阳历转农历

转自：http://www.blogjava.net/soddabao/archive/2007/01/04/91729.html

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

public class Lunar {
 private int year;
 private int month;
 private int day;
 private boolean leap;
 final static String chineseNumber[] = { "一", "二", "三", "四", "五", "六", "七",
   "八", "九", "十", "十一", "十二" };
 static SimpleDateFormat chineseDateFormat = new SimpleDateFormat(
   "yyyy年MM月dd日");
 final static long[] lunarInfo = 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 };

 // ====== 传回农历 y年的总天数
 final private static int yearDays(int y) {
  int i, sum = 348;
  for (i = 0x8000; i > 0x8; i >>= 1) {
   if ((lunarInfo[y - 1900] & i) != 0)
    sum += 1;
  }
  return (sum + leapDays(y));
 }

 // ====== 传回农历 y年闰月的天数
 final private static int leapDays(int y) {
  if (leapMonth(y) != 0) {
   if ((lunarInfo[y - 1900] & 0x10000) != 0)
    return 30;
   else
    return 29;
  } else
   return 0;
 }

 // ====== 传回农历 y年闰哪个月 1-12 , 没闰传回 0
 final private static int leapMonth(int y) {
  return (int) (lunarInfo[y - 1900] & 0xf);
 }

 // ====== 传回农历 y年m月的总天数
 final private static int monthDays(int y, int m) {
  if ((lunarInfo[y - 1900] & (0x10000 >> m)) == 0)
   return 29;
  else
   return 30;
 }

 // ====== 传回农历 y年的生肖
 final public String animalsYear() {
  final String[] Animals = new String[] { "鼠", "牛", "虎", "兔", "龙", "蛇",
    "马", "羊", "猴", "鸡", "狗", "猪" };
  return Animals[(year - 4) % 12];
 }

 // ====== 传入 月日的offset 传回干支, 0=甲子
 final private static String cyclicalm(int num) {
  final String[] Gan = new String[] { "甲", "乙", "丙", "丁", "戊", "己", "庚",
    "辛", "壬", "癸" };
  final String[] Zhi = new String[] { "子", "丑", "寅", "卯", "辰", "巳", "午",
    "未", "申", "酉", "戌", "亥" };
  return (Gan[num % 10] + Zhi[num % 12]);
 }

 // ====== 传入 offset 传回干支, 0=甲子
 final public String cyclical() {
  int num = year - 1900 + 36;
  return (cyclicalm(num));
 }

 /** */
 /**
  * 传出y年m月d日对应的农历. yearCyl3:农历年与1864的相差数 ? monCyl4:从1900年1月31日以来,闰月数
  * dayCyl5:与1900年1月31日相差的天数,再加40 ?
  *
  * @param cal
  * @return
  */
 public Lunar(Calendar cal) {
  @SuppressWarnings("unused")
  int yearCyl, monCyl, dayCyl;
  int leapMonth = 0;
  Date baseDate = null;
  try {
   baseDate = chineseDateFormat.parse("1900年1月31日");
  } catch (ParseException e) {
   e.printStackTrace(); // To change body of catch statement use
         // Options | File Templates.
  }

  // 求出和1900年1月31日相差的天数
  int offset = (int) ((cal.getTime().getTime() - baseDate.getTime()) / 86400000L);
  dayCyl = offset + 40;
  monCyl = 14;

  // 用offset减去每农历年的天数
  // 计算当天是农历第几天
  // i最终结果是农历的年份
  // offset是当年的第几天
  int iYear, daysOfYear = 0;
  for (iYear = 1900; iYear < 2050 && offset > 0; iYear++) {
   daysOfYear = yearDays(iYear);
   offset -= daysOfYear;
   monCyl += 12;
  }
  if (offset < 0) {
   offset += daysOfYear;
   iYear--;
   monCyl -= 12;
  }
  // 农历年份
  year = iYear;

  yearCyl = iYear - 1864;
  leapMonth = leapMonth(iYear); // 闰哪个月,1-12
  leap = false;

  // 用当年的天数offset,逐个减去每月（农历）的天数，求出当天是本月的第几天
  int iMonth, daysOfMonth = 0;
  for (iMonth = 1; iMonth < 13 && offset > 0; iMonth++) {
   // 闰月
   if (leapMonth > 0 && iMonth == (leapMonth + 1) && !leap) {
    --iMonth;
    leap = true;
    daysOfMonth = leapDays(year);
   } else
    daysOfMonth = monthDays(year, iMonth);

   offset -= daysOfMonth;
   // 解除闰月
   if (leap && iMonth == (leapMonth + 1))
    leap = false;
   if (!leap)
    monCyl++;
  }
  // offset为0时，并且刚才计算的月份是闰月，要校正
  if (offset == 0 && leapMonth > 0 && iMonth == leapMonth + 1) {
   if (leap) {
    leap = false;
   } else {
    leap = true;
    --iMonth;
    --monCyl;
   }
  }
  // offset小于0时，也要校正
  if (offset < 0) {
   offset += daysOfMonth;
   --iMonth;
   --monCyl;
  }
  month = iMonth;
  day = offset + 1;
 }

 public static String getChinaDayString(int day) {
  String chineseTen[] = { "初", "十", "廿", "卅" };
  int n = day % 10 == 0 ? 9 : day % 10 - 1;
  if (day > 30)
   return "";
  if (day == 10)
   return "初十";
  else
   return chineseTen[day / 10] + chineseNumber[n];
 }

 public String toString() {
  return year + "年" + (leap ? "闰" : "") + chineseNumber[month - 1] + "月"
    + getChinaDayString(day);
 }

 public static void main(String[] args) throws ParseException {
  Calendar today = Calendar.getInstance();
  today.setTime(chineseDateFormat.parse("2010年3月31日"));
  Lunar lunar = new Lunar(today);

  System.out.println("北京时间：" + chineseDateFormat.format(today.getTime())
    + "　农历" + lunar);
 }
}