.NET判断某一年的所有放假的日期

由于工作需求写的一个程序，判断某一年所有的放假日期，根据国家的法定假日和补休日期进行的判断。

        protected void Button1_Click(object sender, EventArgs e)
        {
            string sql = "";
            //2015年1月1日的星期数
            int year = 2015;
            int week = 4;
            for (int month = 1; month <= 12; month++)
            {
                int day = 31;
                switch (month)
                {
                    case 2:
                        if (IsLeapYear(year))
                        {
                            day = 29;
                        }
                        else
                        {
                            day = 28;
                        }
                        break;
                    case 4:
                        day = 30;
                        break;
                    case 6:
                        day = 30;
                        break;
                    case 9:
                        day = 30;
                        break;
                    case 11:
                        day = 30;
                        break;
                }
                for (int a = 1; a <= day; a++)
                {
                    string time = string.Format("{0}-{1}-{2}", year, month, a);
                    if (week == 7 || checkfangjia(time))
                    {
                        if (!bufangjia(time))
                        {

                            string m = string.Format("INSERT INTO [dbo].[tm_holidays] ([id], [year], [date]) VALUES (N‘" + year + "‘, N‘{0} 00:00:00.000‘);</br>", time);
                            sql += m;
                            Response.Write(m);
                            //Response.Write("2015年" + month + "月" + a + "日" + "星期" + week + "</br>");
                        }
                    }
                    if (week == 7)
                    {
                        week = 1;
                    }
                    else
                    {
                        week++;
                    }
                }
            }
        }
        //判断某一天是否放假
        public bool checkfangjia(string day)
        {
            //所有放假的日期
            string[] fangjia = { "2015-1-1", "2015-1-2", "2015-1-3", "2015-2-18", "2015-2-19", "2015-2-20", "2015-2-21", "2015-2-22", "2015-2-23", "2015-2-24", "2015-4-4", "2015-4-5", "2015-4-6", "2015-5-1", "2015-5-2", "2015-5-3", "2015-6-20", "2015-6-21", "2015-6-22", "2015-9-26", "2015-9-27", "2015-10-1", "2015-10-2", "2015-10-3", "2015-10-4", "2015-10-5", "2015-10-6", "2015-10-7" };
            foreach (string s in fangjia)
            {
                if (s.Equals(day))
                {
                    return true;
                }
            }
            return false;
        }
        //判断某一天是否调休
        public bool bufangjia(string day)
        {
            //与周六 周日调休的日期
            string[] bufangjia = { "2015-1-4", "2015-2-15", "2015-2-28", "2015-10-10" };
            foreach (string s in bufangjia)
            {
                if (s.Equals(day))
                {
                    return true;
                }
            }
            return false;
        }
        //判断平年还是闰年
        private bool IsLeapYear(int year)
        {
            if (year % 100 == 0)
            {
                if (year % 400 == 0)
                {
                    return true;
                }
            }
            else
            {
                if (year % 4 == 0)
                {
                    return true;
                }
            }
            return false;
        }