.net core 使用 NLog 记录日志

一、先创建 .net core Web 应用程序

二、程序包控制台输入以下命令行以安装 Nuget 包：

install-package Nlog
install-package Nlog.Web.AspNetCore

三、添加配置文件： nlog.config  ,  注意，右键属性中选择 “复制到目录”-》“如果较新则复制”

<?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="nlog-all-${shortdate}.log"
             layout="${longdate}|${logger}|${uppercase:${level}}|${message} ${exception}" />-->

    <target xsi:type="File" name="ownFile-web" fileName="LogFiles/${shortdate}.log"
             layout="${longdate}|${logger}|${uppercase:${level}}|${message} ${exception}" />
    <!--<target xsi:type="Null" name="blackhole" />-->
  </targets>
  <rules>
    <!--All logs, including from Microsoft-->
    <!-- 记录微软所有日志，一般不开 -->
    <!--<logger name="*" minlevel="Trace" writeTo="allfile" />-->

    <!--Skip Microsoft logs and so log only own logs-->
    <!--<logger name="Microsoft.*" minlevel="Fatal" writeTo="blackhole" final="true" />-->
    <logger name="*" minlevel="Critical" writeTo="ownFile-web" />
  </rules>
</nlog>

四、修改 Startup.cs ,  其实除了引用之外， 也就是加两行代码而已:

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using NLog.Extensions.Logging;
using NLog.Web;

namespace WebApplication1
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.Configure<CookiePolicyOptions>(options =>
            {
                // This lambda determines whether user consent for non-essential cookies is needed for a given request.
                options.CheckConsentNeeded = context => true;
                options.MinimumSameSitePolicy = SameSiteMode.None;
            });


            services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
        }

        // 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)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseCookiePolicy();

            //使用NLog作为日志记录工具
            loggerFactory.AddNLog();
            //引入Nlog配置文件
            env.ConfigureNLog("nlog.config");

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }
    }
}

五、修改 Controller, 输出日志：

        private ILogger<HomeController> logger;

        public HomeController(ILogger<HomeController> _logger)
        {
            logger = _logger;
        }

        public IActionResult Index()
        {
            logger.LogInformation("普通信息日志-----------");
            logger.LogDebug("调试日志-----------");
            logger.LogError("错误日志-----------");
            logger.LogCritical("异常日志-----------");
            logger.LogWarning("警告日志-----------");
            logger.LogTrace("跟踪日志-----------");
            logger.Log(LogLevel.Warning, "Log日志------------------");
            return View();
        }

日志级别：Trace -》Debug-》 Information -》Warning-》 Error-》 Critical

日志级别由小到大， Trace 就包含了所有日志。

如果想修改日志的输出级别，应该在 nlog.config 中修改 minlevel="Trace"

试了一下， Critical 与 Fatal 的输出是一致的。

使用说明： https://github.com/NLog/NLog.Web/wiki/Getting-started-with-ASP.NET-Core-2

详细的配置参考: https://github.com/NLog/NLog/wiki/Configuration-file

中文配置文章： http://www.cnblogs.com/fuchongjundream/p/3936431.html

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