log4net是.Net下一个非常优秀的开源日志记录组件。log4net记录日志的功能非常强大。它可以将日志分不同的等级,以不同的格式,输出到不同的媒介。本文主要是介绍如何在Visual Studio2019 ,ASP.NET Core中使用log4net快速创建系统日志,如何扩展以输出自定义字段
第一步:NuNet包管理器下载安装log4net和Microsoft.Extensions.Logging.Log4Net.AspNetCore
第二步:
方法一:Program读取log4net的配置文件。
public static IHostBuilder CreateHostBuilder(string[] args) => Host.CreateDefaultBuilder(args) .ConfigureLogging(loggingBuilder=> { //配置log4net配置文件的读取 loggingBuilder.AddLog4Net("CfgFile/log4net.Config"); }) .ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); }); }
配置文件:
<?xml version="1.0" encoding="utf-8"?> <log4net> <!-- Define some output appenders --> <appender name="rollingAppender" type="log4net.Appender.RollingFileAppender"> <file value="Customlog\log.txt" /> <!--追加日志内容--> <appendToFile value="true" /> <!--防止多线程时不能写Log,官方说线程非安全--> <lockingModel type="log4net.Appender.FileAppender+MinimalLock" /> <!--可以为:Once|Size|Date|Composite--> <!--Composite为Size和Date的组合--> <rollingStyle value="Composite" /> <!--当备份文件时,为文件名加的后缀--> <datePattern value="yyyyMMdd.TXT" /> <!--日志最大个数,都是最新的--> <!--rollingStyle节点为Size时,只能有value个日志--> <!--rollingStyle节点为Composite时,每天有value个日志--> <maxSizeRollBackups value="20" /> <!--可用的单位:KB|MB|GB--> <maximumFileSize value="3MB" /> <!--置为true,当前最新日志文件名永远为file节中的名字--> <staticLogFileName value="true" /> <!--输出级别在INFO和ERROR之间的日志--> <filter type="log4net.Filter.LevelRangeFilter"> <param name="LevelMin" value="ALL" /> <param name="LevelMax" value="FATAL" /> </filter> <layout type="log4net.Layout.PatternLayout"> <conversionPattern value="%date [%thread] %-5level %logger - %message%newline"/> </layout> </appender> <root> <priority value="ALL"/> <level value="ALL"/> <appender-ref ref="rollingAppender" /> </root> </log4net>
简单测试:
private readonly ILogger<HomeController> _logger; public HomeController(ILogger<HomeController> logger) { _logger = logger; _logger.LogWarning("HomeController被构造..."); } public IActionResult Index() { _logger.LogInformation("This is HomeController.Index"); base.ViewBag.User1 = "张三"; base.ViewData["User2"] = "李四"; base.TempData["User3"] = "王五"; object user4 = "赵六"; if (HttpContext.Session.GetString("User5") == null) { HttpContext.Session.SetString("User5", "田七"); } return View(); }
查看日志文件:
方法二:Startup程序启动时候配置文件读取(日志工厂)
public void Configure(IApplicationBuilder app, IWebHostEnvironment env,ILoggerFactory loggerFactory) { if (env.IsDevelopment()) { app.UseDeveloperExceptionPage(); } else { app.UseExceptionHandler("/Home/Error"); } loggerFactory.AddLog4Net("CfgFile/log4net.Config"); app.UseSession(); app.UseStaticFiles(); app.UseRouting(); app.UseAuthorization(); app.UseEndpoints(endpoints => { endpoints.MapControllerRoute( name: "default", pattern: "{controller=Home}/{action=Index}/{id?}"); }); }
测试结果: