.Net Core如何使用Logger实现log写入本地文件系统

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.net core 自带一个基础的logger框架Microsoft.Extensions.Logging。

微软默认实现了Microsoft.Extensions.Logging.Console.dll。控制台的日志输出和Microsoft.Extensions.Logging.Debug.dll调试输出。

logger框架主要几个类：LoggerFactory，Logger，LoggerProvider。

看名字就很好理解，都不需要解释。

实现我们自己的file logger只需要实现logger，loggerProvider即可。

第一步：入口。

loggerFactory.AddFile(this.Configuration.GetSection("FileLogging"));

为LoggerFactory扩张一个方法，提供增加日志写文件方式的入口。相关的配置来自appsettings.JSON

    public static class FileLoggerExtensions    {        //add 日志文件创建规则，分割规则，格式化规则，过滤规则 to appsettings.json        public static ILoggerFactory AddFile(this ILoggerFactory factory, IConfiguration configuration)        {            return AddFile(factory, new FileLoggerSettings(configuration));        }        public static ILoggerFactory AddFile(this ILoggerFactory factory, FileLoggerSettings fileLoggerSettings)        {            factory.AddProvider(new FileLoggerProvider(fileLoggerSettings));            return factory;        }    }

第二步：实现我们的logger提供程序，实现ILoggerProvider接口

public class FileLoggerProvider : ILoggerProvider, Idisposable

关键方法CreateLogger，创建真正写日志的logger。对当前的logger可以做适当的缓存，配置logger

    public class FileLoggerProvider : ILoggerProvider, IDisposable    {        FileLoggerSettings _configuration;        readonly ConcurrentDictionary<string, InitLoggerModel> _loggerKeys = new ConcurrentDictionary<string, InitLoggerModel>();        readonly ConcurrentDictionary<string, FileLogger> _loggers = new ConcurrentDictionary<string, FileLogger>();        public FileLoggerProvider(FileLoggerSettings configuration)        {            _configuration = configuration;            _configuration.ChangeToken.ReGISterChangeCallback(p =>            {                //appsettings.json changed. reload settings.                _configuration.Reload();                //update loggers settings fORM new settings                foreach (var item in this._loggers.Values)                {                    InitLoggerModel model = new InitLoggerModel();                    InitLoggerSettings(item.Name, model);                    InitLogger(model, item);                }            }, null);        }        public ILogger CreateLogger(string cateGoryName)        {            var loggerKey = this._loggerKeys.GetOrAdd(categoryName, p =>             {                 InitLoggerModel model = new InitLoggerModel();                 InitLoggerSettings(categoryName, model);                 return model;             });            var key = loggerKey.FileDiretoryPath + loggerKey.FileNameTemplate;            return this._loggers.GetOrAdd(key, p =>            {                var logger = new FileLogger(categoryName);                InitLogger(loggerKey, logger);                return logger;            });        }        private static void InitLogger(InitLoggerModel model, FileLogger logger)        {            logger.FileNameTemplate = model.FileNameTemplate;            logger.FileDiretoryPath = model.FileDiretoryPath;            logger.MinLevel = model.MinLevel;        }        class InitLoggerModel        {            public LogLevel MinLevel { get; set; }            public string FileDiretoryPath { get; set; }            public string FileNameTemplate { get; set; }            public override int GetHashCode()            {                return this.MinLevel.GetHashCode() + this.FileDiretoryPath.GetHashCode() + this.FileNameTemplate.GetHashCode();            }            public override bool Equals(object obj)            {                var b = obj as InitLoggerModel;                if (b == null)                    return false;                return this.MinLevel == b.MinLevel && this.FileDiretoryPath == b.FileDiretoryPath && this.FileNameTemplate == b.FileNameTemplate;            }        }        private void InitLoggerSettings(string categoryName, InitLoggerModel model)        {            model.MinLevel = LogLevel.Debug;            var keys = this.GeTKEys(categoryName);            foreach (var item in keys)            {                var switchV = _configuration.GetSwitch(item);                if (switchV.Item1)                {                    model.MinLevel = switchV.Item2;                    break;                }            }            model.FileDiretoryPath = this._configuration.DefaultPath;            foreach (var item in keys)            {                var switchV = _configuration.GetDiretoryPath(item);                if (switchV.Item1)                {                    model.FileDiretoryPath = switchV.Item2;                    break;                }            }            model.FileNameTemplate = this._configuration.DefaultFileName;            foreach (var item in keys)            {                var switchV = _configuration.GetFileName(item);                if (switchV.Item1)                {                    model.FileNameTemplate = switchV.Item2;                    break;                }            }        }        IEnumerable<string> GetKeys(string categoryName)        {            while (!String.IsNullOrEmpty(categoryName))            {                // a.b.c                //--result                // a.b.c，a.b，a，Default                yield return categoryName;                var last = categoryName.LastIndexOf('.');                if (last <= 0)                {                    yield return "Default";                    yield break;                }                System.Diagnostics.Debug.WriteLine(categoryName + "--" + last);                categoryName = categoryName.Substring(0, last);            }            yield break;        }        public void Dispose()        {        }    }

