C#实现一个简单的日志类

目录

• 自定义日志类
• NLog版本的日志类
• Serilog版本的日志类

上个月换工作，新项目又要重新搭建基础框架，把日志实现部分单独记录下来方便以后参考。

自定义日志类

代码大部分使用ChatGPT生成，人工进行了测试和优化，主要特点：

• 线程安全，日志异步写入文件不影响业务逻辑
• 支持过期文件自动清理，也可自定义清理逻辑
• 缓存队列有内存上限防呆，防止异常情况下内存爆满
• 提供默认的静态日志记录器，也支持自定义多个日志记录器
• 通过委托方法支持日志文件名、日志记录格式的自定义，更加自由

使用方法：

//正常写入日志
LogManager.Info("This is an info message: {0}", "TestInfo");
LogManager.Debug("This is a debug message: {0}", "TestDebug");
LogManager.Warn("This is an warning message: {0}", "TestInfo");
LogManager.Error("This is a error message: {0}", "TestDebug");

//自定义写入日志，一般情况下使用枚举定义日志记录器的名称
var logger = LogManager.GetLogger("测试日志");
logger.Info("This is an info message: {0}", "TestInfo");
logger.Debug("This is a debug message: {0}", "TestDebug");
logger.Warn("This is an warning message: {0}", "TestInfo");
logger.Error("This is a error message: {0}", "TestDebug");

// 在程序退出前关闭所有日志记录器，默认超时时间是3秒
LogManager.Close(5);

//调试时偶尔使用
if (LogManager.LastException != null)
{
    Console.WriteLine("日志异常:" + LogManager.LastException);
}

配置方法(一般情况下使用默认配置即可)：

//自定义日志保存路径，默认保存到程序启动目录下的Log文件夹
LogManager.CustomLogPath = () => AppDomain.CurrentDomain.BaseDirectory + "\\CustomLogs";
//自定义日志文件名称，默认文件名为 DateTime.Now.ToString("yyyy-MM-dd") + ".log"
LogManager.CustomLogFileName = () => "MyLog_" + DateTime.Now.ToString("yyyyMMdd") + ".log";
//日志保存天数，默认30天
LogManager.SaveDays = 10;
//日志记录的格式，默认为 $"[{Time:yyyy-MM-dd HH:mm:ss ffff}] [{Level.ToString().ToUpper()}] [{ThreadId}] {Message}"
LogManager.LogFormatter = (item) =>
{
    //可以在这里做日志等级筛选，如果返回string.Empty这该条日志不会记录到文件
    return $"{item.Time:yyyy/MM/dd HH:mm:ss.fff} | {item.Level} | T{item.ThreadId:0000} | {item.Message}";
};
//日志回调，可用于界面实时显示日志或日志保存其它存储介质
LogManager.OnWriteLog = (item) => Console.WriteLine("An event was logged: " + item.ToString());

日志类完整代码：

using System;
using System.Collections.Concurrent;
using System.IO;
using System.Threading;
using System.Threading.Tasks;

/// <summary>
/// 日志组件，内部维护了一个静态日志记录类
/// </summary>
public static class LogManager
{
    /// <summary>
    /// 日志等级
    /// </summary>
    public enum LogLevel
    { Debug, Info, Warn, Error, Fatal }

    /// <summary>
    /// 日志数据
    /// </summary>
    public class LogItem
    {
        public LogItem(LogLevel level, string message)
        {
            Level = level;
            Message = message;
            Time = DateTime.Now;
            ThreadId = Thread.CurrentThread.ManagedThreadId;
        }

        public DateTime Time { get; private set; }
        public LogLevel Level { get; private set; }
        public int ThreadId { get; private set; }
        public string Message { get; private set; }

        public override string ToString()
        {
            return $"[{Time:yyyy-MM-dd HH:mm:ss ffff}] [{Level.ToString().ToUpper()}] [{ThreadId}] {Message}";
        }
    }

