如何将 log4net 配置写入 appsettings.json？

Question

我已将 log4net 实施到 .NET core 2.0 中，以登录文本文件。由于 log4net 有一个配置文件，其中包含 XML configuration。所以，我创建了一个单独的文件 log4net.config 来设置它的配置，它工作正常。但是我想把它的配置设置成appsettings.json。是否可以将log4net配置写入appsettings.json.

<appSettings>
    <add key="IsLog" value="True" />
    <add key="MaxThreads" value="3" />
  </appSettings>
  <log4net debug="false">
    <root>
      <level value="ALL" />
      <appender-ref ref="RollingLogFileAppender" />
    </root>
 <appender name="RollingLogFileAppender" type="log4net.Appender.RollingFileAppender">
    <file value="./logs/logfile.txt" />
    <appendToFile value="false" />
    <rollingStyle value="Size" />
    <maxSizeRollBackups value="-1" />
    <maximumFileSize value="50GB" />
    <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
    </layout>
</appender>   
  </log4net>

这是我的 XML 配置。

我找到了这个 question，其中提到 log4net don't support Json projects。能不能把它的配置写成appsettings.json.

Answer 1

也许这不是正确的方法，但无论如何我设法在 appSettings.json 中使用了我的 log4net.config。我把我的答案放在这里，如果他们不想为项目使用额外的配置文件，它可以帮助他们。

所以我所做的就是将 XML 转换为 JSON 并使用 JSON 作为我 appSettings.json 上的字符串，之后我使用以下代码读取字符串。

appSettings.json

{
  "ConnectionStrings": {
    "LoggerConfig": "Config string"
  }
}

Json to XML Conversion using Newtonsoft.Json

 string xmlElement = _configuration["ConnectionStrings:LoggerConfig"];
 XmlDocument doc = (XmlDocument)JsonConvert.DeserializeXmlNode(xmlElement);
 XmlConfigurator.Configure(logRepository, GenerateStreamFromString(doc.InnerXml));

此代码用于将JSON转换为XML但不会提供XML 内容作为 Element 因此，我将其用作流。为了将字符串转换为流，我使用了以下代码。

        public static Stream GenerateStreamFromString(string s)
        {
            var stream = new MemoryStream();
            var writer = new StreamWriter(stream);
            writer.Write(s);
            writer.Flush();
            stream.Position = 0;
            return stream;
        }

而且效果很好。

Here I used to convert first my XML to JSON and again JSON to XML to use it as a log4net config, but if anyone wants then use XML directly as a string, So it will reduce some code.

Answer 2

如果你使用 Microsoft.Extensions.Logging.Log4Net.AspNetCore nuget 包，有一种方法可以在 appsettings.json 中保留 log4net 配置（但老实说不是很有用）。

您可以写入 appsettings.json（或 appsettings.Environment.json 用于不同的环境）规则覆盖来自 log4net 配置文件的节点。

Documentation

从 appsettings.json.

设置日志记录级别的示例

appsettings.json:

{
  "Log4NetCore": {
    "PropertyOverrides": [
      {
        "XPath": "/log4net/root/level",
        "Attributes": {
          //"value": "ALL"
          //"value": "DEBUG"
          //"value": "INFO"
          "value": "WARN"
          //"value": "ERROR"
          //"value": "FATAL"
          //"value": "OFF"
        }
      }
    ]
  }
}

您仍然需要 log4net 配置文件，其中包含您希望从 appsettings.json 覆盖的节点：

<?xml version="1.0" encoding="utf-8" ?>
<log4net>
  <appender name="DebugAppender" type="log4net.Appender.DebugAppender" >
    <layout type="log4net.Layout.PatternLayout">
      <conversionPattern value="%date [%thread] %-5level %logger - %message%newline" />
    </layout>
  </appender>
  <appender name="RollingFile" type="log4net.Appender.RollingFileAppender">
    <file value="example.log" />
     <appendToFile value="true" />
    <maximumFileSize value="100KB" />
    <maxSizeRollBackups value="2" />
    <layout type="log4net.Layout.PatternLayout">
        <conversionPattern value="%date %5level %logger.%method [%line] - MESSAGE: %message%newline %exception" />
    </layout>
  </appender>
  <root>
    <level value="ALL"/>
    <appender-ref ref="DebugAppender" />
    <appender-ref ref="RollingFile" />
  </root>
</log4net>

在Startup.cs注册：

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

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.AddMvc();
    }

    // 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)
    {
        // Add these lines
        var loggingOptions = this.Configuration.GetSection("Log4NetCore")
                                               .Get<Log4NetProviderOptions>();
        loggerFactory.AddLog4Net(loggingOptions);

        app.UseMvc();
    }
}

如何将 log4net 配置写入 appsettings.json？

How to write log4net config into appsettings.json?

log4net

asp.net-core-2.0

log4net-configuration