serilog-asp.net

 这是 serilog-asp.net 的demo:   https://github.com/serilog/serilog-aspnetcore/blob/dev/samples/Sample/Program.cs

开始是这一句话

// The initial "bootstrap" logger is able to log errors during start-up. It's completely replaced by the
// logger configured in `UseSerilog()` below, once configuration and dependency-injection have both been
// set up successfully.
            Log.Logger = new LoggerConfiguration()
                .WriteTo.Console()
                .CreateBootstrapLogger();

这个 UseSerilog()  里面有个参数  bool preserveStaticLogger =false, 如果不传(默认false), 最终将会被替换。

而如果替换，上面的代码，就要写成 CreateBootstrapLogger(), 而不是 CreateLogger()

这关系到  UseSerilog() 这里面这句话的转换结果。

var reloadable = Log.Logger as ReloadableLogger;

UseSerilog() 的后面  依赖注入了  ILoggerFactory，实现的是SerilogLoggerFactory。

SerilogLoggerFactory 中 new SerilogLoggerProvider(), 后者又new SerilogLogger(this, _logger, name)，这样定义  SerilogLogger : Microsoft.Extensions.Logging.ILogger

在这个方法中，_logger 参数是null, 传了一路，最后赋给默认值 Serilog.Log.Logger

 这会让 ILogger 最终使用到Serilog.Log.Logger。