Java中获取日期函数应用

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（1）String类型转换成日期（Date类型）：

         SimpleDateFormat myFormatter = new SimpleDateFormat("yyyy-MM-dd");
         java.util.Date date = myFormatter.parse(sj1);
         java.util.Date mydate = myFormatter.parse(sj2);
    （2）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());
    }

   (3) 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;
    }

    (4) 两个时间之间的天数之差
    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;
    }
    （5）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;
    }


   （6）获取当天时间
        Date   now   =   new   Date();

    （7）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;
        }
    }

    （8）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;
    }

（9）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;
    }

（10）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;
    }

（11）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;
    }

   （12）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;
    }

（13）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;
    }

   （14）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;
    }

（15）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;
    }

（16）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;
    }

    （17）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;
    }

（18）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;

    }

（19）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;
    }
      }
（20）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;
    }


（21）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";
    }


（22）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";
    }

（23）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;
    }

（24）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)+"-1";//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;

    }
  （25）获取某年某月的最后一天
      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;
   }
   （26）是否闰年
   public boolean isLeapYear(int year) {
        return (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
}
-------------------------------

   （27）获取当前时间日期的字符串
    public static String getCurrentDateStr(DateFormatType dateFormatType) {
        Date date = getCurrentDate();
        return (String) OpearationDate(date, dateFormatType.getValue());
    }

    （28）时间、日期格式化成字符串
     public static String formatDate(Date date, DateFormatType dateFormatType) {
        return (String) OpearationDate(date, dateFormatType.getValue());
    }

    （29）从字符串解析成时间、日期
       public static Date parseDate(String dateStr, DateFormatType dateFormatType) {
        return (Date) OpearationDate(dateStr, dateFormatType.getValue());
    }

     （30）获取当前日期的年、月、日、时、分、秒
      public static int getCurrentTime(TimeFormatType timeFormatType) {
        return getTime(getCurrentDate(), timeFormatType);
    }
     （31）获取指定日期的年、月、日、时、分、秒
       public static int getTime(Date date, TimeFormatType timeFormatType) {
        try {
            Calendar c = Calendar.getInstance();
            c.setTime(date);
            int type = timeFormatType.getValue();
            int i = c.get(type);
            return type == 2 ? i + 1 : i;
        } catch (Exception e) {
            throw new RuntimeException("获取失败", e);
        }
    }

     （32）获取指定日期的毫秒数
     public static long getMillis(Date date) {
        java.util.Calendar c = java.util.Calendar.getInstance();
        c.setTime(date);
        return c.getTimeInMillis();
    }

     （33）日期月份相加、减操作
    public static Date operationDateOfMonth(Date date, int month, DateOperationType dateOperationType) {
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        c.add(Calendar.MONTH, dateOperationType.getValue() ? month : month - (month * 2));
        return c.getTime();
    }

    （34）日期天数相加、减操作
      public static Date operationDateOfDay(Date date, int day, DateOperationType dateOperationType) {
        Calendar c = Calendar.getInstance();
        c.setTime(date);
        long millis = c.getTimeInMillis();
        long millisOfday = day * 24 * 3600 * 1000;
        long sumMillis = dateOperationType.getValue() ? (millis + millisOfday) : (millis - millisOfday);
        c.setTimeInMillis(sumMillis);
        return c.getTime();
    }

  （35）将要格式化的日期字符串格式写成枚举类型
    public enum DateFormatType {
        /**
         * 格式为：yyyy-MM-dd HH:mm:ss
         */
        DATE_FORMAT_STR("yyyy-MM-dd HH:mm:ss"),
        /**
         * 格式为：yyyyMMddHHmmss
         */
        SIMPLE_DATE_TIME_FORMAT_STR("yyyyMMddHHmmss"),

        /**
         * 格式为：yyyy-MM-dd
         */
        SIMPLE_DATE_FORMAT_STR("yyyy-MM-dd"),

        /**
         * 格式为：yyyy/MM/dd
         */
        SIMPLE_DATE_FORMAT_VIRGULE_STR("yyyy/MM/dd"),

        /**
         * 格式为：HH:mm:ss
         */
        HOUR_MINUTE_SECOND("HH:mm:ss"),

        /**
         * 格式为：HH:mm
         */
        HOUR_MINUTE("HH:mm");

        private final String value;

        DateFormatType(String formatStr) {
            this.value = formatStr;
        }

        public String getValue() {
            return value;
        }
    }
}
（36）Calender 常用方法

<PRE class=java name="code">package com.iwode.common;

import java.text.DateFormat;
import java.text.ParsePosition;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;

/**
* 常用日历操作辅助类
*
* @author steven 2010-08-10
* @email:qing.tan@iwode.com
*/
public class CalendarUtil {

    private int weeks = 0;// 用来全局控制上一周，本周，下一周的周数变化
    private int MaxDate; // 一月最大天数
    private int MaxYear; // 一年最大天数

    /**
     * 测试
     *
     * @param args
     */
    public static void main(String[] args) {
        CalendarUtil tt = new CalendarUtil();
        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("获得相应周的周六的日期:" + 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:" + tt.getThisSeasonFirstTime(11));
        System.out.println("获取本季度最后一天:" + tt.getThisSeasonFinallyTime(11));
        System.out.println("获取两个日期之间间隔天数2008-12-1~2008-9.29:"
                + CalendarUtil.getTwoDay("2008-12-1", "2008-9-29"));
        System.out.println("获取当前月的第几周：" + tt.getWeekOfMonth());
        System.out.println("获取当前年份：" + tt.getYear());
        System.out.println("获取当前月份：" + tt.getMonth());
        System.out.println("获取今天在本年的第几天：" + tt.getDayOfYear());
        System.out.println("获得今天在本月的第几天(获得当前日)：" + tt.getDayOfMonth());
        System.out.println("获得今天在本周的第几天：" + tt.getDayOfWeek());
        System.out.println("获得半年后的日期："
                + tt.convertDateToString(tt.getTimeYearNext()));
    }

   （37）获得当前年份
    public static int getYear() {
        return Calendar.getInstance().get(Calendar.YEAR);
    }

    （38）获得当前月份
     public static int getMonth() {
        return Calendar.getInstance().get(Calendar.MONTH) + 1;
    }

    （39）获得今天在本年的第几天
    public static int getDayOfYear() {
        return Calendar.getInstance().get(Calendar.DAY_OF_YEAR);
    }

    （40）获得今天在本月的第几天(获得当前日)
    public static int getDayOfMonth() {
        return Calendar.getInstance().get(Calendar.DAY_OF_MONTH);
    }

    （41）获得今天在本周的第几天
     public static int getDayOfWeek() {
        return Calendar.getInstance().get(Calendar.DAY_OF_WEEK);
    }

    （42）获得今天是这个月的第几周
    public static int getWeekOfMonth() {
        return Calendar.getInstance().get(Calendar.DAY_OF_WEEK_IN_MONTH);
    }

   （43）获得半年后的日期
    public static Date getTimeYearNext() {
        Calendar.getInstance().add(Calendar.DAY_OF_YEAR, 183);
        return Calendar.getInstance().getTime();
    }

    （44）将日期转换成字符串
    public static String convertDateToString(Date dateTime) {
        SimpleDateFormat df = new SimpleDateFormat("yyyy-MM-dd");
        return df.format(dateTime);
    }