android 公历转农历

Android 提供了 `Calendar` 类来进行日期转换。但是，要将公历转换为农历需要借助第三方库或自己实现算法。

以下是一个自己实现农历转换算法的示例代码：

public class LunarUtil {

    private static final String[] CHINESE_MONTHS = {
            "正", "二", "三", "四", "五", "六",
            "七", "八", "九", "十", "冬", "腊"
    };

    private static final String[] CHINESE_DAYS = {
            "初一", "初二", "初三", "初四", "初五", "初六", "初七", "初八", "初九", "初十",
            "十一", "十二", "十三", "十四", "十五", "十六", "十七", "十八", "十九", "二十",
            "廿一", "廿二", "廿三", "廿四", "廿五", "廿六", "廿七", "廿八", "廿九", "三十"
    };

    private static final long[] LUNAR_INFO = new long[]{
            0x04bd8, 0x04ae0, 0x0a570, 0x054d5, 0x0d260, 0x0d950, 0x16554, 0x056a0,
            0x09ad0, 0x055d2, 0x04ae0, 0x0a5b6, 0x0a4d0, 0x0d250, 0x1d255, 0x0b540,
            0x0d6a0, 0x0ada2, 0x095b0, 0x14977, 0x04970, 0x0a4b0, 0x0b4b5, 0x06a50,
            0x06d40, 0x1ab54, 0x02b60, 0x09570, 0x052f2, 0x04970, 0x06566, 0x0d4a0,
            0x0ea50, 0x06e95, 0x05ad0, 0x02b60, 0x186e3, 0x092e0, 0x1c8d7, 0x0c950,
            0x0d4a0, 0x1d8a6, 0x0b550, 0x056a0, 0x1a5b4, 0x025d0, 0x092d0, 0x0d2b2,
            0x0a950, 0x0b557, 0x06ca0, 0x0b550, 0x15355, 0x04da0, 0x0a5d0, 0x14573,
            0x052d0, 0x0a9a8, 0x0e950, 0x06aa0, 0x0aea6, 0x0ab50, 0x04b60, 0x0aae4,
            0x0a570, 0x05260, 0x0f263, 0x0d950, 0x05b57, 0x056a0, 0x096d0, 0x04dd5,
            0x04ad0, 0x0a4d0, 0x0d4d4, 0x0d250, 0x0d558, 0x0b540, 0x0b5a0, 0x195a6,
            0x095b0, 0x049b0, 0x0a974, 0x0a4b0, 0x0b27a, 0x06a50, 0x06d40, 0x0af46,
            0x0ab60, 0x09570, 0x04af5, 0x04970, 0x064b0, 0x074a3, 0x0ea50, 0x06b58,
            0x055c0, 0x0ab60, 0x096d5, 0x092e0, 0x0c960, 0x0d954, 0x0d4a0, 0x0da50,
            0x07552, 0x056a0, 0x0abb7, 0x025d0, 0x092d0, 0x0cab5, 0x0a950, 0x0b4a0,
            0x0baa4, 0x0ad50, 0x055d9, 0x04ba0, 0x0a5b0, 0x15176, 0x052b0, 0x0a930,
            0x07954, 0x06aa0, 0x0ad50, 0x05b52, 0x04b60, 0x0a6e6, 0x0a4e0, 0x0d260,
            0x0ea65, 0x0d530, 0x05aa0, 0x076a3, 0x096d0, 0x04bd7, 0x04ad0, 0x0a4d0,
            0x1d0b6, 0x0d250, 0x0d520, 0x0dd45, 0x0b5a0, 0x056d0, 0x055b2, 0x049b0,
            0x0a577, 0x0a4b0, 0x0aa50, 0x1b255, 0x06d20, 0x0ada0
    };

    private static final int BASE_YEAR = 1900;

    private static final int BASE_MONTH = 1;

    private static final int BASE_DAY = 31;

    /**
     * 将公历日期转换成农历日期
     *
     * @param year  公历年份
     * @param month 公历月份，从1开始
     * @param day   公历日
     * @return 农历日期，格式为"农历x月x日"
     */
    public static String solarToLunar(int year, int month, int day) {
        int offset = 0;
        int leapMonth = 0;
        int iYear, iMonth, iDay;

        try {
            Date baseDate = new SimpleDateFormat("yyyy-MM-dd").parse("1900-01-31");
            Date nowDate = new SimpleDateFormat("yyyy-MM-dd").parse(year + "-" + month + "-" + day);

            long offsetTime = (nowDate.getTime() - baseDate.getTime()) / 86400000;
            for (iYear = BASE_YEAR; iYear < 2100 && offsetTime > 0; iYear++) {
                offset = getYearDays(iYear);
                offsetTime -= offset;
            }

            if (offsetTime < 0) {
                offsetTime += offset;
                iYear--;
            }

            leapMonth = getLeapMonth(iYear);
            boolean isLeap = false;

            for (iMonth = BASE_MONTH; iMonth < 13 && offsetTime > 0; iMonth++) {
                if (leapMonth > 0 && iMonth == leapMonth + 1 && !isLeap) {
                    iMonth--;
                    isLeap = true;
                    offset = getLeapMonthDays(iYear);
                } else {
                    offset = getMonthDays(iYear, iMonth);
                }

                if (isLeap && iMonth == leapMonth + 1) {
                    isLeap = false;
                }

                offsetTime -= offset;
            }

            if (offsetTime == 0 && leapMonth > 0 && iMonth == leapMonth + 1) {
                if (isLeap) {
                    isLeap = false;
                } else {
                    isLeap = true;
                    iMonth--;
                }
            }

            if (offsetTime < 0) {
                offsetTime += offset;
                iMonth--;
            }

            iDay = (int) (offsetTime + 1);
        } catch (ParseException e) {
            e.printStackTrace();
            return "";
        }

        return CHINESE_MONTHS[iMonth - 1] + "月" + getChinaDayString(iDay, isLeap);
    }

    private static int getYearDays(int year) {
        int sum = 348;
        for (int i = 0x8000; i > 0x8; i >>= 1) {
            if ((LUNAR_INFO[year - BASE_YEAR] & i) != 0) {
                sum += 1;
            }
        }
        return sum + getLeapMonthDays(year);
    }

    private static int getLeapMonth(int year) {
        return (int) (LUNAR_INFO[year - BASE_YEAR] & 0xf);
    }

    private static int getLeapMonthDays(int year) {
        if (getLeapMonth(year) != 0) {
            if ((LUNAR_INFO[year - BASE_YEAR] & 0x10000) != 0) {
                return 30;
            } else {
                return 29;
            }
        } else {
            return 0;
        }
    }

    private static int getMonthDays(int year, int month) {
        if ((LUNAR_INFO[year - BASE_YEAR] & (0x10000 >> month)) == 0) {
            return 29;
        } else {
            return 30;
        }
    }

    private static String getChinaDayString(int day, boolean isLeap) {
        if (day == 1 && isLeap) {
            return "闰" + CHINESE_DAYS[day - 1];
        }
        return CHINESE_DAYS[day - 1];
    }
}

使用方法：

String lunar = LunarUtil.solarToLunar(2022, 1, 1);
System.out.println(lunar); // 农历正月初一