

public static String getTimeShort() {

  SimpleDateFormat formatter = new SimpleDateFormat("HH:mm:ss");

  Date currentTime = new Date();

  String dateString = formatter.format(currentTime);

  return dateString;

}

2.6将长时间格式字符串转换为时间 yyyy-MM-dd HH:mm:ss

public static Date strToDateLong(String strDate) {

  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

  ParsePosition pos = new ParsePosition(0);

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

  return strtodate;

}

2.7将长时间格式时间转换为字符串 yyyy-MM-dd HH:mm:ss

public static String dateToStrLong(java.util.Date dateDate) {

  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

  String dateString = formatter.format(dateDate);

  return dateString;

}

2.8将短时间格式时间转换为字符串 yyyy-MM-dd

public static String dateToStr(java.util.Date dateDate) {

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

  String dateString = formatter.format(dateDate);

  return dateString;

}

2.9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;

}

2.10得到现在时间

  

public static Date getNow() {

  Date currentTime = new Date();

  return currentTime;

}

2.11提取一个月中的最后一天

public static Date getLastDate(long day) {

  Date date = new Date();

  long date_3_hm = date.getTime() - 3600000 * 34 * day;

  Date date_3_hm_date = new Date(date_3_hm);

  return date_3_hm_date;

}

2.12字符串 yyyyMMdd HHmmss

public static String getStringToday() {

  Date currentTime = new Date();

  SimpleDateFormat formatter = new SimpleDateFormat("yyyyMMdd HHmmss");

  String dateString = formatter.format(currentTime);

  return dateString;

}

2.13得到现在小时

  public static String getHour() {

  Date currentTime = new Date();

  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

  String dateString = formatter.format(currentTime);

  String hour;

  hour = dateString.substring(11, 13);

  return hour;

}

2.14得到现在分钟

public static String getTime() {

  Date currentTime = new Date();

  SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

  String dateString = formatter.format(currentTime);

  String min;

  min = dateString.substring(14, 16);

  return min;

}

2.15根据用户传入的时间表示格式，返回当前时间的格式

如果是yyyyMMdd，注意字母y不能大写。

public static String getUserDate(String sformat) {

  Date currentTime = new Date();

  SimpleDateFormat formatter = new SimpleDateFormat(sformat);

  String dateString = formatter.format(currentTime);

  return dateString;

}

2.16二个小时时间间的差值,必须保证二个时间都是"HH:MM"的格式，返回字符型的分钟

  

public static String getTwoHour(String st1, String st2) {

  String[] kk = null;

  String[] jj = null;

  kk = st1.split(":");

  jj = st2.split(":");

  if (Integer.parseInt(kk[0]) < Integer.parseInt(jj[0]))

   return "0";

  else {

   double y = Double.parseDouble(kk[0]) + Double.parseDouble(kk[1]) / 60;

   double u = Double.parseDouble(jj[0]) + Double.parseDouble(jj[1]) / 60;

   if ((y - u) > 0)

    return y - u + "";

   else

    return "0";

  }

}

2.17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 + "";

}

2.18时间前推或后推分钟,其中JJ表示分钟

public static String getPreTime(String sj1, String jj) {

  SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

  String mydate1 = "";

  try {

   Date date1 = format.parse(sj1);

   long Time = (date1.getTime() / 1000) + Integer.parseInt(jj) * 60;

   date1.setTime(Time * 1000);

   mydate1 = format.format(date1);

  } catch (Exception e) {

  }

  return mydate1;

}

2.19得到一个时间延后或前移几天的时间,nowdate为时间,delay为前移或后延的天数

  

public static String getNextDay(String nowdate, String delay) {

  try{

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

  String mdate = "";

  Date d = strToDate(nowdate);

  long myTime = (d.getTime() / 1000) + Integer.parseInt(delay) * 24 * 60 * 60;

  d.setTime(myTime * 1000);

  mdate = format.format(d);

  return mdate;

  }catch(Exception e){

   return "";

  }

}

2.20判断是否润年

public static boolean isLeapYear(String ddate) {

  /**

   * 详细设计： 1.被400整除是闰年，否则： 2.不能被4整除则不是闰年 3.能被4整除同时不能被100整除则是闰年

   * 3.能被4整除同时能被100整除则不是闰年

   */

  Date d = strToDate(ddate);

