asp.net core 3.0在Microsoft.Extensions.Logging中添加log4net支持

1. 引入log4net、Microsoft.Extensions.Logging.Log4Net.AspNetCore包

2. 添加log4net配置文件

3. 在Program中添加如下代码：

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureLogging((context, logger) =>
        {
            logger.ClearProviders();

            logger.AddLog4Net(new Log4NetProviderOptions()
            {
                Log4NetConfigFileName = "Config/log4net.xml",
                Watch = true
            });
        })
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseStartup<Startup>();
        });

　　

4. 在需要记录日志的类中通过构造函数引入：

public class ActionExceptionHandlerAttribute : Attribute, IActionFilter
{
    private readonly ILogger<ActionExceptionHandlerAttribute> _logger;

    public ActionExceptionHandlerAttribute(ILogger<ActionExceptionHandlerAttribute> logger)
    {
        _logger = logger;
    }
}