第三步：实现我们的logger，实现ILogger接口。真正将log写入file

public class FileLogger : Ilogger

    public class FileLogger : ILogger    {        static protected string delimiter = new string(new char[] { (char)1 });        public FileLogger(string categoryName)        {            this.Name = categoryName;        }        class Disposable : IDisposable        {            public void Dispose()            {            }        }        Disposable _DisposableInstance = new Disposable();        public IDisposable BeginScope<TState>(TState state)        {            return _DisposableInstance;        }        public bool IsEnabled(LogLevel logLevel)        {            return this.MinLevel <= logLevel;        }        public void Reload()        {            _Expires = true;        }        public string Name { get; private set; }        public LogLevel MinLevel { get; set; }        public string FileDiretoryPath { get; set; }        public string FileNameTemplate { get; set; }        public void Log<TState>(LogLevel logLevel, EventId eventId, TState state, Exception exception, Func<TState, Exception, string> formatter)        {            if (!this.IsEnabled(logLevel))                return;            var msg = formatter(state, exception);            this.Write(logLevel, eventId, msg, exception);        }        void Write(LogLevel logLevel, EventId eventId, string message, Exception ex)        {            EnsureInitFile();            //TODO 提高效率 队列写！！！            var log = String.Concat(DateTime.Now.ToString("HH:mm:ss"), '[', logLevel.ToString(), ']', '[',                  Thread.CurrentThread.ManagedThreadId.ToString(), ',', eventId.Id.ToString(), ',', eventId.Name, ']',                  delimiter, message, delimiter, ex?.ToString());            lock (this)            {                this._sw.WriteLine(log);            }        }        bool _Expires = true;        string _FileName;        protected StreamWriter _sw;        void EnsureInitFile()        {            if (CheckNeedCreateNewFile())            {                lock (this)                {                    if (CheckNeedCreateNewFile())                    {                        InitFile();                        _Expires = false;                    }                }            }        }        bool CheckNeedCreateNewFile()        {            if (_Expires)            {                return true;            }            //TODO 使用 RollingType判断是否需要创建文件。提高效率！！！            if (_FileName != DateTime.Now.ToString(this.FileNameTemplate))            {                return true;            }            return false;        }        void InitFile()        {            if (!Directory.Exists(this.FileDiretoryPath))            {                Directory.CreateDirectory(this.FileDiretoryPath);            }            var path = "";            int i = 0;            do            {                _FileName = DateTime.Now.ToString(this.FileNameTemplate);                path = Path.Combine(this.FileDiretoryPath, _FileName + "_" + i + ".log");                i++;            } while (System.IO.File.Exists(path));            var oldsw = _sw;            _sw = new StreamWriter(new FileStream(path, FileMode.CreateNew, FileAccess.ReadWrite, FileShare.Read), Encoding.UTF8);            _sw.AutoFlush = true;            if (oldsw != null)            {                try                {                    _sw.Flush();                    _sw.Dispose();                }                catch                {                }            }        }    }

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