Java中的Date详解

1、java.util.Date

java.sql.Date,java.sql.Time和java.sql.Timestamp三个都是java.util.Date的子类（包装类）。

https://blog.csdn.net/tjgykhulj/article/details/68953191

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   
       

    public static void main(String[] args) {   
        TimeTest tt = new TimeTest();   
        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2008-12-1~2008-9.29:"+TimeTest.getTwoDay("2008-12-1","2008-9-29"));   
    }   
       
       
    /**  
        * 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  
        *   
        * @param sdate  
        * @return  
        */  
    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   
        *   
        * @param strDate  
        * @return  
        */  
    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)+"-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;   
           
    }   
       
    /**  
     * 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);   
  }   
}  
l另外的一种方法
 
/**  
     * 获取系统时间  
     * @return  
     */  
    public String getDate(){   
           
         Calendar ca = Calendar.getInstance();   
          int year = ca.get(Calendar.YEAR);//获取年份   
          int month=ca.get(Calendar.MONTH);//获取月份    
          int day=ca.get(Calendar.DATE);//获取日   
          int minute=ca.get(Calendar.MINUTE);//分    
          int hour=ca.get(Calendar.HOUR);//小时    
          int second=ca.get(Calendar.SECOND);//秒   
             
          String date = year + "年" + (month + 1 )+ "月" + day + "日"+ hour + "时" + minute + "分" + second + "秒";   
  
  
          return date;   
           
    }