package com.ruoyi.receipt.utils;

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

public class DateUtil {

    public static void main(String[] args) throws ParseException {

        SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");

        //获取本月的天数
        Calendar calendar1 = Calendar.getInstance();
        calendar1.set(Calendar.DATE, 1);
        calendar1.roll(Calendar.DATE, -1);
        System.out.println("本月有:=>"+calendar1.get(Calendar.DATE));
        int month1 = calendar1.get(Calendar.MONTH);
        int resultMonth1=month1+1;
        System.out.println("本月的月份为:=>"+resultMonth1);

        //根据年月获取对应的天数
        Calendar calendar2 = Calendar.getInstance();
        // 指定一个日期
        Date date2 = dateFormat.parse("2021-05-31 00:00:00");
        calendar2.setTime(date2);
        calendar2.set(Calendar.DATE, 1);
        calendar2.roll(Calendar.DATE, -1);
        System.out.println("指定日期月的天数:=>"+calendar2.get(Calendar.DATE));


        //--------------------

        Calendar calendar3 = Calendar.getInstance();
        // 指定一个日期
        Date date3 = dateFormat.parse("2021-05-31 00:00:00");
        calendar3.setTime(date3);

        //获取年份
        System.out.println("获取年份:=>"+calendar3.get(Calendar.YEAR));

        int month3 = calendar3.get(Calendar.MONTH);
        int resultMonth3=month3+1;
        System.out.println("获取月份:=>"+resultMonth3);

        //获取当前天数
        System.out.println("获取当前天数:=>"+calendar3.get(Calendar.DAY_OF_MONTH));

        //获取本月最小天数
        System.out.println("获取本月最小天数:=>"+calendar3.getActualMinimum(Calendar.DAY_OF_MONTH));

        //获取本月最大天数
        System.out.println("获取本月最大天数:=>"+calendar3.getActualMaximum(Calendar.DAY_OF_MONTH));

        //获取指定日期是本周几
        int week = calendar3.get(Calendar.DAY_OF_WEEK);
        int resultWeek=week-1;
        System.out.println("获取指定日期是本周几:=>" + resultWeek);

        //获取指定日期是当前月的第几天
        System.out.println("获取指定日期是当前月的第几天:=>" + calendar3.get(Calendar.DAY_OF_MONTH));

        //获取指定日期是当前年的第几天
        System.out.println("获取指定日期是当前年的第几天:=>" + calendar3.get(Calendar.DAY_OF_YEAR));

        //指定日期+1天
        calendar3.add(Calendar.DATE, 1); //增加一天
        System.out.println("指定日期+1天:=>"+dateFormat.format(calendar3.getTime()));

        //指定日期-2天
        calendar3.add(Calendar.DATE, -2); //减小两天
        System.out.println("指定日期-2天:=>"+dateFormat.format(calendar3.getTime()));

        //格式化日期
        System.out.println("格式化日期:=>"+dateFormat.format(calendar3.getTime()));

        //将当前日期设置为11号
        calendar3.set(Calendar.DATE,11);
        System.out.println("将当前日期设置为11号:=>"+dateFormat.format(calendar3.getTime()));
    }

}