    /// <summary>
    /// 线程安全异步日志基础类，默认缓存10000条日志，超出时日志会阻塞
    /// </summary>
    public class Logger
    {
        /// <summary>
        /// 日志文件存储路径的委托
        /// </summary>
        public Func<string> CustomLogPath { get; set; }

        /// <summary>
        /// 日志文件名的委托，文件扩展名必须是log，否则会影响日志文件的自动清理（可以自定义清理的方法）
        /// </summary>
        public Func<string> CustomLogFileName { get; set; }

        /// <summary>
        /// 日志文件保存时间
        /// </summary>
        public int SaveDays { get; set; } = 30;

        /// <summary>
        /// 日志格式化委托实例
        /// </summary>
        public Func<LogItem, string> LogFormatter { get; set; }

        /// <summary>
        /// 写日志事件
        /// </summary>
        public Action<LogItem> OnWriteLog { get; set; }

        /// <summary>
        /// 日志清理委托实例，传入日志保存时间
        /// </summary>
        public Action<int> LogCleanup { get; set; }

        /// <summary>
        /// 最后一次异常（仅调试时用，不用于正常业务流程）
        /// </summary>
        public Exception LastException { get; set; }

        // 线程安全的日志队列
        private BlockingCollection<string> logQueue = new BlockingCollection<string>(10000);

        // 标识是否允许写入新日志
        private bool allowNewLogs = true;

        public Logger()
        {
            Task.Factory.StartNew(WriteToFile, TaskCreationOptions.LongRunning);
        }

        // 添加日志至队列方法
        public void EnqueueLog(LogLevel level, string message)
        {
            if (!allowNewLogs) return;
            LogItem item = new LogItem(level, message);

            string logMessage;
            if (LogFormatter != null)
            {
                logMessage = LogFormatter(item);
            }
            else
            {
                logMessage = item.ToString();
            }
            if (!string.IsNullOrWhiteSpace(logMessage))
            {
                logQueue.Add(logMessage);
            }
            OnWriteLog?.Invoke(item);
        }

        // 循环写入写日志到文件
        private void WriteToFile()
        {
            string logPath = CustomLogPath?.Invoke() ?? AppDomain.CurrentDomain.BaseDirectory + "\\Log";
            DirectoryInfo logDir = Directory.CreateDirectory(logPath);

            while (true)
            {
                try
                {
                    if (!allowNewLogs && logQueue.Count == 0) break;

                    string logMessage;
                    if (logQueue.TryTake(out logMessage, TimeSpan.FromSeconds(1)))
                    {
                        string fileName = CustomLogFileName?.Invoke() ?? DateTime.Now.ToString("yyyy-MM-dd") + ".log";
                        if (!File.Exists(fileName))
                        {
                            // 清理旧日志
                            if (LogCleanup != null)
                            {
                                LogCleanup(SaveDays);
                            }
                            else
                            {
                                CleanUpOldLogs(logDir, SaveDays);
                            }
                        }
                        File.AppendAllText(Path.Combine(logPath, fileName), logMessage + Environment.NewLine);
                    }
                }
                catch (Exception ex)
                {
                    LastException = ex;
                    Console.WriteLine("Logger Exception - WriteToFile : " + ex.Message);
                }
            }

        }

        /// <summary>
        /// 关闭日志器方法，指定超时时间（秒）
        /// </summary>
        /// <param name="waitTimeInSeconds">等待时间</param>
        public void Close(int waitTimeInSeconds = 3)
        {
            allowNewLogs = false;
            CancellationTokenSource cts = new CancellationTokenSource(TimeSpan.FromSeconds(waitTimeInSeconds));
            try
            {
                CancellationToken token = cts.Token;
                // 标识队列已完成添加
                logQueue.CompleteAdding();

                while (!token.IsCancellationRequested)
                {
                    if (logQueue.Count == 0) break; // 提前退出

                    // 短暂休眠以降低 CPU 占用
                    Task.Delay(100, token).Wait();
                }
            }
            catch (OperationCanceledException)
            {
                // 等待时间到，退出方法，不传播异常
            }
            catch (Exception ex)
            {
                Console.WriteLine("An unexpected exception occurred in the Close method: " + ex.Message);
            }
        }