  GregorianCalendar gc = (GregorianCalendar) Calendar.getInstance();

  gc.setTime(d);

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

  if ((year % 400) == 0)

   return true;

  else if ((year % 4) == 0) {

   if ((year % 100) == 0)

    return false;

   else

    return true;

  } else

   return false;

}

2.21返回美国时间格式 26 Apr 2006

public static String getEDate(String str) {

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

  ParsePosition pos = new ParsePosition(0);

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

  String j = strtodate.toString();

  String[] k = j.split(" ");

  return k[2] + k[1].toUpperCase() + k[5].substring(2, 4);

}

2.22获取一个月的最后一天

public static String getEndDateOfMonth(String dat) {// yyyy-MM-dd

  String str = dat.substring(0, 8);

  String month = dat.substring(5, 7);

  int mon = Integer.parseInt(month);

  if (mon == 1 || mon == 3 || mon == 5 || mon == 7 || mon == 8 || mon == 10 || mon == 12) {

   str += "31";

  } else if (mon == 4 || mon == 6 || mon == 9 || mon == 11) {

   str += "30";

  } else {

   if (isLeapYear(dat)) {

    str += "29";

   } else {

    str += "28";

   }

  }

  return str;

}

2.23判断二个时间是否在同一个周

public static boolean isSameWeekDates(Date date1, Date date2) {

  Calendar cal1 = Calendar.getInstance();

  Calendar cal2 = Calendar.getInstance();

  cal1.setTime(date1);

  cal2.setTime(date2);

  int subYear = cal1.get(Calendar.YEAR) - cal2.get(Calendar.YEAR);

  if (0 == subYear) {

   if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR))

    return true;

  } else if (1 == subYear && 11 == cal2.get(Calendar.MONTH)) {

   // 如果12月的最后一周横跨来年第一周的话则最后一周即算做来年的第一周

   if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR))

    return true;

  } else if (-1 == subYear && 11 == cal1.get(Calendar.MONTH)) {

   if (cal1.get(Calendar.WEEK_OF_YEAR) == cal2.get(Calendar.WEEK_OF_YEAR))

    return true;

  }

  return false;

}

2.24产生周序列,即得到当前时间所在的年度是第几周

public static String getSeqWeek() {

  Calendar c = Calendar.getInstance(Locale.CHINA);

  String week = Integer.toString(c.get(Calendar.WEEK_OF_YEAR));

  if (week.length() == 1)

   week = "0" + week;

  String year = Integer.toString(c.get(Calendar.YEAR));

  return year + week;

}

2.25获得一个日期所在的周的星期几的日期

如要找出2002年2月3日所在周的星期一是几号

public static String getWeek(String sdate, String num) {

  // 再转换为时间

  Date dd = VeDate.strToDate(sdate);

  Calendar c = Calendar.getInstance();

  c.setTime(dd);

  if (num.equals("1")) // 返回星期一所在的日期

   c.set(Calendar.DAY_OF_WEEK, Calendar.MONDAY);

  else if (num.equals("2")) // 返回星期二所在的日期

   c.set(Calendar.DAY_OF_WEEK, Calendar.TUESDAY);

  else if (num.equals("3")) // 返回星期三所在的日期

   c.set(Calendar.DAY_OF_WEEK, Calendar.WEDNESDAY);

  else if (num.equals("4")) // 返回星期四所在的日期

   c.set(Calendar.DAY_OF_WEEK, Calendar.THURSDAY);

  else if (num.equals("5")) // 返回星期五所在的日期

   c.set(Calendar.DAY_OF_WEEK, Calendar.FRIDAY);

  else if (num.equals("6")) // 返回星期六所在的日期

   c.set(Calendar.DAY_OF_WEEK, Calendar.SATURDAY);

  else if (num.equals("0")) // 返回星期日所在的日期

   c.set(Calendar.DAY_OF_WEEK, Calendar.SUNDAY);

  return new SimpleDateFormat("yyyy-MM-dd").format(c.getTime());

}

2.26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 = VeDate.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());

}

public static String getWeekStr(String sdate){

  String str = "";

  str = VeDate.getWeek(sdate);

  if("1".equals(str)){

   str = "星期日";

