asp.net core项目添加NLog

用VS2017新增一个.net core项目。

通过Nuget安装：NLog.Web.AspNetCore

1.在项目中添加 NLog.config文件

2.配置文件中添加如下代码（摘录官方文档）：

<?xml version="1.0" encoding="utf-8" ?>
<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      autoReload="true"
      internalLogLevel="Warn"
      internalLogFile="c:\temp\internal-nlog.txt">

  <!-- Load the ASP.NET Core plugin -->
  <extensions>
    <add assembly="NLog.Web.AspNetCore"/>
  </extensions>

  <!-- the targets to write to -->
  <targets>
     <!-- write logs to file -->
     <target xsi:type="File" name="allfile" fileName="c:\temp\nlog-all-${shortdate}.log"
                 layout="${longdate}|${event-properties:item=EventId.Id}|${logger}|${uppercase:${level}}|${message} ${exception}" />

   <!-- another file log, only own logs. Uses some ASP.NET core renderers -->
     <target xsi:type="File" name="ownFile-web" fileName="c:\temp\nlog-own-${shortdate}.log"
             layout="${longdate}|${event-properties:item=EventId.Id}|${logger}|${uppercase:${level}}|  ${message} ${exception}|url: ${aspnet-request-url}|action: ${aspnet-mvc-action}" />

     <!-- write to the void aka just remove -->
    <target xsi:type="Null" name="blackhole" />
  </targets>

  <!-- rules to map from logger name to target -->
  <rules>
    <!--All logs, including from Microsoft-->
    <logger name="*" minlevel="Trace" writeTo="allfile" />

    <!--Skip Microsoft logs and so log only own logs-->
    <logger name="Microsoft.*" minlevel="Trace" writeTo="blackhole" final="true" />
    <logger name="*" minlevel="Trace" writeTo="ownFile-web" />
  </rules>
</nlog>

在target中：通过filename指定文件的名称（输出路径），layout指定输出的内容格式。

action: ${aspnet-mvc-action}记录action中记录的日志。

在logger中：minlevel指定文件记录的最低级别的日志，workto表明是哪个文件

3.startup.cs文件做如下修改

using NLog.Extensions.Logging;
using NLog.Web;

public Startup(IHostingEnvironment env)
{
    env.ConfigureNLog("nlog.config");
}

public void ConfigureServices(IServiceCollection Services)
{
    //call this in case you need aspnet-user-authtype/aspnet-user-identity
    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
}

// 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)
{

    //add NLog to ASP.NET Core
    loggerFactory.AddNLog();

    //add NLog.Web
    app.AddNLogWeb();
}

4.控制器中添加测试代码

官方文档：

https://github.com/NLog/NLog.Extensions.Logging