java 遍历某月的所有日期

一、工具类 方法

//获取指定月份的天数
    public static int getDaysByYearMonth(int year, int month) {

        Calendar a = Calendar.getInstance();
        a.set(Calendar.YEAR, year);
        a.set(Calendar.MONTH, month - 1);
        a.set(Calendar.DATE, 1);
        a.roll(Calendar.DATE, -1);
        int maxDate = a.get(Calendar.DATE);
        return maxDate;
    }           

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二、遍历

public void dayReport(Date month) {

        Calendar cal = Calendar.getInstance();
        cal.setTime(month);//month 为指定月份任意日期
        int year = cal.get(Calendar.YEAR);
        int m = cal.get(Calendar.MONTH);
        int dayNumOfMonth = TimeUtils.getDaysByYearMonth(year, m);
        cal.set(Calendar.DAY_OF_MONTH, 1);// 从一号开始

        for (int i = 0; i < dayNumOfMonth; i++, cal.add(Calendar.DATE, 1)) {
            Date d = cal.getTime();
            SimpleDateFormat simpleDateFormat = new SimpleDateFormat("yyyy-MM-dd");
            String df = simpleDateFormat.format(d);
       }
    }           

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