中国年历算法和程式

本文摘自“和荣笔记 - 中国农历二百年算法及年历”

中国公历算法

中国公历算法不是太难，关键是星期值的确定。这里给出了简单算法：

public static int dayOfWeek(int y, int m, int d) 
{ int w = 1; 
// 公历一年一月一日是星期一，所以起始值为星期日 y = (y-1)%400 + 1; 
// 公历星期值分部 400 年循环一次 int ly = (y-1)/4; 
// 闰年次数 ly = ly - (y-1)/100; ly = ly + (y-1)/400; int ry = y - 1 - ly; 
// 常年次数 w = w + ry; 
// 常年星期值增一 w = w + 2*ly; 
// 闰年星期值增二 w = w + dayOfYear(y,m,d); w = (w-1)%7 + 1; return w; }

中国农历算法

根公历相比，中国农历的算法相当复杂。我在网上找的算法之中，eleworld.com 的算法是最好的一个。这个算法使用了大量的数据来确定农历月份和节气的分部，它仅实用于公历 1901 年到 2100 年之间的 200 年。

中国农历计算程式

跟据 eleworld.com 提供的算法，我写了下面这个程式： [HTML]

/**
 * ChineseCalendarGB.java
 * Copyright (c) 1997-2002 by Dr. Herong Yang. http://www.herongyang.com/
 * 中国农历算法 - 实用于公历 1901 年至 2100 年之间的 200 年 
 */
import java.text.*;
import java.util.*;
class ChineseCalendarGB {
   private int gregorianYear;
   private int gregorianMonth;
   private int gregorianDate;
   private boolean isGregorianLeap;
   private int dayOfYear;
   private int dayOfWeek; // 周日一星期的第一天
   private int chineseYear;
   private int chineseMonth; // 负数表示闰月
   private int chineseDate;
   private int sectionalTerm;
   private int principleTerm;
   private static char[] daysInGregorianMonth = 
      {31,28,31,30,31,30,31,31,30,31,30,31};
   private static String[] stemNames =
      {"甲","乙","丙","丁","戊","己","庚","辛","壬","癸"};
   private static String[] branchNames =
      {"子","丑","寅","卯","辰","巳","午","未","申","酉","戌","亥"};
   private static String[] animalNames =
      {"鼠","牛","虎","兔","龙","蛇","马","羊","猴","鸡","狗","猪"};
   public static void main(String[] arg) {
      ChineseCalendarGB c = new ChineseCalendarGB();
      String cmd = "day";
      int y = 1901;
      int m = 1;
      int d = 1;
      if (arg.length>0) cmd = arg[0];
      if (arg.length>1) y = Integer.parseInt(arg[1]);
      if (arg.length>2) m = Integer.parseInt(arg[2]);
      if (arg.length>3) d = Integer.parseInt(arg[3]);
      c.setGregorian(y,m,d);
      c.computeChineseFields();
      c.computeSolarTerms();
      if (cmd.equalsIgnoreCase("year")) {
         String[] t = c.getYearTable();
         for (int i=0; i      } else if (cmd.equalsIgnoreCase("month")) {
         String[] t = c.getMonthTable();
         for (int i=0; i      } else {
         System.out.println(c.toString());
      }
   }
   public ChineseCalendarGB() {
      setGregorian(1901,1,1);
   }
   public void setGregorian(int y, int m, int d) {
      gregorianYear = y;
      gregorianMonth = m;
      gregorianDate = d;
      isGregorianLeap = isGregorianLeapYear(y);
      dayOfYear = dayOfYear(y,m,d);
      dayOfWeek = dayOfWeek(y,m,d);
      chineseYear = 0;
      chineseMonth = 0;
      chineseDate = 0;
      sectionalTerm = 0;
      principleTerm = 0;
   }
   public static boolean isGregorianLeapYear(int year) {
      boolean isLeap = false;
      if (year%4==0) isLeap = true;
      if (year%100==0) isLeap = false;
      if (year%400==0) isLeap = true;
      return isLeap;
   }
   public static int daysInGregorianMonth(int y, int m) {
      int d = daysInGregorianMonth[m-1];
      if (m==2 && isGregorianLeapYear(y)) d++; // 公历闰年二月多一天
      return d;
   }
   public static int dayOfYear(int y, int m, int d) {
      int c = 0;
      for (int i=1; i         c = c + daysInGregorianMonth(y,i);
      }
      c = c + d;
      return c;      
   }
   public static int dayOfWeek(int y, int m, int d) {
      int w = 1; // 公历一年一月一日是星期一，所以起始值为星期日
      y = (y-1)%400 + 1; // 公历星期值分部 400 年循环一次
      int ly = (y-1)/4; // 闰年次数
      ly = ly - (y-1)/100;
      ly = ly + (y-1)/400;
      int ry = y - 1 - ly; // 常年次数
      w = w + ry; // 常年星期值增一
