.Net Core 实践

实现目标：将log4net的相关操作封装成一个 .Net Standard类库
demo地址：https://github.com/PuzzledAlien/log4net_demo/tree/master/DotNetCoreConsole_V2

Step 1 建立解决方案和处理项目相关配置

在当前解决方案下新建项目，选择 .Net Standard类库，命名“MyLogManager”

nuget引用log4net，添加log4net.config配置，右键点击log4net.config，选择“属性”，修改log4net.config文件属性
刚添加的log4net.config文件属性可能如下图所示（生成操作为无，不复制到输出目录）

需要修改成如下所示（生成操作 无 改为 内容 ，复制到输出目录 - 选择 如果较新则复制）

重新生成解决方案后，在生成目录中就能看到log4net.config文件

Step 2 上代码

思路：两个StartLogger方法，在程序启动时启动该方法，一个方法自己配置处理，一个走默认
代码如下

    public class MyLogManager
    {
        private static ILoggerRepository _loggerRepository;

        /// <summary>
        /// 启动logger
        /// </summary>
        /// <param name="repository">repository名称</param>
        /// <param name="fileName">配置文件名称</param>
        public static void StartLogger(string repository, string fileName)
        {
            _loggerRepository = LogManager.CreateRepository(repository);
            XmlConfigurator.ConfigureAndWatch(_loggerRepository, new FileInfo(fileName));
        }

        /// <summary>
        /// 启动logger
        /// </summary>
        public static void StartLogger()
        {
            _loggerRepository = LogManager.CreateRepository(nameof(MyLogManager));
            XmlConfigurator.ConfigureAndWatch(_loggerRepository, new FileInfo("log4net.config"));
        }

        public static ILog GetMyLog<T>(T t)
        {
            return LogManager.GetLogger(_loggerRepository.Name, t.GetType());
        }

        public static ILog GetMyLog(object obj)
        {
            return LogManager.GetLogger(_loggerRepository.Name, obj.GetType());
        }

        public static ILog GetMyLog(Type type)
        {
            return LogManager.GetLogger(_loggerRepository.Name, type);
        }
    }

封装之后，调用代码会比第一版本的稍微精简

        static void TestV1()
        {
            MyLogManager.MyLogManager.StartLogger("DotNetCoreConsole_V2", "log4net.config");

            var log = MyLogManager.MyLogManager.GetMyLog(typeof(Program));

            const int numberOfCycles = 20000;

            var sw = Stopwatch.StartNew();
            for (var i = 0; i < numberOfCycles; i++)
            {
                log.InfoFormat("testNum: {0} ", i);
            }
            sw.Stop();

            Console.WriteLine();
            Console.WriteLine("Ellapsed: {0}, numPerSec: {1}", sw.ElapsedMilliseconds, numberOfCycles / (sw.ElapsedMilliseconds / (double)1000));
            Console.ReadKey();
        }

代码重构和优化

思考：可不可以去掉StartLogger这行代码呢？可以。
实现如下

    public class NullLogManager
    {
        private static ILoggerRepository _loggerRepository;

        private static ILoggerRepository LoggerRepository
        {
            get
            {
                if (_loggerRepository != null)
                {
                    return _loggerRepository;
                }
                _loggerRepository = LogManager.CreateRepository(nameof(NullLogManager));
                XmlConfigurator.ConfigureAndWatch(_loggerRepository, new FileInfo("log4net.config"));
                return _loggerRepository;
            }
        }

        public static ILog GetMyLog<T>(T t)
        {
            return LogManager.GetLogger(LoggerRepository.Name, t.GetType());
        }

        public static ILog GetMyLog(object obj)
        {
            return LogManager.GetLogger(LoggerRepository.Name, obj.GetType());
        }

        public static ILog GetMyLog(Type type)
        {
            return LogManager.GetLogger(LoggerRepository.Name, type);
        }

        public static ILog GetMyLog()
        {
            return LogManager.GetLogger(LoggerRepository.Name, nameof(GetMyLog));
        }
    }

调用代码可再次精简

        static void TestNullLogManager()
        {
            var log = MyLogManager.NullLogManager.GetMyLog(typeof(Program));

            const int numberOfCycles = 20000;

            var sw = Stopwatch.StartNew();
            for (var i = 0; i < numberOfCycles; i++)
            {
                log.InfoFormat("testNum: {0} ", i);
            }
            sw.Stop();

            Console.WriteLine();
            Console.WriteLine("Ellapsed: {0}, numPerSec: {1}", sw.ElapsedMilliseconds, numberOfCycles / (sw.ElapsedMilliseconds / (double)1000));
            Console.ReadKey();
        }