【java基础】Calendar与LocalDateTime

Calendar与LocalDateTime

1.Calendar

SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Calendar c = Calendar.getInstance();
 
//过去七天
c.setTime(new Date());
c.add(Calendar.DATE, -7);
Date d = c.getTime();
String day = format.format(d);
System.out.println("过去七天："+day);
 
//过去一月
c.setTime(new Date());
c.add(Calendar.MONTH, -1);
Date m = c.getTime();
String mon = format.format(m);
System.out.println("过去一个月："+mon);
 
//过去三个月
c.setTime(new Date());
c.add(Calendar.MONTH, -3);
Date m3 = c.getTime();
String mon3 = format.format(m3);
System.out.println("过去三个月："+mon3);
 
//过去一年
c.setTime(new Date());
c.add(Calendar.YEAR, -1);
Date y = c.getTime();
String year = format.format(y);
System.out.println("过去一年："+year);

工具类

    package com.lzq.time;


/**
 * ChineseCalendarGB.java Copyright (c) 1997-2002 by Dr. Herong Yang 中国农历算法 -
 * 实用于公历 1901 年至 2100 年之间的 200 年
 */
public class CalendarUtil {
   
	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 final String[] daysOfMonth = {
    "1", "2", "3", "4", "5", "6",
			"7", "8", "9", "10", "11", "12", "13", "14", "15", "16", "17",
			"18", "19", "20", "21", "22", "23", "24", "25", "26", "27", "28",
			"29", "30", "31" };

	private String monthOfAlmanac[] = {
   "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 String daysOfAlmanac[] = {
    "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" }; // 农历的天数

	public CalendarUtil() {
   
		setGregorian(1901, 1, 1);
	}

	/**
	 * 得到对应天的农历 要判断闰月 月初 月末	 * 
	 * @param y
	 * @param m
	 * @param d
	 * @return String

	 */
	public String getChineseDay(int y, int m, int d) {
   

		CalendarUtil c = new CalendarUtil();

		c.setGregorian(y, m, d);
		c.computeChineseFields();
		c.computeSolarTerms();

		int cd = c.getChineseDate();

		return daysOfAlmanac[cd - 1];
	}

	/**

     *  得到对应天的农历
     *  要判断闰月 月初 月末
     * @param y
     * @param m
     * @param d
     * @return

     */
	public String getChineseMonth(int y, int m, int d) {
   
		setGregorian(y,m,d);
		computeChineseFields();
		computeSolarTerms();
		
		int cd = getChineseMonth();
		if(cd < 1 || cd > 29)
			cd = 1;
		return monthOfAlmanac[cd -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;
	}

	// 判断是否是闰年
	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;
	}

	// 返回一个月有几天
	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;
	}

	// 计算当前天在本年中是第几天
	public static int dayOfYear(int y, int m, int d) {
   
		int c = 0;
		for (int i = 1; i < m; i++) {
   
			c = c + daysInGregorianMonth(y, i);
		}
		c = c + d;
		return c;
	}

	// 当前天是本周的第几天 ， 从星期天开始算
	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;
	}

	// 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。
	private static char[] chineseMonths = {
    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()