.NET6在WebApi中使用日志组件log4net

下面是“.NET6在WebApi中使用日志组件log4net”的完整攻略：

1. 安装log4net

在.NET6 WebApi的项目中，可以通过Nuget包管理器安装log4net组件。在Visual Studio中，打开Nuget包管理器，搜索“log4net”，然后安装。

2. 配置log4net

在项目中添加log4net的配置文件（一般为log4net.config）。下面是一个示例的log4net配置文件：

<?xml version="1.0" encoding="utf-8" ?>
<log4net>
    <appender name="RollingFileAppender" type="log4net.Appender.RollingFileAppender">
        <param name="File" value="logs\log.txt" />
        <param name="AppendToFile" value="true" />
        <rollingStyle value="Size" />
        <maxSizeRollBackups value="5" />
        <maximumFileSize value="10MB" />
        <staticLogFileName value="true" />
        <layout type="log4net.Layout.PatternLayout">
            <param name="ConversionPattern" value="%date [%thread] %-5level %logger - %message%newline" />
        </layout>
    </appender>

    <root>
        <level value="INFO" />
        <appender-ref ref="RollingFileAppender" />
    </root>
</log4net>

上述配置文件中，appender定义了输出的方式，RollingFileAppender表示按照文件大小轮转输出，logging的信息全部会被写到 logs\log.txt 文件中。root则是定义了级别，如INFO级别及更高的日志信息会被输出到RollingFileAppender中。

在Startup.cs文件的Configure()方法中添加如下代码，从而使log4net可以读取配置文件：

log4net.Config.XmlConfigurator.Configure(new FileInfo("log4net.config"));

3. 在WebApi中使用log4net

3.1 在控制器中使用log4net

为了在WebApi的控制器中使用log4net，首先需要在控制器中引入log4net组件：

using log4net;

之后在控制器中声明一个log4net的实例：

private static readonly ILog log = LogManager.GetLogger(typeof(ValuesController));

在控制器中使用log4net输出日志的方法：

log.Info("Some log information.");

示例代码：

using Microsoft.AspNetCore.Mvc;
using System.Collections.Generic;
using log4net;

namespace WebApplication1.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class ValuesController : ControllerBase
    {
        private static readonly ILog log = LogManager.GetLogger(typeof(ValuesController));

        [HttpGet]
        public IEnumerable<string> Get()
        {
            log.Info("Get() called.");
            return new string[] { "value1", "value2" };
        }
    }
}

3.2 在中间件中使用log4net

通过在WebApi的中间件中使用log4net，我们可以对请求/响应进行记录。首先，新增一个log4net实例，用于记录中间件部分的信息：

private static readonly ILog middlewareLog = LogManager.GetLogger("Middleware");

然后添加一个log4net中间件：

app.Use(async (context, next) =>
{
    middlewareLog.InfoFormat("Received request {0} {1}", context.Request.Method, context.Request.Path.Value);
    await next.Invoke();
    middlewareLog.InfoFormat("Sending response {0}", context.Response.StatusCode);
});

完整示例代码：

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;
using System.Collections.Generic;
using log4net;

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.AddControllers();
            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1", new OpenApiInfo { Title = "WebApplication1", Version = "v1" });
            });
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
                app.UseSwagger();
                app.UseSwaggerUI(c => c.SwaggerEndpoint("/swagger/v1/swagger.json", "WebApplication1 v1"));
            }

            var log4netConfig = new FileInfo(Path.Combine(env.ContentRootPath, "log4net.config"));
            log4net.Config.XmlConfigurator.ConfigureAndWatch(log4netConfig);

            var log = LogManager.GetLogger(typeof(Program));
            var middlewareLog = LogManager.GetLogger("Middleware");

            app.Use(async (context, next) =>
            {
                middlewareLog.InfoFormat("Received request {0} {1}", context.Request.Method, context.Request.Path.Value);
                await next.Invoke();
                middlewareLog.InfoFormat("Sending response {0}", context.Response.StatusCode);
            });

            app.Use(async (context, next) =>
            {
                log.Info("Test1 middleware");
                await next.Invoke();
                log.Info("Test1 middleware end");
            });

            app.UseRouting();

            app.UseEndpoints(endpoints =>
            {
                endpoints.MapControllers();
            });
        }
    }
}

以上就是“.NET6在WebApi中使用日志组件log4net”的完整攻略，希望对你有帮助。