万年历代码

public class Demo03 {
//获取每年首日周几
public static int kalendar(int year, int month) {
Calendar calendar = Calendar.getInstance();
calendar.set(year,0,1,0,0,0);
Date date = calendar.getTime();
long atYear = date.getTime();
int weekday =((year - 1970)*365+leapyear(year,month) + 4) % 7;
return weekday;

}
//获取闰年年数
public static int leapyear(int year, int month) {
	int count = 0 ;
	for(int i = 1970; i < year; i++ ) {
		if ( (i % 4 == 0 && i % 100 !=0) || i % 400 == 0) {
			count += 1;
		}
	}
		
	return count;
}
//打印每月日期
public static void show(int year, int month) {
	int m = kalendar(year,month);
	if ( (year % 4 == 0 && year % 100 !=0) || year % 400 == 0) {
		switch(month) {
			case 1:
				for (int j = 0;j < m ; j++) {
					System.out.print(" "+"\t");
				}
				for (int i = 1; i <= 31; i++) {
					if((m-1+i) % 7 == 0 ) {
						System.out.println(i);
					}else {
						System.out.print(i+"\t");
					}
				}
				
				break;
			case 2:
				for (int j = 0;j <(31+m-1)%7; j++) {
					System.out.print(" "+"\t");
				}
				for (int i = 1; i <= 29; i++) {
					if(((31+m-1+i)) % 7 == 0 ) {
						System.out.println(i);
					}else {
						
						System.out.print(i+"\t");
					}
				}
				break;
			case 3:
				for (int j = 0;j <(60+m-1)%7; j++) {
					System.out.print(" "+"\t");
				}
				for (int i = 1; i <= 31; i++) {
					if(((60+m)-1+i) % 7 == 0 ) {
						System.out.println(i);
					}else {
						
						System.out.print(i+"\t");
					}
				}
				break;