      w = w + 2*ly; // 闰年星期值增二
      w = w + dayOfYear(y,m,d); 
      w = (w-1)%7 + 1;
      return w;
   }
   private static char[] chineseMonths = { 
   // 农历月份大小压缩表，两个字节表示一年。两个字节共十六个二进制位数， 
   // 前四个位数表示闰月月份，后十二个位数表示十二个农历月份的大小。
   0x00,0x04,0xad,0x08,0x5a,0x01,0xd5,0x54,0xb4,0x09,0x64,0x05,0x59,0x45,
   0x95,0x0a,0xa6,0x04,0x55,0x24,0xad,0x08,0x5a,0x62,0xda,0x04,0xb4,0x05,
   0xb4,0x55,0x52,0x0d,0x94,0x0a,0x4a,0x2a,0x56,0x02,0x6d,0x71,0x6d,0x01,
   0xda,0x02,0xd2,0x52,0xa9,0x05,0x49,0x0d,0x2a,0x45,0x2b,0x09,0x56,0x01,
   0xb5,0x20,0x6d,0x01,0x59,0x69,0xd4,0x0a,0xa8,0x05,0xa9,0x56,0xa5,0x04,
   0x2b,0x09,0x9e,0x38,0xb6,0x08,0xec,0x74,0x6c,0x05,0xd4,0x0a,0xe4,0x6a,
   0x52,0x05,0x95,0x0a,0x5a,0x42,0x5b,0x04,0xb6,0x04,0xb4,0x22,0x6a,0x05,
   0x52,0x75,0xc9,0x0a,0x52,0x05,0x35,0x55,0x4d,0x0a,0x5a,0x02,0x5d,0x31,
   0xb5,0x02,0x6a,0x8a,0x68,0x05,0xa9,0x0a,0x8a,0x6a,0x2a,0x05,0x2d,0x09,
   0xaa,0x48,0x5a,0x01,0xb5,0x09,0xb0,0x39,0x64,0x05,0x25,0x75,0x95,0x0a,
   0x96,0x04,0x4d,0x54,0xad,0x04,0xda,0x04,0xd4,0x44,0xb4,0x05,0x54,0x85,
   0x52,0x0d,0x92,0x0a,0x56,0x6a,0x56,0x02,0x6d,0x02,0x6a,0x41,0xda,0x02,
   0xb2,0xa1,0xa9,0x05,0x49,0x0d,0x0a,0x6d,0x2a,0x09,0x56,0x01,0xad,0x50,
   0x6d,0x01,0xd9,0x02,0xd1,0x3a,0xa8,0x05,0x29,0x85,0xa5,0x0c,0x2a,0x09,
   0x96,0x54,0xb6,0x08,0x6c,0x09,0x64,0x45,0xd4,0x0a,0xa4,0x05,0x51,0x25,
   0x95,0x0a,0x2a,0x72,0x5b,0x04,0xb6,0x04,0xac,0x52,0x6a,0x05,0xd2,0x0a,
   0xa2,0x4a,0x4a,0x05,0x55,0x94,0x2d,0x0a,0x5a,0x02,0x75,0x61,0xb5,0x02,
   0x6a,0x03,0x61,0x45,0xa9,0x0a,0x4a,0x05,0x25,0x25,0x2d,0x09,0x9a,0x68,
   0xda,0x08,0xb4,0x09,0xa8,0x59,0x54,0x03,0xa5,0x0a,0x91,0x3a,0x96,0x04,
   0xad,0xb0,0xad,0x04,0xda,0x04,0xf4,0x62,0xb4,0x05,0x54,0x0b,0x44,0x5d,
   0x52,0x0a,0x95,0x04,0x55,0x22,0x6d,0x02,0x5a,0x71,0xda,0x02,0xaa,0x05,
   0xb2,0x55,0x49,0x0b,0x4a,0x0a,0x2d,0x39,0x36,0x01,0x6d,0x80,0x6d,0x01,
   0xd9,0x02,0xe9,0x6a,0xa8,0x05,0x29,0x0b,0x9a,0x4c,0xaa,0x08,0xb6,0x08,
   0xb4,0x38,0x6c,0x09,0x54,0x75,0xd4,0x0a,0xa4,0x05,0x45,0x55,0x95,0x0a,
   0x9a,0x04,0x55,0x44,0xb5,0x04,0x6a,0x82,0x6a,0x05,0xd2,0x0a,0x92,0x6a,
   0x4a,0x05,0x55,0x0a,0x2a,0x4a,0x5a,0x02,0xb5,0x02,0xb2,0x31,0x69,0x03,
   0x31,0x73,0xa9,0x0a,0x4a,0x05,0x2d,0x55,0x2d,0x09,0x5a,0x01,0xd5,0x48,
   0xb4,0x09,0x68,0x89,0x54,0x0b,0xa4,0x0a,0xa5,0x6a,0x95,0x04,0xad,0x08,
   0x6a,0x44,0xda,0x04,0x74,0x05,0xb0,0x25,0x54,0x03
   };
   // 初始日，公历农历对应日期：
   // 公历 1901 年 1 月 1 日，对应农历 4598 年 11 月 11 日
   private static int baseYear = 1901;
   private static int baseMonth = 1;
   private static int baseDate = 1;
   private static int baseIndex = 0;
   private static int baseChineseYear = 4598-1;
   private static int baseChineseMonth = 11;
   private static int baseChineseDate = 11;
   public int computeChineseFields() {
      if (gregorianYear<1901 || gregorianYear>2100) return 1;
      int startYear = baseYear;
      int startMonth = baseMonth;
      int startDate = baseDate;      
      chineseYear = baseChineseYear; 
      chineseMonth = baseChineseMonth;
      chineseDate = baseChineseDate;
      // 第二个对应日，用以提高计算效率
      // 公历 2000 年 1 月 1 日，对应农历 4697 年 11 月 25 日
      if (gregorianYear >= 2000) {
         startYear = baseYear + 99;
         startMonth = 1;
         startDate = 1;
         chineseYear = baseChineseYear + 99;
         chineseMonth = 11;
         chineseDate = 25;
      }
      int daysDiff = 0;
      for (int i=startYear; i         daysDiff += 365;
         if (isGregorianLeapYear(i)) daysDiff += 1; // leap year
      }
      for (int i=startMonth; i         daysDiff += daysInGregorianMonth(gregorianYear,i);
      }
      daysDiff += gregorianDate - startDate;
      
