.Net Core 使用NLog记录日志到文件和数据库

NLog 记录日志是微软官方推荐使用。

接下来，通过配置日志记录到文件和Sql Server数据库。

第一步：首先添加包NLog.Config （可通过微软添加包命令Install-Package 包名进行添加，也可以通过管理NuGet程序包进行添加），添加成功后会生成NLog.config配置文件。并对该配置文件进行配置。详细配置可参考Git上 NLog说明。

一下是我个人配置。

 <?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"
       xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd"
       autoReload="true"
       throwExceptions="false"
       internalLogLevel="Warn"
       internalLogFile="Logs/nlog-internal.log">

   <!--internalLogLevel="Off"-->
   <!-- optional, add some variables
   https://github.com/nlog/NLog/wiki/Configuration-file#variables
   -->
   <variable name="myvar" value="myvalue"/>

   <!--
   See https://github.com/nlog/nlog/wiki/Configuration-file
   for information on customizing logging rules and outputs.
    -->
   <targets>

     <!--
     add your targets here
     See https://github.com/nlog/NLog/wiki/Targets for possible targets.
     See https://github.com/nlog/NLog/wiki/Layout-Renderers for the possible layout renderers.
     -->

     <!--
     Write events to a file with the date in the filename.
     <target xsi:type="File" name="f" fileName="${basedir}/logs/${shortdate}.log"
             layout="${longdate} ${uppercase:${level}} ${message}" />
     -->

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

     <target xsi:type="File" name="ownFile-web" fileName="Logs/${date:format=yyyyMM}/nlog-own-${shortdate}.log"
              layout="${longdate}|${event-properties:item=EventId.Id}|${uppercase:${level}}|${logger} ${newline}${message} ${exception} ${newline} --- |url: ${aspnet-request-url}|action: ${aspnet-mvc-action}" />

     <target xsi:type="Null" name="blackhole" />

     <target xsi:type="Database" name="database">
       <connectionString>${var:connectionString}</connectionString>
       <commandText>
         insert into syslogs (Application,Levels,Operatingtime,Operatingaddress,Userid,Logger,Callsite,Requesturl,Referrerurl,Action,Message,Exception)
         values (@application,@levels,@operatingtime,@operatingaddress,@userid,@logger,@callSite,@requesturl,@referrerurl,@action,@message,@exception);
       </commandText>
       <parameter name="@application" layout="WebApi" />
       <parameter name="@levels" layout="${level}" />
       <parameter name="@operatingTime" layout="${date}" />
       <parameter name="@operatingaddress" layout="${aspnet-Request-IP}" />
       <parameter name="@userid" layout="1" />
       <parameter name="@logger" layout="${logger}" />
       <parameter name="@callSite" layout="${callsite}" />
       <parameter name="@requesturl" layout="${aspnet-request-url}" />
       <parameter name="@referrerurl" layout="${aspnet-request}" />
       <parameter name="@action" layout="${aspnet-mvc-action}" />
       <parameter name="@message" layout="${message}" />
       <parameter name="@exception" layout="${exception:tostring}" />
     </target>

   </targets>

   <rules>
     <!-- add your logging rules here -->

     <!--
     Write all events with minimal level of Debug (So Debug, Info, Warn, Error and Fatal, but not Trace)  to "f"
     <logger name="*" minlevel="Debug" writeTo="f" />
     -->

     <!--All logs, including from Microsoft-->
     <!--minlevel 改为Trace 跟踪全部 Error 只捕获异常-->
     <logger name="*" minlevel="Error" 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" />
     <logger name="*" minlevel="Trace" writeTo="database" />    

   </rules>
 </nlog>

 <!--增加引用
 <PackageReference Include="NLog.Extensions.Logging" Version="1.2.1" />
 <PackageReference Include="NLog.Web.AspNetCore" Version="4.6.0" />-->

NLog.config

说明：targets 中有一节点为Database，是配置将日志写入数据库中，注意需要在数据库中添加该记录日志表。

{
  "ConnectionStrings": {
    "DefaultConnection": "Data Source=192.168.30.133;Initial Catalog=Test;User ID=sa;Password=123456;Trusted_Connection=True;MultipleActiveResultSets=true;Integrated Security=false;"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Warning"
    }
  },
  "AllowedHosts": "*"
}

appsettings.json

第二步：添加包NLog.Web.AspNetCore，在Program.cs中的WebHost加入".UseNLog()"（该属于程序集NLog.Web，需要添加引用using NLog.Web;）,即为添加nlog.

using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using NLog.Web;

namespace WebApi
{
    public class Program
    {
        public static void Main(string[] args)
        {
            CreateWebHostBuilder(args).Build().Run();
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .UseNLog(); //加入nlog日志
    }
}

Program.cs

第三步：在Startup.cs中的Configure方法中添加记日志代码，即需要加载的配置文件和配置日志写入数据库连接字符串代码。注意：为避免中文乱码问题需要添加System.Text.Encoding.CodePages包。

  public void Configure(IApplicationBuilder app, IHostingEnvironment env)
         {

             #region Nlog记日志
             //将日志记录到数据库                 config/NLog.config
             NLog.LogManager.LoadConfiguration("nlog.config").GetCurrentClassLogger();       NLog.LogManager.Configuration.Variables["connectionString"] = Configuration.GetConnectionString("DefaultConnection");   Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);  //避免日志中的中文输出乱码
             #endregion

             if (env.IsDevelopment())
                 app.UseDeveloperExceptionPage();
             else
                 app.UseHsts();
   app.UseHttpsRedirection();

             app.UseMvc();
         }

Configure方法

第四步：使用微软推荐的方式在在构造方法中将将日志对象注入。

 public class UsersController : Controller
    {
        /// <summary>
        /// 日志对象
        /// </summary>
        private readonly ILogger logger;
         public UsersController(ILoggerFactory loggerFactory)
        {
            this.logger = loggerFactory.CreateLogger<UsersController>();

            #region 测试日志
            logger.LogTrace("开发阶段调试，可能包含敏感程序数据", );
            logger.LogDebug("开发阶段短期内比较有用，对调试有益。");
            logger.LogInformation("你访问了首页。跟踪程序的一般流程。");
            logger.LogWarning("警告信息！因程序出现故障或其他不会导致程序停止的流程异常或意外事件。");
            logger.LogError("错误信息。因某些故障停止工作");
            logger.LogCritical("程序或系统崩溃、遇到灾难性故障！！！");
            #endregion
        }

构造方法中注入

所有工作完成，运行程序。在配置NLog路径下生成日志文件，同时，在数据库中生成日志。