C#写系统日志

/// <summary>
        /// 写系统日志
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void button2_Click(object sender, EventArgs e)
        {
            string message="刘习金的测试主文本，时间"+DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
            string sourcename = "dnsinfo";
            EventLogEntryType errotype=EventLogEntryType.SuccessAudit;
            try
            {
                EventLog mylog = new EventLog();
                if (!EventLog.SourceExists(sourcename))
                {
                    EventLog.CreateEventSource(sourcename, sourcename);
                }

                mylog.Source = sourcename;

                mylog.MaximumKilobytes = 1024 * 20;

                mylog.ModifyOverflowPolicy(OverflowAction.OverwriteAsNeeded, 30);

                mylog.WriteEntry(message, errotype);
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.Message);
            }
        }