Log4Net 相信大家都很熟悉了，算是比较主流和著名的日志组件了。
开源地址： https://github.com/apache/logging-log4net
最佳实践
在项目中添加组件包
Install-Package log4net
添加 log4net.config 文件
<?xml version="1.0" encoding="utf-8" ?> <configuration> <configSections> <section type="log4net.Config.Log4NetConfigurationSectionHandler, log4net"/> </configSections> <log4net debug="false"> <appender type="log4net.Appender.RollingFileAppender,log4net"> <param value="log4net/info/" /> <param value="true" /> <param value="-1"/> <param value="5MB"/> <param value="Composite" /> <param value="yyyyMMdd\\HH".log"" /> <param value="false" /> <layout type="log4net.Layout.PatternLayout,log4net"> <param value="%n { "system": "Meowv.Blog", "datetime": "%d", "description": "%m", "level": "%p", "info": "%exception" }" /> </layout> <filter type="log4net.Filter.LevelRangeFilter"> <levelMin value="INFO" /> <levelMax value="INFO" /> </filter> </appender> <appender type="log4net.Appender.RollingFileAppender,log4net"> <param value="log4net/error/" /> <param value="true" /> <param value="-1"/> <param value="5MB"/> <param value="Composite" /> <param value="yyyyMMdd\\HH".log"" /> <param value="false" /> <layout type="log4net.Layout.PatternLayout,log4net"> <param value="%n { "system": "Meowv.Blog", "datetime": "%d", "description": "%m", "level": "%p", "info": "%exception" }" /> </layout> <filter type="log4net.Filter.LevelRangeFilter"> <levelMin value="ERROR" /> <levelMax value="ERROR" /> </filter> </appender> <root> <level value="ALL"></level> <appender-ref ref="info"/> <appender-ref ref="error"/> </root> </log4net> </configuration>
控制台项目
using log4net; using log4net.Config; using System; using System.IO; using System.Reflection; namespace ConsoleAppDemo { class Program { static void Main(string[] args) { var log4netRepository = LogManager.GetRepository(Assembly.GetEntryAssembly()); XmlConfigurator.Configure(log4netRepository, new FileInfo("log4net.config")); ILog log = LogManager.GetLogger(log4netRepository.Name, "NETCorelog4net"); log.Info("NETCorelog4net log"); log.Info("test log"); log.Error("error"); log.Info("linezero"); Console.ReadKey(); } } }
AspNetCore项目
新建一个静态类，写一个扩展方法 UseLog4Net() ，用于 log4net 初始化。
public static class Log4NetExtensions { public static IHostBuilder UseLog4Net(this IHostBuilder hostBuilder) { var log4netRepository = LogManager.GetRepository(Assembly.GetEntryAssembly()); XmlConfigurator.Configure(log4netRepository, new FileInfo("log4net.config")); return hostBuilder; } }
扩展方法返回 IHostBuilder 对象，这样可以链式调用，美化代码，然后在 Program.cs 中使用扩展方法 UseLog4Net() 。
using Microsoft.AspNetCore.Hosting; using Microsoft.Extensions.Hosting; namespace WebAppDemo { public class Program { public static void Main(string[] args) { CreateHostBuilder(args).Build().Run(); } public static IHostBuilder CreateHostBuilder(string[] args) => Host.CreateDefaultBuilder(args) .ConfigureWebHostDefaults(webBuilder => { webBuilder.UseStartup<Startup>(); }).UseLog4Net(); } }
配置完成，然后在任意地方写入日志即可。
using log4net; using Microsoft.AspNetCore.Mvc; using System; using System.Collections.Generic; using System.Linq; namespace WebAppDemo.Controllers { [ApiController] [Route("[controller]")] public class WeatherForecastController : ControllerBase { private static readonly string[] Summaries = new[] { "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching" }; private readonly ILog _log; public WeatherForecastController() { _log = LogManager.GetLogger(typeof(WeatherForecastController)); } [HttpGet] public IEnumerable<WeatherForecast> Get() { _log.Info("Hello, this is a Weather api!"); _log.Warn("Wran !!!"); _log.Error("Controller Error"); var rng = new Random(); return Enumerable.Range(1, 5).Select(index => new WeatherForecast { Date = DateTime.Now.AddDays(index), TemperatureC = rng.Next(-20, 55), Summary = Summaries[rng.Next(Summaries.Length)] }) .ToArray(); } } }
