打印指定年，月的日历

输入 年 月 输出日历

package com.studyJava.calender;

import java.util.Scanner;

/**
 * 输出给定年份，月份的日历
 * 
 * @author ywf
 * 
 */
public class CalenderTest {

    // 1900年1月1日是星期一
    private final int start = 1900;
    private final int week_start = 1;

    /**
     * 输出月份对应的英文标识
     * 
     * @param n
     * @return
     */
    public String getMonthName(int n) {
        String str = "";
        switch (n) {
        case 1:
            str = "January";
            break;
        case 2:
            str = "February";
            break;
        case 3:
            str = "March";
            break;
        case 4:
            str = "Aprial";
            break;
        case 5:
            str = "May";
            break;
        case 6:
            str = "June";
            break;
        case 7:
            str = "July";
            break;
        case 8:
            str = "August";
            break;
        case 9:
            str = "September";
            break;
        case 10:
            str = "October";
            break;
        case 11:
            str = "November";
            break;
        case 12:
            str = "March";
            break;
        default:
            str = "输入月份不合理，请重新输入";
        }
        return str;
    }

    /**
     * 得到year年第month月的天数
     * 
     * @param year
     * @param month
     * @return
     */
    public int getDays(int year, int month) {
        int days = 0;
        switch (month) {
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            days = 31;
            break;
        case 4:
        case 6:
        case 9:
        case 11:
            days = 30;
            break;
        case 2:
            if (isRunyear(year)) {
                days = 29;
            } else {
                days = 28;
            }
            break;
        }
        return days;
    }

    /**
     * 判断year年是否是闰年
     * 
     * @param year
     * @return
     */
    private boolean isRunyear(int year) {
        if ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * 得到从1900年1月1日到year年month月1日的总天数
     * 
     * @param year
     * @param month
     * @return
     */
    public int getweekStart(int year, int month) {
        int daysall = 0;
        for (int i = start; i < year; i++) {
            if (isRunyear(i)) {
                daysall += 366;
            } else {
                daysall += 365;
            }
        }
        for (int i = 1; i < month; i++) {
            daysall += getDays(year, i);
        }
        return (daysall + week_start) % 7;
    }

    /**
     * 打印日历标题
     * 
     * @param year
     * @param month
     */
    public static void printCalenderTitle(String year, String month) {
        System.out.println("         " + year + " " + month + "      ");
        String str = "Sun\tMon\tTue\tWed\tThu\tFri\tSat";
        for (int i = 0; i < str.length(); i++) {
            System.out.print("_");
        }
        System.out.println();
        System.out.println("Sun\tMon\tTue\tWed\tThu\tFri\tSat");

    }

    /**
     * 打印月份体
     * 
     * @param year
     * @param month
     */
    public void printMonthBody(int year, int month) {
        int weekStart = getweekStart(year, month);// month月第一天的星期
        int days = getDays(year, month);// month月的天数
        int num = 0;
        for (int i = 0; i < weekStart; i++) {
            System.out.print("\t");
            num++;
        }
        for (int i = 0; i < days; i++) {
            if ((i + num) % 7 == 0) {
                System.out.println();
            }
            System.out.print(i + 1 + "\t");
        }
    }

    public static void main(String[] args) {
        CalenderTest test = new CalenderTest();
        Scanner input = new Scanner(System.in);
        System.out.print("Enter full year (e.g.,2001) :");
        int year = input.nextInt();
        System.out.print("\nEnter month in number between 1 and 12 :");
        int month = input.nextInt();
        String yearString = String.valueOf(year);
        String monthString = test.getMonthName(month);
        test.printCalenderTitle(yearString, monthString);
        test.printMonthBody(year, month);

    }

}