ASP.NET Core 中的日志记录
https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/logging/?view=aspnetcore-2.1

日志级别：Trace -》Debug-》 Information -》Warning-》 Error-》 Critical
级别包含范围由大到小 ，如 Trace 就包含了所有信息。

基础用法

public class HomeController : Controller ???{ ???????private readonly ILogger _logger; ???????public HomeController(ILogger<HomeController> logger) ???????{ ???????????_logger = logger; ???????} ???????public IActionResult Index() ???????{ ???????????_logger.LogInformation("你访问了首页"); ???????????_logger.LogWarning("警告信息"); ???????????_logger.LogError("错误信息"); ???????????return View(); ???????} ???}

日志事件 ID

 ???public class LoggingEvents ???{ ???????public const int GenerateItems = 1000; ???????public const int ListItems = 1001; ???????public const int GetItem = 1002; ???????public const int InsertItem = 1003; ???????public const int UpdateItem = 1004; ???????public const int DeleteItem = 1005; ???????public const int GetItemNotFound = 4000; ???????public const int UpdateItemNotFound = 4001; ???}

 ???_logger.LogWarning(LoggingEvents.GetItemNotFound, "GetById({ID}) NOT FOUND", 100);

结果：
warn: TodoApi.Controllers.TodoController[4000]
GetById(100) NOT FOUND

NLog 输出到文件

https://github.com/NLog/NLog.web/wiki
asp.net core 2
https://github.com/NLog/NLog.Web/wiki/Getting-started-with-ASP.NET-Core-2

Create a nlog.config file.

<?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="*" minlevel="Trace" writeTo="ownFile-web" /> ?</rules></nlog>

复制到输出目录：始终复制

Update program.cs

这里 nlog-all-.log 是记录所有日志，nlog-own-.log 记录跳过Microsoft 开头的类库输出的相关信息，剩下的信息。

参考：https://www.cnblogs.com/linezero/p/Logging.html

asp.net core 日志

原文地址：https://www.cnblogs.com/tangge/p/10061199.html