asp.net core 虽然自带了日志，但是还是老牌Log4Net日志强大。ASP.NET Core有很好的扩展，可以把Log4net配置为类似为内置日志模块，

利用IOC，很好的在其他组件中使用

1 使用第三方组件 Microsoft.Extensions.Logging.Log4Net.AspNetCore，在nuget中搜索即可

2. 注册

public class Startup

    {

        public static ILoggerRepository repository { get; set; }

        public Startup(IConfiguration configuration)

        {

            Configuration = configuration;

        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.

        public void ConfigureServices(IServiceCollection services)

        {

            services.AddMvc();

        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.

        public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)

        {

            if (env.IsDevelopment())

            {

                app.UseDeveloperExceptionPage();

            }

            loggerFactory.AddLog4Net();

            app.UseMvc();

        }

  3. 使用

 [Route("api/[controller]")]

    public class ValuesController : Controller

    {

        private readonly ILogger log;

        public ValuesController(ILogger<ValuesController> logger)

        {

            this.log = logger;

        }

        // GET api/values

        [HttpGet]

        public IEnumerable<string> Get()

        {

            log.LogInformation("Get values using Log4net ");

            return new string[] { "value1", "value2","value3","value4" };

        }

        // GET api/values/5

        [HttpGet("{id}")]

        public string Get(int id)

        {

            log.LogInformation("Get values by id " + id.ToString() + " using log4net");

            return "value test" +id.ToString();

        }

    }

}

 

配置文件 log4net.config

<?xml version="1.0" encoding="utf-8"?>

<configuration>

  <log4net>

    <root>

      <level value="ALL" />

      <appender-ref ref="RollingFileAppender" />

    </root>

    <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">

      <file value="Logs\log.txt" />

      <appendToFile value="true" />

      <rollingStyle value="Size" />

      <maxSizeRollBackups value="10" />

      <maximumFileSize value="1024KB" />

      <staticLogFileName value="true" />

      <layout type="log4net.Layout.PatternLayout">

        <conversionPattern value="%date [%thread] %-5level %logger [%property{NDC}] - %message%newline" />

      </layout>

    </appender>

  </log4net>

</configuration>

放在发布的根目录下即可。

注意：Microsoft.Extensions.Logging.Log4Net.AspNetCore 默认的配置文件名为log4net.config，并且配置文件的根节点log4net，

查看源码即可看到,上面的配置文件节点是我自己修改过后的，变成 log4netConfig["configuration"]["log4net"];

Microsoft.Extensions.Logging.Log4Net.AspNetCore 部分源码：

        /// <summary>

        /// The default log4net config file name.

        /// </summary>

        private const string DefaultLog4NetConfigFile = "log4net.config";

 

        /// <summary>

        /// Parses log4net config file.

        /// </summary>

        /// <param name="filename">The filename.</param>

        /// <returns>The <see cref="XmlElement"/> with the log4net XML element.</returns>

        private static XmlElement Parselog4NetConfigFile(string filename)

        {

            using (FileStream fp = File.OpenRead(filename))

            {

                var settings = new XmlReaderSettings

                {

                    DtdProcessing = DtdProcessing.Prohibit

                };

              

                var log4netConfig = new XmlDocument();

                log4netConfig.Load(filename);

                using (var reader = XmlReader.Create(fp, settings))

                {

                    log4netConfig.Load(reader);

                }

                fp.Flush();

                fp.Dispose();

                return log4netConfig["log4net"];

            }

        }

 

 较好的做法是利用Common.logging +Log4net，还在实践中...

 在windows 7上正常，未在Linux上验证..

 参考文章：

 http://www.cnblogs.com/linezero/p/log4net.html

 https://dotnetthoughts.net/how-to-use-log4net-with-aspnetcore-for-logging/