java 获取上个月的日期 java获取当月每天的日期号

import java.time.DayOfWeek;
import java.time.LocalDate;

public class Demo02 {
    public static void main(String[] args) {
        LocalDate date = LocalDate.now();  //当前的年月日
        int month = date.getMonthValue();  //获取当前月份
        int day = date.getDayOfMonth();  //获取当前几号

        date = date.minusDays(day - 1);  //将date设置为当月第一天，minusDays()是减去指定天数 3-(3-1)
        DayOfWeek weekday = date.getDayOfWeek();  //得到这一天为星期几

        // 1 = Monday  2=Tuesday.....  7 = Sunday
        int value = weekday.getValue();

        System.out.println("Mon Tue Wed Thu Fri Sat Sun");
        for (int i = 1; i < value; i++) {
            System.out.print("    ");
        }

        while (date.getMonthValue() == month) {  //循环条件为当月
            System.out.printf("%3d",date.getDayOfMonth()); //打印当前几号
            if(date.getDayOfMonth() == day) {
                System.out.print("*");  //对今天进行标记
            } else {
                System.out.print(" ");
            }

            date = date.plusDays(1); //天数 +1

            if(date.getDayOfWeek().getValue() == 1) {  //如果达到新周的第一天
                System.out.println(); //换行
            }
        }
    }
}

//以下为输出结果
/*
Mon Tue Wed Thu Fri Sat Sun
      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 
Process finished with exit code 0
*/