知识点：
1.闰年的计算方式((year % 4 ==0 && year % 100 ！= 0 )|| year % 400 ==0)
闰年二月份有 29天 平年28 年

public static void main(String[] args) {/*获取用户输入的日期*/Scanner scan = new Scanner(System.in);System.out.println("请输入年份：");int year = scan.nextInt();//存储年份System.out.println("请输入月份：");int month = scan.nextInt();//存储月份System.out.println("请输入日期：");int date = scan.nextInt();//存储日期int monthOfDay = 0;//月份总天数int allDays = 0;//总天数int week = 0;//存储每月第一天是星期几/*输出月历，每个星期一行，从星期日开始至星期六结束*/System.out.println("=========="+year+"年"+month+"月份"+date+"日"+"=========");System.out.println("");System.out.println("");System.out.println("");/*月历核心代码开始*///判断本月一号为星期几;1900年1月1日为星期一//获取1900年到用户输入的年份的总天数for (int i = 1900;i<=year;i++){if ((i % 4 == 0 && i % 100 != 0) || i % 400 == 0){allDays += 366;//闰年 每年则有366天}else{allDays += 365;//平年 每年则有365天}}//获取用户输入年份+月份的天数for (int j = 1;j<month;j++){switch (j){case 2:if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0){allDays += 29;}else {allDays +=28;}break;case 1: case 3: case 5: case 7: case 8: case 10: case 12:allDays += 31;break;default:allDays +=30;break;}}week = allDays % 7;int n;switch (month){case 2: if ((year % 4 == 0 && year % 100 != 0) || year % 400 == 0){monthOfDay = 29;}else {monthOfDay = 28;}case 1: case 3: case 5: case 7: case 8: case 10: case 12:monthOfDay = 31;break;default:monthOfDay = 30;break;}System.out.println(year+"年"+month+"月"+" 月历展示");System.out.println("日\t一\t二\t三\t四\t五\t六");for (int i = 1; i <= week; i++) {                  //满足条件，先\t,如果week=0;则不打印System.out.print("\t");}for ( n = 1; n <= (7 - week); n++) {               //打印月历的第一行System.out.print(n + "\t");}System.out.println();                              //月历第一行打印完成，换行打印第二行，光标进入第二行for (; n <= monthOfDay; n++) {                     //打印后面的月历的内容System.out.print(n + "\t");if ((n + week) % 7 == 0) {                     //打印到星期日就换行，然后继续打印System.out.println();}}System.out.println();/*月历核心代码结束*/}