        /// <summary>
        /// 默认的清理过期日志的方法
        /// </summary>
        /// <param name="logDir"></param>
        /// <param name="saveDays"></param>
        public static void CleanUpOldLogs(DirectoryInfo logDir, int saveDays)
        {
            FileInfo[] logFiles = logDir.GetFiles("*.log");
            foreach (FileInfo file in logFiles)
            {
                if (DateTime.Now - file.CreationTime >= TimeSpan.FromDays(saveDays))
                {
                    file.Delete();
                }
            }
        }

        /// <summary>
        /// 记录Info等级日志
        /// </summary>
        /// <param name="message"></param>
        /// <param name="args"></param>
        public void Info(string message, params object[] args)
        {
            EnqueueLog(LogLevel.Info, string.Format(message, args));
        }

        /// <summary>
        /// 记录Debug等级日志
        /// </summary>
        /// <param name="message"></param>
        /// <param name="args"></param>
        public void Debug(string message, params object[] args)
        {
            EnqueueLog(LogLevel.Debug, string.Format(message, args));
        }

        /// <summary>
        /// 记录Warning等级日志
        /// </summary>
        /// <param name="message"></param>
        /// <param name="args"></param>
        public void Warn(string message, params object[] args)
        {
            EnqueueLog(LogLevel.Warn, string.Format(message, args));
        }

        /// <summary>
        /// 记录Error等级日志
        /// </summary>
        /// <param name="message"></param>
        /// <param name="args"></param>
        public void Error(string message, params object[] args)
        {
            EnqueueLog(LogLevel.Error, string.Format(message, args));
        }

        /// <summary>
        /// 记录Fatal等级日志
        /// </summary>
        /// <param name="message"></param>
        /// <param name="args"></param>
        public void Fatal(string message, params object[] args)
        {
            EnqueueLog(LogLevel.Fatal, string.Format(message, args));
        }
    }

    private static Logger logger = new Logger();
    private static ConcurrentDictionary<string, Logger> logDic = new ConcurrentDictionary<string, Logger>();

    /// <summary>
    /// 获取自定义的日志记录类
    /// </summary>
    /// <param name="name"></param>
    /// <returns></returns>
    public static Logger GetLogger(string name)
    {
        return logDic.GetOrAdd(name, key =>
        {
            var log = new Logger();
            log.CustomLogPath = () => AppDomain.CurrentDomain.BaseDirectory + "\\Log\\" + key;
            return log;
        });
    }

    /// <summary>
    /// 日志文件存储路径的委托
    /// </summary>
    public static Func<string> CustomLogPath
    {
        get => logger.CustomLogPath;
        set => logger.CustomLogPath = value;
    }

    /// <summary>
    /// 日志文件名的委托，文件扩展名必须是log，否则会影响日志文件的自动清理（可以自定义清理的方法）
    /// </summary>
    public static Func<string> CustomLogFileName
    {
        get => logger.CustomLogFileName;
        set => logger.CustomLogFileName = value;
    }

    /// <summary>
    /// 日志文件保存时间
    /// </summary>
    public static int SaveDays
    {
        get => logger.SaveDays;
        set => logger.SaveDays = value;
    }

    /// <summary>
    /// 日志格式化委托实例
    /// </summary>
    public static Func<LogItem, string> LogFormatter
    {
        get => logger.LogFormatter;
        set => logger.LogFormatter = value;
    }

    /// <summary>
    /// 写日志事件
    /// </summary>
    public static Action<LogItem> OnWriteLog
    {
        get => logger.OnWriteLog;
        set => logger.OnWriteLog = value;
    }

    /// <summary>
    /// 日志清理委托实例，传入日志保存时间
    /// </summary>
    public static Action<int> LogCleanup
    {
        get => logger.LogCleanup;
        set => logger.LogCleanup = value;
    }

