Java 农历日期转换代码示例

以下是一个简单的 Java 代码示例，用于将公历日期转换为农历日期：

import java.util.Calendar;

public class LunarCalendarConverter {
    private static final int[] LUNAR_MONTH_DAYS = {
            0x0000, 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, 0x1d0b6, 0x0d250, 0x0d520, 0x0dd45, 0x0b5a0,
            0x056d0, 0x055b2, 0x049b0, 0x0a577, 0x0a4b0, 0x0aa50, 0x1b255, 0x06d20, 0x0ada0, 0x14b63
    };

    private static final int LUNAR_YEAR_START = 1900;
    private static final int LUNAR_YEAR_END = 2100;

    private static final String[] LUNAR_MONTH_NAMES = {
            '正月', '二月', '三月', '四月', '五月', '六月', '七月', '八月', '九月', '十月', '冬月', '腊月'
    };

    private static final String[] LUNAR_DAY_NAMES = {
            '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'
    };

    public static void main(String[] args) {
        int year = 2022;
        int month = 1;
        int day = 1;

        String lunarDate = convertToLunarDate(year, month, day);
        System.out.println('农历日期：' + lunarDate);
    }

    public static String convertToLunarDate(int year, int month, int day) {
        if (year < LUNAR_YEAR_START || year > LUNAR_YEAR_END) {
            throw new IllegalArgumentException('年份超出范围');
        }

        int offset = 0;
        for (int i = LUNAR_YEAR_START; i < year; i++) {
            offset += getLunarYearDays(i);
        }

        int leapMonth = getLunarLeapMonth(year);
        boolean isLeapYear = leapMonth > 0 && leapMonth <= month;

        if (isLeapYear) {
            offset += getLunarMonthDays(year, leapMonth);
        }

        for (int i = 1; i < month; i++) {
            offset += getLunarMonthDays(year, i);
        }

        offset += day - 1;

        int lunarYear = year;
        int lunarMonth = 0;
        int lunarDay = 0;

        for (int i = LUNAR_YEAR_START; i <= LUNAR_YEAR_END; i++) {
            int lunarYearDays = getLunarYearDays(i);
            if (offset >= lunarYearDays) {
                offset -= lunarYearDays;
            } else {
                lunarYear = i;
                break;
            }
        }

        for (int i = 1; i <= 12; i++) {
            int lunarMonthDays = getLunarMonthDays(lunarYear, i);
            if (offset >= lunarMonthDays) {
                offset -= lunarMonthDays;
            } else {
                lunarMonth = i;
                break;
            }
        }

        lunarDay = offset + 1;

        return lunarYear + '年' + LUNAR_MONTH_NAMES[lunarMonth - 1] + LUNAR_DAY_NAMES[lunarDay - 1];
    }

    private static int getLunarYearDays(int year) {
        int sum = 0;
        for (int i = 0x8000; i > 0x8; i >>= 1) {
            sum += (LUNAR_MONTH_DAYS[year - LUNAR_YEAR_START] & i) != 0 ? 30 : 29;
        }
        return sum + getLunarLeapMonthDays(year);
    }

    private static int getLunarLeapMonth(int year) {
        return LUNAR_MONTH_DAYS[year - LUNAR_YEAR_START] & 0xf;
    }

    private static int getLunarLeapMonthDays(int year) {
        if (getLunarLeapMonth(year) != 0) {
            return (LUNAR_MONTH_DAYS[year - LUNAR_YEAR_START] & 0x10000) != 0 ? 30 : 29;
        }
        return 0;
    }

    private static int getLunarMonthDays(int year, int month) {
        return (LUNAR_MONTH_DAYS[year - LUNAR_YEAR_START] & (0x10000 >> month)) != 0 ? 30 : 29;
    }
}

在上述代码中，我们定义了一个LunarCalendarConverter类，其中包含了转换公历日期为农历日期的静态方法convertToLunarDate。在main方法中，我们可以设置要转换的公历日期，并输出对应的农历日期。

请注意，该代码只能将1900年至2100年之间的公历日期转换为农历日期。如果需要处理其他年份的日期，可能需要进行相应的调整。