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:tempinternal-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:tempnlog-all-${shortdate}.log" layout="${longdate}|${event-properties:item=EventId_Id}|${uppercase:${level}}|${logger}|${message} ${exception:format=tostring}" /> <!-- another file log,only own logs. Uses some ASP.NET core renderers --> <target xsi:type="File" name="ownFile-web" fileName="c:tempnlog-own-${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