    /// <summary>
    /// 最后一次异常（仅调试时用，不用于正常业务流程）
    /// </summary>
    public static Exception LastException
    {
        get => logger.LastException;
        set => logger.LastException = value;
    }

    /// <summary>
    /// 关闭所有日志记录器，指定超时时间（秒），日志记录器较多时可能耗时较久
    /// </summary>
    /// <param name="waitTimeInSeconds">等待时间</param>
    public static void Close(int waitTimeInSeconds = 3)
    {
        logger.Close(waitTimeInSeconds);
        foreach (var item in logDic.Values)
        {
            item.Close(waitTimeInSeconds);
        }
    }

    /// <summary>
    /// 记录Info等级日志
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Info(string message, params object[] args)
    {
        logger.EnqueueLog(LogLevel.Info, string.Format(message, args));
    }

    /// <summary>
    /// 记录Debug等级日志
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Debug(string message, params object[] args)
    {
        logger.EnqueueLog(LogLevel.Debug, string.Format(message, args));
    }

    /// <summary>
    /// 记录Warning等级日志
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Warn(string message, params object[] args)
    {
        logger.EnqueueLog(LogLevel.Warn, string.Format(message, args));
    }

    /// <summary>
    /// 记录Error等级日志
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Error(string message, params object[] args)
    {
        logger.EnqueueLog(LogLevel.Error, string.Format(message, args));
    }

    /// <summary>
    /// 记录Fatal等级日志
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Fatal(string message, params object[] args)
    {
        logger.EnqueueLog(LogLevel.Fatal, string.Format(message, args));
    }
}

NLog版本的日志类

有时候因为公司或团队原因必须使用NLog日志库，这里提供一个简单的NLog版本的日志类，日志规则基本和上面的自定义类一致。

使用方法如下：

//可以指定日志保存天数，默认30天
Logger.Init();
//订阅写日志事件
Logger.GetLogEventTarget().LogReceived += Logger_LogWrite;
//记录日志
Logger.Info("软件启动");

NLog版本的日志类只是对NLog的常用配置做一个封装，如果需要自定义日志格式或存储位置需要自己改封装部分的代码。

完整代码：

using NLog;
using NLog.Config;
using NLog.Layouts;
using NLog.Targets;
using NLog.Targets.Wrappers;
using System;

/// <summary>
/// 全局日志类
/// </summary>
public static class Logger
{
    #region 私有字段方法

    private static ILogger logger;

    private static void ConfigureNLog(int saveDays = 30)
        {
            var config = new LoggingConfiguration();

            // 创建目标（这里是 FileTarget 用于写入文件）
            var fileTarget = new FileTarget("logfile")
            {
                FileName = "${basedir}/Log/${date:format=yyyy-MM-dd}.log",
                Layout = "${longdate} ${uppercase:${level}} ${message}  ${exception:format=tostring}",
                ArchiveOldFileOnStartup = true,
                ArchiveEvery = FileArchivePeriod.Day,
                MaxArchiveFiles = saveDays,
            };

            // 使用 AsyncTargetWrapper 实现异步写日志
            var asyncFileTarget = new AsyncTargetWrapper(fileTarget, 1000, AsyncTargetWrapperOverflowAction.Discard);
            // 设置规则
            var rule = new LoggingRule("*", LogLevel.Debug, asyncFileTarget);
            config.LoggingRules.Add(rule);

            // 创建自定义Target
            var logEventTarget = new LogEventTarget
            {
                Name = "logEvent",
                MessageLayout = "${longdate}  ${uppercase:${level}} ${message}  ${exception:format=tostring}"
            };
            config.AddTarget(logEventTarget);

            // 添加规则
            var eventRule = new LoggingRule("*", LogLevel.Debug, logEventTarget);
            config.LoggingRules.Add(eventRule);

            // 应用配置
            LogManager.Configuration = config;
        }

    #endregion 私有字段方法

    #region 公共字段方法

    /// <summary>
    /// 初始化日志，程序初始化时启动
    /// </summary>
    /// <param name="saveDays"></param>
    public static void Init(int saveDays = 30)
    {
        ConfigureNLog(saveDays);
        logger = LogManager.GetCurrentClassLogger();
    }

