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。

 1 <?xml version="1.0" encoding="utf-8" ?> 2 <nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd" 3  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 4  xsi:schemaLocation="http://www.nlog-project.org/schemas/NLog.xsd NLog.xsd" 5  autoReload="true" 6  throwExceptions="false" 7  internalLogLevel="Warn"  8  internalLogFile="Logs/nlog-internal.log"> 9 10 <!--internalLogLevel="Off"-->11 <!-- optional, add some variables12  https://github.com/nlog/NLog/wiki/Configuration-file#variables13 -->14 <variable name="myvar" value="myvalue"/>15 16 <!--17  See https://github.com/nlog/nlog/wiki/Configuration-file18  for information on customizing logging rules and outputs.19 -->20 <targets>21 22 <!--23  add your targets here24  See https://github.com/nlog/NLog/wiki/Targets for possible targets.25  See https://github.com/nlog/NLog/wiki/Layout-Renderers for the possible layout renderers.26 -->27 28 <!--29  Write events to a file with the date in the filename.30  <target xsi:type="File" name="f" fileName="${basedir}/logs/${shortdate}.log"31  layout="${longdate} ${uppercase:${level}} ${message}" />32 -->33 34 <!-- write logs to file -->35 <target xsi:type="File" name="allfile" fileName="Logs/${date:format=yyyyMM}/nlog-all-${shortdate}.log"36  layout="${longdate}|${event-properties:item=EventId.Id}|${uppercase:${level}}|${logger} ${newline}${message} ${exception} ${newline}" />37 38 <target xsi:type="File" name="ownFile-web" fileName="Logs/${date:format=yyyyMM}/nlog-own-${shortdate}.log"39  layout="${longdate}|${event-properties:item=EventId.Id}|${uppercase:${level}}|${logger} ${newline}${message} ${exception} ${newline} --- |url: ${aspnet-request-url}|action: ${aspnet-mvc-action}" />40 41 <target xsi:type="Null" name="blackhole" />42 43 <target xsi:type="Database" name="database">44 <connectionString>${var:connectionString}</connectionString>45 <commandText>46  insert into syslogs (Application,Levels,Operatingtime,Operatingaddress,Userid,Logger,Callsite,Requesturl,Referrerurl,Action,Message,Exception)47  values (@application,@levels,@operatingtime,@operatingaddress,@userid,@logger,@callSite,@requesturl,@referrerurl,@action,@message,@exception);48 </commandText>49 <parameter name="@application" layout="WebApi" />50 <parameter name="@levels" layout="${level}" />51 <parameter name="@operatingTime" layout="${date}" />52 <parameter name="@operatingaddress" layout="${aspnet-Request-IP}" />53 <parameter name="@userid" layout="1" />54 <parameter name="@logger" layout="${logger}" />55 <parameter name="@callSite" layout="${callsite}" />56 <parameter name="@requesturl" layout="${aspnet-request-url}" />57 <parameter name="@referrerurl" layout="${aspnet-request}" />58 <parameter name="@action" layout="${aspnet-mvc-action}" />59 <parameter name="@message" layout="${message}" />60 <parameter name="@exception" layout="${exception:tostring}" />61 </target>62 63 </targets>64 65 <rules>66 <!-- add your logging rules here -->67 68 <!--69  Write all events with minimal level of Debug (So Debug, Info, Warn, Error and Fatal, but not Trace) to "f"70  <logger name="*" minlevel="Debug" writeTo="f" />71 -->72 73 <!--All logs, including from Microsoft-->74 <!--minlevel 改为Trace 跟踪全部 Error 只捕获异常-->75 <logger name="*" minlevel="Error" writeTo="allfile" />76 77 <!--Skip Microsoft logs and so log only own logs-->78 <logger name="Microsoft.*" minlevel="Trace" writeTo="blackhole" final="true" />79 <logger name="*" minlevel="Trace" writeTo="ownFile-web" />80 <logger name="*" minlevel="Trace" writeTo="database" /> 81 82 </rules>83 </nlog>84 85 86 <!--增加引用87 <PackageReference Include="NLog.Extensions.Logging" Version="1.2.1" />88 <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。

 1 public void Configure(IApplicationBuilder app, IHostingEnvironment env) 2  { 3  4 #region Nlog记日志 5 //将日志记录到数据库 config/NLog.config 6 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 7 #endregion 8  9 if (env.IsDevelopment())10  app.UseDeveloperExceptionPage();11 else12  app.UseHsts();13  app.UseHttpsRedirection();14 15  app.UseMvc();16 }

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", 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 }

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。