      chineseDate += daysDiff;
      int lastDate = daysInChineseMonth(chineseYear, chineseMonth);
      int nextMonth = nextChineseMonth(chineseYear, chineseMonth);
      while (chineseDate>lastDate) {
         if (Math.abs(nextMonth)         chineseMonth = nextMonth;
         chineseDate -= lastDate;
         lastDate = daysInChineseMonth(chineseYear, chineseMonth);
         nextMonth = nextChineseMonth(chineseYear, chineseMonth);
      }
      return 0;
   }
   private static int[] bigLeapMonthYears = {
      // 大闰月的闰年年份
        6, 14, 19, 25, 33, 36, 38, 41, 44, 52, 
       55, 79,117,136,147,150,155,158,185,193
      };
   public static int daysInChineseMonth(int y, int m) {
      // 注意：闰月 m < 0
      int index = y - baseChineseYear + baseIndex;
      int v = 0;
      int l = 0;
      int d = 30;
      if (1<=m && m<=8) {
         v = chineseMonths[2*index];
         l = m - 1;
         if ( ((v>>l)&0x01)==1 ) d = 29;
      } else if (9<=m && m<=12) {
         v = chineseMonths[2*index+1];
         l = m - 9;
         if ( ((v>>l)&0x01)==1 ) d = 29;
      } else {
         v = chineseMonths[2*index+1];
         v = (v>>4)&0x0F;
         if (v!=Math.abs(m)) {
            d = 0;
         } else {
            d = 29; 
            for (int i=0; i               if (bigLeapMonthYears[i]==index) {
                  d = 30;
                  break;
               }
            }
         }
      }
      return d;
   }
   public static int nextChineseMonth(int y, int m) {
      int n = Math.abs(m) + 1;
      if (m>0) {
  
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