Log4net 的 ASP.NET Core 扩展库

给大家安利一款

log4net

的 ASP.NET Core 扩展库，它是基于

log4net

开发的。 简单易用，开源免费，使用ASP.NET Core自身提供的DI容器来实现服务的注册和消费。直接在程序启动时注册到服务中即可完成全部配置，对于小白用户也可快速上手 log4net 日志组件。

Lightweight Logging Extension implementation of log4net.

Install Package

https://www.nuget.org/packages/Log4net.Extension.AspNetCore

Configure

• Add the

  AddLog4Net()

  call into your

  Configure

  method of the

  Startup

  class.

using Microsoft.Extensions.Logging;

public class Startup
{
//...

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
//...

loggerFactory.AddLog4Net();

//...
}
}

• Add a

  log4net.config

  file with the content:

<?xml version="1.0" encoding="utf-8"?>
<configuration>
<!-- This section contains the log4net configuration settings -->
<log4net>
<appender name="DebugAppender" type="log4net.Appender.ConsoleAppender,log4net">
<layout type="log4net.Layout.PatternLayout,log4net">
<param name="ConversionPattern" value="%d [%t] %-5p %c - %m%n" />
</layout>
</appender>
<appender name="InfoAppender" type="log4net.Appender.RollingFileAppender,log4net">
<param name="File" value="Logs/" />
<param name="AppendToFile" value="true" />
<param name="RollingStyle" value="Date" />
<param name="DatePattern" value="&quot;Logs_&quot;yyyyMMdd&quot;_All.txt&quot;" />
<param name="StaticLogFileName" value="false" />
<layout type="log4net.Layout.PatternLayout,log4net">
<param name="ConversionPattern" value="%d [%t] %-5p %c - %m%n" />
</layout>
</appender>
<appender name="ErrorAppender" type="log4net.Appender.RollingFileAppender,log4net">
<param name="File" value="Logs/" />
<param name="AppendToFile" value="true" />
<param name="RollingStyle" value="Date" />
<param name="DatePattern" value="&quot;Logs_&quot;yyyyMMdd&quot;.txt&quot;" />
<param name="StaticLogFileName" value="false" />
<layout type="log4net.Layout.PatternLayout,log4net">
<param name="ConversionPattern" value="%d [%t] %-5p %c - %m%n" />
</layout>
<filter type="log4net.Filter.LevelRangeFilter">
<levelMin value="ERROR" />
<levelMax value="FATAL" />
</filter>
</appender>
<root>
<level value="ALL" />
<appender-ref ref="ErrorAppender" />
<appender-ref ref="InfoAppender" />
</root>
<logger name="WebLogger">
<appender-ref ref="ErrorAppender" />
</logger>
</log4net>
</configuration>

• Add a global ExceptionFilter:

public void ConfigureServices(IServiceCollection services)
{
//...

services.AddControllers(options =>
{
options.Filters.Add<ExceptionFilter>();
});

//...
}

• appsettings.json

{
"Logging": {
"LogLevel": {
"Default": "Debug",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
}
},
"AllowedHosts": "*"
}

• appsettings.Development.json

{
"Logging": {
"LogLevel": {
"Default": "Information",
"Microsoft": "Warning",
"Microsoft.Hosting.Lifetime": "Information"
}
}
}

• Add the log directory as static, so we can view the logs online.

using Microsoft.Extensions.Logging;

public class Startup
{
//...

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
//...

loggerFactory.AddLog4Net();

//...

app.UseFileServer(new FileServerOptions()
{
FileProvider = new PhysicalFileProvider(Path.Combine(Directory.GetCurrentDirectory(), @"Logs")),
RequestPath = new PathString("/Log"),
EnableDirectoryBrowsing = true
});

//...
}
}

Global Exception Filter

public class ExceptionFilter : IExceptionFilter
{
private readonly ILogger<ExceptionFilter> _logger;
public ExceptionFilter(ILogger<ExceptionFilter> logger)
{
_logger = logger;
}

public void OnException(ExceptionContext filterContext)
{
var log = new StringBuilder();

//log the url
if (filterContext.HttpContext.Request.GetDisplayUrl() != null)
log.AppendLine(filterContext.HttpContext.Request.GetDisplayUrl());

log.AppendLine($"\tIP: {filterContext.HttpContext.Connection.RemoteIpAddress}");

foreach (var key in filterContext.HttpContext.Request.Headers.Keys)
{
log.AppendLine($"\t{key}: {filterContext.HttpContext.Request.Headers[key]}");
}

var exception = filterContext.Exception;
log.AppendLine("\tError Message:" + exception.Message);
if (exception.InnerException != null)
{
PrintInnerException(exception.InnerException, log);
}
log.AppendLine("\tError HelpLink:" + exception.HelpLink);
log.AppendLine("\tError StackTrace:" + exception.StackTrace);

_logger.LogError(log.ToString());
}

private void PrintInnerException(Exception ex, StringBuilder log)
{
log.AppendLine("\tError InnerMessage:" + ex.Message);
if (ex.InnerException != null)
{
PrintInnerException(ex.InnerException, log);
}
}
}