和之前的ASP.NET MVC中的使用LOG4NET的方法有些不同，这里先记录一下，使用步骤如下 ：

1. 建立 ASP.NET CORE项目中，NUGET中搜索log4net后下载安装

2. 根目录建立 log4net.config文件，内容如下：

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

<configuration>

  <!-- This section contains the log4net configuration settings -->

  <log4net>

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

      <layout type="log4net.Layout.PatternLayout" value="%date [%thread] %-5level %logger - %message%newline" />

    </appender>

    <!--<appender name="FileAppender" type="log4net.Appender.FileAppender">

      <file value="log-file.log" />

      <appendToFile value="true" />

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

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

      </layout>

    </appender>-->

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

      <file value="logfile/" />

      <appendToFile value="true" />

      <rollingStyle value="Composite" />

      <staticLogFileName value="false" />

      <datePattern value="yyyyMMdd'.log'" />

      <maxSizeRollBackups value="10" />

      <maximumFileSize value="1MB" />

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

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

      </layout>

    </appender>

    <!-- Setup the root category, add the appenders and set the default level -->

    <root>

      <level value="ALL" />

      <appender-ref ref="ConsoleAppender" />

      <appender-ref ref="FileAppender" />

      <appender-ref ref="RollingLogFileAppender" />

    </root>

  </log4net>

</configuration>

3. Startup.cs文件中的Startup方法和ConfigureServices方法里的AddMvc代码改下，核心代码如下，记得引用相应的命名空间：

        //log4net日志

        public static ILoggerRepository repository { get; set; }

        public Startup(IConfiguration configuration)

        {

            Configuration = configuration;

            //加载log4net日志配置文件

            repository = LogManager.CreateRepository("NETCoreRepository");

            XmlConfigurator.Configure(repository, new FileInfo("log4net.config"));

        }

        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(options =>

            {

                options.Filters.Add<Models.HttpGlobalExceptionFilter>(); //加入全局异常类

            });

        }

4. Models文件夹中建立 HttpGlobalExceptionFilter.cs 类，用于全局异常后记录到日志中，内容代码如下 ：

using log4net;

using Microsoft.AspNetCore.Mvc.Filters;

using System;

using System.Collections.Generic;

using System.Linq;

using System.Threading.Tasks;

namespace WebApplication1.Models

{

    /// <summary>

    /// 全局异常类

    /// </summary>

    public class HttpGlobalExceptionFilter : IExceptionFilter

    {

        private ILog log = LogManager.GetLogger(Startup.repository.Name, typeof(HttpGlobalExceptionFilter));

        public void OnException(ExceptionContext context)

        {

            log.Error(context.Exception);

        }

    }

}

5. 下面是控制器的代码，有异常会自动记录下来，用那个log也能手工记录日志信息

using System;

using System.Collections.Generic;

using System.Diagnostics;

using System.Linq;

using System.Threading.Tasks;

using log4net;

using Microsoft.AspNetCore.Mvc;

using WebApplication1.Models;

namespace WebApplication1.Controllers

{

    public class HomeController : Controller

    {

        private ILog log = LogManager.GetLogger(Startup.repository.Name, typeof(HttpGlobalExceptionFilter));

        public IActionResult Index()

        {

            throw new Exception("牛腩自定义异常！！！");  //有异常则会记录到logfile文件夹中

            return View();

        }

        public IActionResult About()

        {

            ViewData["Message"] = "Your application description page.";

            log.Info("打开about页面了！！！"); //普通的记录日志

            return View();

        }

 

    }

}