    /// <summary>
    /// 获取日志回调Target
    /// </summary>
    /// <returns></returns>
    public static LogEventTarget GetLogEventTarget()
    {
        return (LogEventTarget)LogManager.Configuration.FindTargetByName("logEvent");
    }

    /// <summary>
    /// 关闭日志，程序退出时调用
    /// </summary>
    public static void Close()
    {
        LogManager.Flush();
        LogManager.Shutdown();
    }

    #endregion 公共字段方法

    #region 日志接口

    /// <summary>
    /// 跟踪日志级别：最详细的级别，用于开发，很少用于生产。
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Trace(string message, params object[] args)
    {
        logger.Trace(message, args);
    }

    /// <summary>
    /// 调试日志级别：根据感兴趣的内部事件调试应用程序行为。
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Debug(string message, params object[] args)
    {
        logger.Debug(message, args);
    }

    /// <summary>
    /// 信息日志级别：突出显示进度或应用程序生存期事件的信息。
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Info(string message, params object[] args)
    {
        logger.Info(message, args);
    }

    /// <summary>
    /// 警告日志级别：关于可以恢复的验证问题或临时故障的警告。
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Warn(string message, params object[] args)
    {
        logger.Warn(message, args);
    }

    /// <summary>
    /// 错误日志级别：功能失败或捕捉到System.Exception的错误。
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Error(string message, params object?[] args)
    {
        logger.Error(message, args);
    }

    /// <summary>
    /// 致命日志级别：最关键级别，应用程序即将中止。
    /// </summary>
    /// <param name="message"></param>
    /// <param name="args"></param>
    public static void Fatal(string message, params object[] args)
    {
        logger.Fatal(message, args);
    }

    #endregion 日志接口
}

/// <summary>
/// 日志事件目标
/// </summary>
public class LogEventTarget : Target
{
    /// <summary>
    /// 日志事件
    /// </summary>
    public event EventHandler<string> LogReceived;
    /// <summary>
    /// 日志布局
    /// </summary>
    [RequiredParameter]
    public Layout MessageLayout { get; set; }
    protected override void Write(LogEventInfo logEvent)
    {
        string logMessage = MessageLayout.Render(logEvent);
        OnLogReceived(logMessage);
    }
    private void OnLogReceived(string message)
    {
        LogReceived?.Invoke(this, message);
    }
}

Serilog版本的日志类

Serilog 是用于 .NET 应用程序的诊断日志记录库。它易于设置，具有干净的 API，并且可以在所有最新的 .NET 平台上运行。

github链接:Serilog

安装以下NuGet包：

使用方法如下：

Log.Logger = new LoggerConfiguration()
    .MinimumLevel.Debug()
    .WriteTo.Console()
    //异步写入，滚动间隔：天，默认情况下只保留最近的 31 个文件
    .WriteTo.Async(a => a.File("logs/log-.txt", rollingInterval: RollingInterval.Day, retainedFileCountLimit: 60))
    .WriteTo.MySink()
    .CreateLogger();

Log.Information("Hello, world!");

// 最后，在应用程序退出之前。。。
Log.CloseAndFlush();

自定义日志计算器如下：

public class MySink : ILogEventSink
{
    private readonly IFormatProvider _formatProvider;

    public MySink(IFormatProvider formatProvider)
    {
        _formatProvider = formatProvider;
    }

    public void Emit(LogEvent logEvent)
    {
        var message = logEvent.RenderMessage(_formatProvider);
        //自己实现写入到界面控件或其它日志中心
        Console.WriteLine(DateTimeOffset.Now.ToString() + " " + message);
    }
}

public static class MySinkExtensions
{
    public static LoggerConfiguration MySink(
              this LoggerSinkConfiguration loggerConfiguration,
              IFormatProvider formatProvider = null)
    {
        return loggerConfiguration.Sink(new MySink(formatProvider));
    }
}