本文转载自微信公众号「后端Q」，篇关作者conan。篇关转载本文请联系后端Q公众号。篇关
1、篇关创建一个新的篇关ASP.NET Core项目
在Visual Studio 2019中。需要版本16.8+
2、篇关手动或使用NuGet在csproj中添加依赖项
安装最新版本：
NLog.Web.AspNetCore 4.9+ 如有可能，篇关更新NLog软件包 在csproj中：
<ItemGroup> <PackageReference Include="NLog.Web.AspNetCore" Version="4.9.3" /> <PackageReference Include="NLog" Version="4.7.6" /> </ItemGroup> 3、篇关创建一个nlog.config文件。篇关
在项目的篇关根目录中创建nlog.config(全部小写)文件。云服务器
我们使用以下示例：
<?篇关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="Info" internalLogFile="c:\temp\internal-nlog.txt"> <!-- enable asp.net core layout renderers --> <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}|${ event-properties:item=EventId_Id}|${ uppercase:${ level}}|${ logger}|${ message} ${ exception:format=tostring}" /> <!-- another file log, only own logs. Uses some ASP.NET core renderers --> <target xsi:type="File" name="ownFile-web" fileName="c:\temp\nlog-own-${ shortdate}.log" layout="${ longdate}|${ event-properties:item=EventId_Id}|${ uppercase:${ level}}|${ logger}|${ message} ${ exception:format=tostring}|url: ${ aspnet-request-url}|action: ${ aspnet-mvc-action}" /> </targets> <!-- rules to map from logger name to target --> <rules> <!--All logs, including from Microsoft--> <logger name="*" minlevel="Trace" writeTo="allfile" /> <!--Skip non-critical Microsoft logs and so log only own logs--> <logger name="Microsoft.*" maxlevel="Info" final="true" /> <!-- BlackHole without writeTo --> <logger name="System.Net.Http.*" maxlevel="Info" final="true" /> <!-- BlackHole without writeTo --> <logger name="*" minlevel="Trace" writeTo="ownFile-web" /> </rules> </nlog> 请注意，如果删除所有其他LoggingProviders(如控制台)并且仅使用NLog，篇关则可能必须特别注意Hosting Lifetime Startup Messages。篇关因为这可能导致托管环境(Visual Studio / Docker / Azure容器)看不到已启动的篇关应用程序。
4、篇关更新program.cs
更新program.cs
using Microsoft.AspNetCore.Hosting; using Microsoft.Extensions.Hosting; using Microsoft.Extensions.Logging; using System; using NLog.Web; namespace ASP.NET_Core_5_NLog_Example { public class Program { public static void Main(string[] args) { var logger = NLogBuilder.ConfigureNLog("nlog.config").GetCurrentClassLogger(); try { logger.Debug("init main"); CreateHostBuilder(args).Build().Run(); } catch (Exception exception) { //NLog: catch setup errors logger.Error(exception, "Stopped program because of exception"); throw; } finally { // Ensure to flush and stop internal timers/threads before application-exit (Avoid segmentation fault on Linux) NLog.LogManager.Shutdown(); } } public static IHostBuilder CreateHostBuilder(string[] args) => Host.CreateDefaultBuilder(args) .ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); }) .ConfigureLogging(logging => { logging.ClearProviders(); logging.SetMinimumLevel(LogLevel.Trace); }) .UseNLog(); // NLog: Setup NLog for Dependency injection } } 5、配置appsettings.json / appsettings.Development.json
中指定的日志记录配置appsettings.json会覆盖对的任何调用SetMinimumLevel。因此"Default":，高防服务器请根据您的需要删除或正确调整它。
{ "Logging": { "IncludeScopes": false, "LogLevel": { "Default": "Trace", "Microsoft": "Warning", "Microsoft.Hosting.Lifetime": "Information" } }, "AllowedHosts": "*" } 切记还要更新任何特定于环境的配置，以免引起任何意外。前任appsettings.Development.json
6、写日志
将ILogger注入您的控制器中：
using Microsoft.Extensions.Logging; public class HomeController : Controller { private readonly ILogger<HomeController> _logger; public HomeController(ILogger<HomeController> logger) { _logger = logger; _logger.LogDebug(1, "NLog injected into HomeController"); } public IActionResult Index() { _logger.LogInformation("Hello, this is the index!"); return View(); } 7、示例输出
启动ASP.NET Core网站时，我们得到两个文件：
2020-12-29 16:47:02.5291||DEBUG|ASP.NET_Core_5_NLog_Example.Program|init main |url: |action: 2020-12-29 16:47:03.5943|1|DEBUG|ASP.NET_Core_5_NLog_Example.Controllers.HomeController|NLog injected into HomeController |url: https://localhost/|action: Index 2020-12-29 16:47:03.5943||INFO|ASP.NET_Core_5_NLog_Example.Controllers.HomeController|Hello, this is the index! |url: https://localhost/|action: Index 2020-12-29 16:47:02.5291||DEBUG|ASP.NET_Core_5_NLog_Example.Program|init main 2020-12-29 16:47:03.5260||INFO|Microsoft.Hosting.Lifetime|Application started. Press Ctrl+C to shut down. 2020-12-29 16:47:03.5260||INFO|Microsoft.Hosting.Lifetime|Hosting environment: Development 2020-12-29 16:47:03.5260||INFO|Microsoft.Hosting.Lifetime|Content root path: D:\nlog\NLog.Web\examples\ASP.NET Core 5\ASP.NET Core 5 NLog Example 2020-12-29 16:47:03.5943|1|DEBUG|ASP.NET_Core_5_NLog_Example.Controllers.HomeController|NLog injected into HomeController 2020-12-29 16:47:03.5943||INFO|ASP.NET_Core_5_NLog_Example.Controllers.HomeController|Hello, this is the index!