DateUtil-常用关于date的工具类备份

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public class DateUtil {
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    /**
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     * 根据开始与结束日期获取相减得到的天数
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     * @param beginDateStr
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     * @param endDateStr
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     * @return
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     */
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    public static long getDaySub(String beginDateStr,String endDateStr){
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        long day=0;
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        java.text.SimpleDateFormat format = new java.text.SimpleDateFormat("yyyy-MM-dd");
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        java.util.Date beginDate;
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        java.util.Date endDate;
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        try{
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            beginDate = format.parse(beginDateStr);
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            endDate= format.parse(endDateStr);
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            day=(endDate.getTime()-beginDate.getTime())/(24*60*60*1000);
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            //System.out.println("相隔的天数="+day);
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        } catch (ParseException e){
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            // TODO 自动生成 catch 块
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            e.printStackTrace();
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        }
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        return day;
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    }
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    /**
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     * 日期 Date 转 String
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     * @param date
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     * @param type
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     * @return
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     */
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    public static String DateToString(Date date,String type){
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        SimpleDateFormat dateFormat = new SimpleDateFormat(type);
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        return dateFormat.format(date);
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    }
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    /**
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     * 时间字符串转为新的type样式的时间字符串
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     * @param dateString
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     * @param type
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     * @return
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     */
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    public static String StringToNewStringOfDate(String dateString,String type){
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        SimpleDateFormat sdf = new SimpleDateFormat(type);
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        Date date = null;
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        try {
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            date = sdf.parse(dateString);
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        } catch (ParseException e) {
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            e.printStackTrace();
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        }
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       return sdf.format(date);
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    }
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    /**
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     * 时间 String 转 Date
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     * @param dateString
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     * @param type
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     * @return
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     */
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    public static Date StringToDate(String dateString,String type){
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        SimpleDateFormat sdf = new SimpleDateFormat(type);
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        Date date = null;
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        try {
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             date = sdf.parse(dateString);
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        } catch (ParseException e) {
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            e.printStackTrace();
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        }
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        return date;
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    }
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    /**
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     * 时间 String 转 Calendar
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     * @param dateString
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     * @param type
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     * @return
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     */
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    public static Calendar StringtoCalendar(String dateString,String type){
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        SimpleDateFormat sdf= new SimpleDateFormat(type);
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        Date date = null;
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        try {
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            date = sdf.parse(dateString);
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        } catch (ParseException e) {
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            e.printStackTrace();
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        }
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        Calendar calendar = Calendar.getInstance();
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        calendar.setTime(date);
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        return calendar;
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    }
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    /**
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     * 在指定日期上加一天
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     * @param date
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     * @return
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     */
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    public static Date addDateOneDay(Date date) {
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        if (null == date) {
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            return date;
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        }
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        Calendar c = Calendar.getInstance();
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        c.setTime(date);   //设置当前日期
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        c.add(Calendar.DATE, 1); //日期加1天
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//     c.add(Calendar.DATE, -1); //日期减1天
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        date = c.getTime();
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        return date;
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    }
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    /**
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     * // 获取当日期的前后日期 i为正数 向后推迟i天，负数时向前提前i天
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     * @param i
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     * @return
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     */
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    public static Date getNumdate(int i) {
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        Calendar cd = Calendar.getInstance();
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        cd.add(Calendar.DATE, i);
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        return cd.getTime();
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    }
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    /**
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     * 获取某月的第一天
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     *  0当月
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     *  -1 前一个月
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     *  1 后一个月
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     * @param i
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     * @return
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     */
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    public static Date getNumMonth(int i){
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        Calendar   cal_1=Calendar.getInstance();//获取当前日期
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        cal_1.add(Calendar.MONTH, i);
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        cal_1.set(Calendar.DAY_OF_MONTH,1);
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        return cal_1.getTime();
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    }
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    /**
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     * 获取本周日的日期
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     * @return
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     */
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    public static Date getSundayOfThisWeek() {
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        Calendar c = Calendar.getInstance();
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        int day_of_week = c.get(Calendar.DAY_OF_WEEK) - 1;
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        if (day_of_week == 0)
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            day_of_week = 7;
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        c.add(Calendar.DATE, -day_of_week + 7);
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        return c.getTime();
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    }
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    /**
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     * 获取本周一的日期
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     * @return
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     */
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    public static Date getMondayOfThisWeek() {
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        Calendar c = Calendar.getInstance();
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        int day_of_week = c.get(Calendar.DAY_OF_WEEK) - 1;
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        if (day_of_week == 0)
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            day_of_week = 7;
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        c.add(Calendar.DATE, -day_of_week + 1);
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        return c.getTime();
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    }
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}