JobLogDataSet.JobLogDataTable t = new JobLogDataSet.JobLogDataTable();

            // 每天一个日志文件(.XML 文件)，日志的文件名称为：JobLog yyyy-MM-dd.xml
            string jobLogFile = AppDomain.CurrentDomain.BaseDirectory + "JobLog " +
                DateTime.Today.ToString("yyyy-MM-dd") + ".xml";
            if (!File.Exists(jobLogFile))
                t.WriteXml(jobLogFile);

            // 从 .XML 文件中读取日志
            t.ReadXml(jobLogFile);

            // 添加一条日志
            JobLogDataSet.JobLogRow r = t.NewJobLogRow();
            r.TraceLevel = logType.ToString();
            r.User = user;
            r.Datetime = DateTime.Now;
            r.Module = module;
            r.Function = function;
            r.Message = message;
            t.AddJobLogRow(r);

            // 保存到日志到 XML 文件
            t.WriteXml(jobLogFile);
        }
        catch (Exception)
        {}
    }
3. 读日志的方法
    /// <summary>
    /// 读日志
    /// </summary>
    /// <returns>返回读取日志的 DataTable</returns>
    public static JobLogDataSet.JobLogDataTable ReadLog()
    {
        JobLogDataSet.JobLogDataTable jobLogDataTable = new JobLogDataSet.JobLogDataTable();
        try
        {
            // 从应用程序文件夹中，获得所有日志文件 JobLog*.xml
            string[] jobLogFiles = Directory.GetFiles(
                AppDomain.CurrentDomain.BaseDirectory, "JobLog*.xml", SearchOption.TopDirectoryOnly);