C# 写日志到文件

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.IO;

namespace psms.util
{
    class Log
    {
        /// <summary>
        /// 写日志文件
        /// </summary>
        /// <param name="sMsg"></param>
        public static void WriteLog(string sMsg)
        {
            if (sMsg != "")
            {
                //Random randObj = new Random(DateTime.Now.Millisecond);
                //int file = randObj.Next() + 1;
                string filename = DateTime.Now.ToString("yyyyMM") + ".log";
                try
                {
                    FileInfo fi = new FileInfo(Application.StartupPath + "\\log\\" + filename);
                    if (!fi.Exists)
                    {
                        using (StreamWriter sw = fi.CreateText())
                        {
                            sw.WriteLine(DateTime.Now + "\n" + sMsg + "\n");
                            sw.Close();
                        }
                    }
                    else
                    {
                        using (StreamWriter sw = fi.AppendText())
                        {
                            sw.WriteLine(DateTime.Now + "\n" + sMsg + "\n");
                            sw.Close();
                        }
                    }
                }
                catch(Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
            }
        }
    }
}