从当前日期算起，获取几天前的日期和几个月前的日期

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/**

 * 从当前日期算起，获取N天前的日期（当前日不算在内），日期格式为yyyy-MM-dd

 *

 * @param daily 天数

 * @return

 */

public static String getDateByDay(Integer daily) {

    Date date = new Date();

    int year = Integer.parseInt(new SimpleDateFormat("yyyy").format(date));

    int month = Integer.parseInt(new SimpleDateFormat("MM").format(date));

    int day = Integer.parseInt(new SimpleDateFormat("dd").format(date)) - daily;

    if (day < 1) {

        month -= 1;

        if (month == 0) {

            year -= 1;

            month = 12;

        }

        if (month == 4 || month == 6 || month == 9 || month == 11) {

            day = 30 + day;

        } else if (month == 1 || month == 3 || month == 5 || month == 7

                || month == 8 || month == 10 || month == 12) {

            day = 31 + day;

        } else if (month == 2) {

            if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {

                day = 29 + day;

            }

            else {

                day = 28 + day;

            }

        }

 

    }

    String y = year + "";

    String m = "";

    String d = "";

    if (month < 10) {

        m = "0" + month;

    } else {

        m = month + "";

    }

    if (day < 10) {

        d = "0" + day;

    } else {

        d = day + "";

    }

    return y + "-" + m + "-" + d;

}

 

/**

 * 从当前日期算起，获取N个月前的日期，日期格式为yyyy-MM-dd

 *

 * @param mon 月份

 * @return

 */

public static String getDateByMonth(Integer mon) {

    Date date = new Date();

    int year = Integer.parseInt(new SimpleDateFormat("yyyy").format(date));

    int month = Integer.parseInt(new SimpleDateFormat("MM").format(date)) - mon;

    int day = Integer.parseInt(new SimpleDateFormat("dd").format(date));

    if (month == 0) {

        year -= 1;

        month = 12;

    } else if (day > 28) {

        if (month == 2) {

            if (year % 400 == 0 || (year % 4 == 0 && year % 100 != 0)) {

                day = 29;

            } else {

                day = 28;

            }

        } else if ((month == 4 || month == 6 || month == 9 || month == 11)

                && day == 31) {

            day = 30;

        }

    }

    String y = year + "";

    String m = "";

    String d = "";

    if (month < 10) {

        m = "00" + month;

    } else {

        m = month + "";

    }

    if (day < 10) {

        d = "0" + day;

    } else {

        d = day + "";

    }

    return y + "-" + m + "-" + d;

}