按类别和日期保存文件类

下面实现按类别和日期来存放文件.，代码如下

 public class CategoryFile    {        string path = "D:";        const string ch = "\\";        /// <summary>        /// 文件保存地址        /// </summary>        public String PATH        {            set { path = value; }            get { return path; }        }        string log = string.Empty;        /// <summary>        /// 错误信息，只读属性        /// </summary>        public string LOG        {            get { return log; }        }        /// <summary>        ///按类别保存文件        /// </summary>        /// <param name="value">要保存的内容</param>        /// <param name="category">要保存的类别</param>        public void SaveFile(string value, string category)        {            StreamWriter sw = null;            try            {                string identity = DateTime.Now.ToString("yyyyMMdd");                string hour = DateTime.Now.Hour.ToString();                string parentPath = path + ch + identity;                string childPath = parentPath + ch + category + ch + hour;                if (!System.IO.Directory.Exists(DateTime.Now.Year.ToString()))                {                    Directory.CreateDirectory(parentPath);                }                if (!Directory.Exists(childPath))                {                    Directory.CreateDirectory(childPath);                }                sw = new StreamWriter(childPath + ch + DateTime.Now.ToString("yyyyMMddHHmmss"));                sw.Write(value);                sw.Close();                sw = null;            }            catch (IOException e)            {                log = e.Message;            }            catch (Exception e1)            {                log = e1.Message;            }            finally            {                if (sw != null)                    sw.Close();            }        }    }