csharp C＃超级简单记录器类//用法示例：https：//heiswayi.nrird.com/2016/creating-super-simple-logger-class-in-csharp

Posted 2021-05-12

public class SimpleLogger
{
    private readonly string datetimeFormat;
    private readonly string logFilename;

    /// <summary>
    /// Initiate an instance of SimpleLogger class constructor.
    /// If log file does not exist, it will be created automatically.
    /// </summary>
    public SimpleLogger()
    {
        datetimeFormat = "yyyy-MM-dd HH:mm:ss.fff";
        logFilename = System.Reflection.Assembly.GetExecutingAssembly().GetName().Name + ".log";

        // Log file header line
        string logHeader = logFilename + " is created.";
        if (!System.IO.File.Exists(logFilename))
        {
            WriteLine(System.DateTime.Now.ToString(datetimeFormat) + " " + logHeader, false);
        }
    }

    /// <summary>
    /// Log a DEBUG message
    /// </summary>
    /// <param name="text">Message</param>
    public void Debug(string text)
    {
        WriteFormattedLog(LogLevel.DEBUG, text);
    }

    /// <summary>
    /// Log an ERROR message
    /// </summary>
    /// <param name="text">Message</param>
    public void Error(string text)
    {
        WriteFormattedLog(LogLevel.ERROR, text);
    }

    /// <summary>
    /// Log a FATAL ERROR message
    /// </summary>
    /// <param name="text">Message</param>
    public void Fatal(string text)
    {
        WriteFormattedLog(LogLevel.FATAL, text);
    }

    /// <summary>
    /// Log an INFO message
    /// </summary>
    /// <param name="text">Message</param>
    public void Info(string text)
    {
        WriteFormattedLog(LogLevel.INFO, text);
    }

    /// <summary>
    /// Log a TRACE message
    /// </summary>
    /// <param name="text">Message</param>
    public void Trace(string text)
    {
        WriteFormattedLog(LogLevel.TRACE, text);
    }

    /// <summary>
    /// Log a WARNING message
    /// </summary>
    /// <param name="text">Message</param>
    public void Warning(string text)
    {
        WriteFormattedLog(LogLevel.WARNING, text);
    }

    private void WriteFormattedLog(LogLevel level, string text)
    {
        string pretext;
        switch (level)
        {
            case LogLevel.TRACE:
                pretext = System.DateTime.Now.ToString(datetimeFormat) + " [TRACE]   ";
                break;
            case LogLevel.INFO:
                pretext = System.DateTime.Now.ToString(datetimeFormat) + " [INFO]    ";
                break;
            case LogLevel.DEBUG:
                pretext = System.DateTime.Now.ToString(datetimeFormat) + " [DEBUG]   ";
                break;
            case LogLevel.WARNING:
                pretext = System.DateTime.Now.ToString(datetimeFormat) + " [WARNING] ";
                break;
            case LogLevel.ERROR:
                pretext = System.DateTime.Now.ToString(datetimeFormat) + " [ERROR]   ";
                break;
            case LogLevel.FATAL:
                pretext = System.DateTime.Now.ToString(datetimeFormat) + " [FATAL]   ";
                break;
            default:
                pretext = "";
                break;
        }

        WriteLine(pretext + text);
    }

    private void WriteLine(string text, bool append = true)
    {
        try
        {
            using (System.IO.StreamWriter writer = new System.IO.StreamWriter(logFilename, append, System.Text.Encoding.UTF8))
            {
                if (text != "")
                {
                    writer.WriteLine(text);
                }
            }
        }
        catch
        {
            throw;
        }
    }

    [System.Flags]
    private enum LogLevel
    {
        TRACE,
        INFO,
        DEBUG,
        WARNING,
        ERROR,
        FATAL
    }
}