.Net Core 使用NLog记录日志到文件和数据库的操作方法_ASP.NET教程

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" />-->

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": "*"
}

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
  }
}

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();
       }

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", 1);
          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
      }

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。

.Net Core 使用NLog记录日志到文件和数据库的操作方法