  }else if("2".equals(str)){

   str = "星期一";

  }else if("3".equals(str)){

   str = "星期二";

  }else if("4".equals(str)){

   str = "星期三";

  }else if("5".equals(str)){

   str = "星期四";

  }else if("6".equals(str)){

   str = "星期五";

  }else if("7".equals(str)){

   str = "星期六";

  }

  return str;

}

2.27两个时间之间的天数

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;

}

2.28形成特殊的日历

        根据传入的一个时间返回一个结构 星期日 星期一 星期二 星期三 星期四 星期五 星期六 下面是当月的各个时间

  此函数返回该日历第一行星期日所在的日期

public static String getNowMonth(String sdate) {

  // 取该时间所在月的一号

  sdate = sdate.substring(0, 8) + "01";

  // 得到这个月的1号是星期几

  Date date = VeDate.strToDate(sdate);

  Calendar c = Calendar.getInstance();

  c.setTime(date);

  int u = c.get(Calendar.DAY_OF_WEEK);

  String newday = VeDate.getNextDay(sdate, (1 - u) + "");

  return newday;

}

2.29取得数据库主键 生成格式为yyyymmddhhmmss+k位随机数

public static String getNo(int k) {

  return getUserDate("yyyyMMddhhmmss") + getRandom(k);

}

package com.company.dateTime;

import java.util.Calendar;
import java.util.Date;
import java.text.SimpleDateFormat;
/**
 * @author 
 * @date 2020/10/25 16:06
 * @project
 */
public class TestCalendar {
    public static void main(String[] args) {
        Calendar c = Calendar.getInstance();
        int day = c.get(Calendar.DATE);
        int month = c.get(Calendar.MONTH) + 1;
        int year = c.get(Calendar.YEAR);
        int dom =  c.get(Calendar.DAY_OF_MONTH);
        int dow = c.get(Calendar.DAY_OF_WEEK);
        int doy = c.get(Calendar.DAY_OF_YEAR);
        System.out.println("day = " + day);
        System.out.println("month = " + month);
        System.out.println("year = " + year);
        System.out.println("dom = " + dom);
        System.out.println("dow = " + dow);
        System.out.println("doy = " + doy);
        System.out.println("currentTimeMillis = " + System.currentTimeMillis());
        System.out.println("c.getTime() = " + c.getTime());
        //实现当前日期+1天
        c.setTime(new Date());
        c.add(Calendar.DAY_OF_MONTH, -1);
        Date endTime = c.getTime();
        System.out.println("endTime = " + endTime);
        SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
        System.out.println("sdf.format(endTime) = " + sdf.format(endTime));


    }
}

package com.company.dateTime;

import java.text.ParseException;
import java.util.Date;
import java.text.SimpleDateFormat;
/**
 * @author 
 * @date 2020/10/25 16:36
 * @project 利用生日获取当前的年龄
 */
public class TestSimpleDateFormatParse {
    public static void main(String[] args) throws ParseException {
        String stringFormat = "yyyy年MM月dd日";
        SimpleDateFormat sdf = new SimpleDateFormat(stringFormat);
        String birthday = "1995年05月02日";
        Date d = sdf.parse(birthday);
        long myTime = d.getTime();
        long currentTime = new Date().getTime();
        System.out.println("(currentTime - myTime)/1000/60/60/24/365 = " + (currentTime - myTime)/1000/60/60/24/365);
        Long s = Long.parseLong("1233");
        System.out.println("s = " + s);
        char[] c = new char[]{'a', 'b', 'c'};
        System.out.println("String.valueOf(c) = " + String.valueOf(c));


    }
}

package com.company.dateTime;

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

/**
 * @author 
 * @date 2020/10/25 16:40
 * @project Java 实例 - 格式化时间（SimpleDateFormat）
 */
public class TestSimpleDateFormat {
    public static void main(String[] args) {
        Date date = new Date();
        String strDateFormat = "yyyy-MM-DD HH:mm:ss";
        SimpleDateFormat sdf = new SimpleDateFormat(strDateFormat);
        System.out.println("sdf.format(date) = " + sdf.format(date));
        System.out.println("date.getTime() = " + date.getTime());
    }
}