.Net Core 使用Nlog 记录日志

一、使用Nlog将日志记录到TXT文本中

参考：https://www.cnblogs.com/qmhuang/p/8305915.html

• 1、安装两个Nugget包：NLog和NLog.Web.AspNetCore
  如下图：
  

  Nlog安装后的效果

• 2、新建Nlog配置文件Nlog.Config，将如下内容放在文件里

  <?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="Warn"
        internalLogFile="internal-nlog.txt">
    <!--define various log targets-->
    <targets>
      <!--write logs to file-->
      <target xsi:type="File" name="allfile" fileName="logs/all/nlog-all-${shortdate}.log"
              layout="${longdate}|${logger}|${uppercase:${level}}|${message} ${exception}" />
  
      <target xsi:type="File" name="ownFile-web" fileName="logs/my/nlog-my-${shortdate}.log"
              layout="${longdate}|${logger}|${uppercase:${level}}|${message} ${exception}" />
      <target xsi:type="Null" name="blackhole" />
    </targets>
    <rules>
      <!--All logs, including from Microsoft-->
      <logger name="*" minlevel="Trace" 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" />
    </rules>
  </nlog>
  

• 3、修改Startup，注入Nlog和引入Nlog.Config

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
    {
        //使用NLog作为日志记录工具
        loggerFactory.AddNLog();
        //引入Nlog配置文件
        env.ConfigureNLog("nlog.config");
  
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }
        else
        {
            app.UseHsts();
        }
  
        app.UseHttpsRedirection();
        app.UseMvc();
    }
  

• 效果如下图：

  
  新增高亮部分的代码

• 4、在接口中依赖Nlog，记录日志

    private ILogger<ValuesController> logger;
    //依赖Nlog
    public ValuesController(ILogger<ValuesController> _logger)
    {
        logger = _logger;
    }
  
  
    // GET api/values
    [HttpGet]
    public ActionResult<IEnumerable<string>> Get()
    {
        logger.LogError("自定义记录日志");//使用Nlog记录
  
        return new string[] { "value1", "value2" };
    }
  

使用说明

二、使用Nlog将日志记录到sql server数据库

• 1、安装Nugget包：NLog.Web.AspNetCore
  效果如下：
  

  图片.png

• 2、新建Nlog配置文件Nlog.Config，将如下内容放在文件里

新建完Nlog文件，配置其属性

        <?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="error">
            <connectionString>${var:connectionString}</connectionString>
            <commandText>
              INSERT INTO [dbo].[Error]
              ([Application]
              ,[Level]
              ,[Logger]
              ,[Callsite]
              ,[RequestHeaders]
              ,[RequestBody]
              ,[RequestURL]
              ,[Response]
              ,[Referrerurl]
              ,[Action]
              ,[Message]
              ,[Exception]
              ,[Operatingtime]
              ,[ServerAddress]
              ,[RemoteAddress])
              VALUES
              (@application
              ,@levels
              ,@logger
              ,@callSite
              ,@requestHeaders
              ,@requestBody
              ,@requestURL
              ,@response
              ,@referrerurl
              ,@action
              ,@message
              ,@exception
              ,@operatingtime
              ,@serverAddress
              ,@remoteAddress);
            </commandText>
            <parameter name="@application" layout="BackendAPI" />
            <parameter name="@levels" layout="${level}" />
            <parameter name="@logger" layout="${logger}" />
            <parameter name="@callSite" layout="${callsite}" />
            <parameter name="@requestHeaders" layout="Null" />
            <parameter name="@requestBody" layout="${event-context:item=requestBody}" />
            <parameter name="@requesturl" layout="${aspnet-request-url}" />
            <parameter name="@response" layout="${event-context:item=response}" />
            <parameter name="@referrerurl" layout="${aspnet-request}" />
            <parameter name="@action" layout="${aspnet-mvc-action}" />
            <parameter name="@message" layout="${event-context:item=message}" />
            <parameter name="@exception" layout="${event-context:item=exception}" />
            <!--<parameter name="@exception" layout="${exception:tostring}" />-->
            <parameter name="@operatingTime" layout="${date}" />
            <parameter name="@serverAddress" layout="${machinename}" />
            <parameter name="@remoteAddress" layout="${aspnet-Request-IP}" />
          </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="Error" writeTo="error" />


        </rules>
      </nlog>

• 3、全局配置Nlog

• 在Startup文件中添加配置

        NLog.LogManager.LoadConfiguration("Nlog.Config").GetCurrentClassLogger();
        NLog.LogManager.Configuration.Variables["connectionString"] = Configuration.GetConnectionString("Test");
  

• 在Program文件中使用Nlog

  .UseNLog();
  

全部配置如下图：

全局配置Nlog

appsettings.json文件内容如下：

  {
    "ConnectionStrings": {
      "Test": "Server=.; Initial Catalog=TestDB; Persist Security Info=True; User ID=**; Password=***;"
    },
    "Logging": {
      "LogLevel": {
        "Default": "Warning"
      }
    },
    "AllowedHosts": "*"
  }

• 4、使用方法

方法一：

private readonly Logger _logger = LogManager.GetCurrentClassLogger();
var logEventInfo = new LogEventInfo() { };
        logEventInfo.Properties["requestBody"] = "requestBody";
        logEventInfo.Properties["exception"] = "exception";
        logEventInfo.Properties["message"] = "context.Exception.Message";
        logEventInfo.Properties["response"] = "response.ToJSON()";

        _logger.Log(LogLevel.Error, logEventInfo);

方法二：

        NLog.Logger logger = LogManager.GetCurrentClassLogger();

        var logEventInfo = new LogEventInfo() { };
        logEventInfo.Properties["requestBody"] = "requestBody";
        logEventInfo.Properties["exception"] = "exception";
        logEventInfo.Properties["message"] = "context.Exception.Message";
        logEventInfo.Properties["response"] = "response.ToJSON()";

        //_logger.Log(LogLevel.Error, logEventInfo);
         logger.Log(LogLevel.Error, logEventInfo);

三、其他

• 网络参考资料
  1、Nlog 在.net core中 记录请求上下文的标识符
• 官方参考资料
  https://github.com/nlog/NLog/wiki/Layout%20Renderers
  https://github.com/nlog/NLog/wiki/Targets
  https://github.com/NLog/NLog/releases/
  http://nlog-project.org/

LogCritical，用来记录严重的事情
LogDebug，记录调试信息
LogError，记录异常
LogInformation，记录信息性的事情
LogTrace，记录追踪信息
LogWarning，记录警告信息

下面是ASP.NET Core里面定义的LogLevel(它是个枚举), 按严重性从低到高排序的:

Trace = 0, 它可以包含敏感拘束, 默认在生产环境中它是被禁用掉的.

Debug = 1, 也是在调试使用, 应该在生产环境中禁用, 但是遇到问题需要调试可以临时启用.

Information = 2, 用来追踪应用程序的总体流程.

Warning = 3, 通常用于记录非正常或意外的事件, 也可以包括不会导致应用程序停止的错误和其他事件, 例如验证错误等.

Error = 4, 用于记录无法处理的错误和异常, 这些信息意味着当前的活动或操作发生了错误, 但不是应用程序级别的错误.

Critical = 5, 用于记录需要立即处理的事件, 例如数据丢失或磁盘空间不足.

None = 6, 如果你不想输出日志, 你可以把程序的最低日志级别设置为None, 此外还可以用来过滤日志.

非常有用的学习例子：https://www.cnblogs.com/bijinshan/p/9140111.html