向日期添加天数，但不超过一年的最后一天

import datetime

def add_days_to_date(date_str, days):
    # 将日期字符串转换为日期对象
    date_obj = datetime.datetime.strptime(date_str, "%Y-%m-%d")
    
    # 添加给定天数到日期
    new_date = date_obj + datetime.timedelta(days=days)
    
    # 获取新日期的年、月、日
    new_year = new_date.year
    new_month = new_date.month
    new_day = new_date.day
    
    # 判断是否需要对月份进行调整
    if new_month > 12:
        new_month = 12
    
    # 判断是否需要对日期进行调整
    if new_day > 28:
        # 获取新日期所在月份的最大天数
        max_day = max_days_in_month(new_year, new_month)
        
        if new_day > max_day:
            new_day = max_day
    
    # 格式化调整后的年、月、日为日期字符串
    new_date_str = "{:04d}-{:02d}-{:02d}".format(new_year, new_month, new_day)
    
    return new_date_str

def max_days_in_month(year, month):
    if month in [4, 6, 9, 11]:
        return 30
    elif month == 2:
        if is_leap_year(year):
            return 29
        else:
            return 28
    else:
        return 31

def is_leap_year(year):
    if year % 4 == 0:
        if year % 100 == 0:
            if year % 400 == 0:
                return True
            else:
                return False
        else:
            return True
    else:
        return False

# 测试示例
date = "2022-02-28"
days = 3
new_date = add_days_to_date(date, days)
print(new_date)