CalendarUtils.java

import java.util.*;

public class CalendarUtils {

	private static final String[] weekTitle = {"一", "二", "三", "四", "五", "六", "日"};
	private static final String[] monthTitle = {"一月", "二月", "三月", "四月", "五月", "六月", "七月", "八月", "九月", "十月", "十一月", "十二月"};
	private static final int[] monthSize = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

	private CalendarUtils() {
		// No Construct function
	}

	/**
	 * 主方法
	 */
	public static void getCalendar(final int year) {
		for (int month = 0; month < monthTitle.length; month++) {
			printMonthtitle(monthTitle[month]);
			printMonthBody(year, month + 1);
		}
	}

	/**
	 * 是不是闰年
	 */
	private static boolean isLeapYear(final int year) {
		return year % 100 == 0 ? year % 400 == 0 : year % 4 == 0;
	}

	/**
	 * 循环打印月标题
	 */
	private static void printMonthtitle(final String monthTitle) {
		System.out.println("                     " + monthTitle);
	}

	/**
	 * 循环打印月日历
	 */
	private static void printMonthBody(final int year, final int month) {
		printWeekTitle();
		for (int i = 0; i < (getMonthSize(year, month) + getStartOffset(year, month)); i++) {
			if (i < getStartOffset(year, month)) {
				System.out.print("\t");
			} else {
				System.out.print(i + 1 - getStartOffset(year, month));
				if ((i + 1) % 7 == 0) {
					System.out.print("\n");
				} else {
					System.out.print("\t");
				}
			}
		}
		System.out.println("\n");
	}

	/**
	 * 循环打印周标题
	 */
	private static void printWeekTitle() {
		for (int i = 0; i < weekTitle.length; i++) {
			System.out.print(weekTitle[i] + (i == 6 ? "\n": "\t"));
		}
	}

	/**
	 * 获取这个月的天数
	 */
	private static int getMonthSize(final int year, final int month) {
		return (isLeapYear(year) && month == 2) ? 29 : monthSize[month - 1];
	}

	/**
	 * 获取这个月第一天的开始周 蔡勒(zeller)公式
	 */
	private static int getStartOffset(int year, int month) {
		int week = 0;
		if (month < 3) {
			month += 12;
			year--;
		}
		int century = year / 100;
		year = year % 100;
		week = year + year / 4 + century / 4 - 2 * century + (26 * (month + 1))/ 10;
		week = week % 7;
		return week == 0 ? 6 : week - 1;
	}
}