.NET Core中使用NLog按等级过滤写入控制台、文件、数据库记录日志

<?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" throwExceptions="false" internalLogLevel="Off" internalLogFile="NlogRecords.log">
  <!--Nlog内部日志记录为Off关闭。除非纠错，不可以设为Trace否则速度很慢，起码Debug以上-->
  <extensions>
    <add assembly="NLog.Web.AspNetCore" />
  </extensions>
  <targets>
    <!--通过数据库记录日志 配置
    dbProvider请选择mysql或是sqlserver，同时注意连接字符串,需要安装对应的sql数据提供程序
    MYSQL:
    dbProvider="MySql.Data.MySqlClient.MySqlConnection, MySql.Data"
    connectionString="server=localhost;database=BaseMIS;user=root;password=123456"
    MSSQL:
    dbProvider="Microsoft.Data.SqlClient.SqlConnection, Microsoft.Data.SqlClient"
    connectionString="Server=127.0.0.1;Database=BaseMIS;User ID=sa;Password=123456"
    -->
    <target name="log_database" xsi:type="Database" dbProvider="MySql.Data.MySqlClient.MySqlConnection, MySql.Data" connectionString="server=localhost;port=3306;User Id=root;password=wuzhd123456!;Database=testnlog;pooling=true;character set=utf8;Connection Timeout=160">
      <commandText>
        INSERT INTO TblLogrecords 
        (LogDate,LogLevel,LogType,Logger,Message,MachineName,MachineIp,NetRequestMethod
        ,NetRequestUrl,NetUserIsauthenticated,NetUserAuthtype,NetUserIdentity,Exception)
        VALUES
        (@LogDate,@LogLevel,@LogType,@Logger,@Message,@MachineName,@MachineIp,@NetRequestMethod
        ,@NetRequestUrl,@NetUserIsauthenticated,@NetUserAuthtype,@NetUserIdentity,@Exception);
      </commandText>
      <parameter name="@LogDate" layout="${date}" />
      <parameter name="@LogLevel" layout="${level}" />
      <parameter name="@LogType" layout="${event-properties:item=LogType}" />
      <parameter name="@Logger" layout="${logger}" />
      <parameter name="@Message" layout="${message}" />
      <parameter name="@MachineName" layout="${machinename}" />
      <parameter name="@MachineIp" layout="${aspnet-request-ip}" />
      <parameter name="@NetRequestMethod" layout="${aspnet-request-method}" />
      <parameter name="@NetRequestUrl" layout="${aspnet-request-url}" />
      <parameter name="@NetUserIsauthenticated" layout="${aspnet-user-isauthenticated}" />
      <parameter name="@NetUserAuthtype" layout="${aspnet-user-authtype}" />
      <parameter name="@NetUserIdentity" layout="${aspnet-user-identity}" />
      <parameter name="@Exception" layout="${exception:tostring}" />
    </target>
    <target name="log_file" xsi:type="File" fileName="${basedir}/logs/${shortdate}.log" layout="${longdate} | ${level:uppercase=false} | ${message} ${onexception:${exception:format=tostring} ${newline} ${stacktrace} ${newline}" />
    <!--ColoredConsole彩色控制台 xsi:type="Console"是指定输出到普通控制台-->
    <target name="log_console" xsi:type="ColoredConsole" useDefaultRowHighlightingRules="true" layout="${longdate}|${level}|${logger}|${message} ${exception}">
      <highlight-row condition="level == LogLevel.Trace" foregroundColor="DarkGray" />
      <highlight-row condition="level == LogLevel.Debug" foregroundColor="Gray" />
      <highlight-row condition="level == LogLevel.Info" foregroundColor="White" />
      <highlight-row condition="level == LogLevel.Warn" foregroundColor="Yellow" />
      <highlight-row condition="level == LogLevel.Error" foregroundColor="Red" />
      <highlight-row condition="level == LogLevel.Fatal" foregroundColor="Magenta" backgroundColor="White" />
    </target>
  </targets>
  <rules>
    <!--跳过所有级别的Microsoft组件的日志记录-->
    <!--<logger name="Microsoft.*" maxlevel="Info" final="true" />-->
    <!-- BlackHole without writeTo -->
    <!--只通过数据库记录日志，这里的*，如果给了name名字，代码里用日志记录的时候，取logger需要把name当做参数-->
    <logger name="*" minlevel="Info" writeTo="log_database" />
    <logger name="*" minlevel="Trace" writeTo="log_console" />
    <logger name="*" minlevel="Warn" writeTo="log_file" />
  </rules>
</nlog>

.ConfigureLogging(logging =>
                {
                    logging.ClearProviders();
                    logging.SetMinimumLevel(Microsoft.Extensions.Logging.LogLevel.Trace);
                }).UseNLog();  // NLog: 依赖注入Nlog;

var host = CreateWebHostBuilder(args).Build();
            Logger logger = LogManager.GetCurrentClassLogger();
            try
            {
                logger.Trace("网站启动中...");
                using (IServiceScope scope = host.Services.CreateScope())
                {
                    IConfiguration configuration = scope.ServiceProvider.GetRequiredService<IConfiguration>();
                    //获取到appsettings.json中的连接字符串
                    string sqlString = configuration.GetSection("Connection:MySql").Value;
                    //确保NLog.config中连接字符串与appsettings.json中同步
                    NLogUtil.EnsureNlogConfig("NLog.config", sqlString);
                    logger.Trace("初始化数据库");
                    //用于查看彩色控制台样式，以及日志等级过滤
                    logger.Trace("Test For Trace");
                    logger.Debug("Test For Debug");
                    logger.Info("Test For Info");
                    logger.Warn("Test For Warn");
                    logger.Error("Test For Error");
                    logger.Fatal("Test For Fatal");
                }
                //throw new Exception("测试异常");//for test

                //其他项目启动时需要做的事情
                //code
                logger.Trace("网站启动完成");
                host.Run();
            }
            catch (Exception ex)
            {
                logger.Fatal(ex, "网站启动失败");
                throw;
            }

/// <summary>
        /// 确保NLog配置文件sql连接字符串正确
        /// </summary>
        /// <param name="nlogPath"></param>
        /// <param name="sqlConnectionStr"></param>
        public static void EnsureNlogConfig(string nlogPath, string sqlConnectionStr)
        {
            XDocument xd = XDocument.Load(nlogPath);
            if (xd.Root.Elements().FirstOrDefault(a => a.Name.LocalName == "targets")
                is XElement targetsNode && targetsNode != null &&
                targetsNode.Elements().FirstOrDefault(a => a.Name.LocalName == "target" && a.Attribute("name").Value == "log_database")
                is XElement targetNode && targetNode != null)
            {
                if (!targetNode.Attribute("connectionString").Value.Equals(sqlConnectionStr))//不一致则修改
                {
                    //这里暂时没有考虑dbProvider的变动
                    targetNode.Attribute("connectionString").Value = sqlConnectionStr;
                    xd.Save(nlogPath);
                    //编辑后重新载入配置文件（不依靠NLog自己的autoReload，有延迟）
                    LogManager.Configuration = new XmlLoggingConfiguration(nlogPath);
                }
            }
        }