根据请求配置不同的appsettings POCO

{
  "DefaultSetting": "Default Value"
}

{
  "CustomSetting": "Custom Value"
}

public class AppSettings
{
    public string DefaultSetting { get; set; }
}

public class CustomAppSettings : AppSettings
{
    public string CustomSetting { get; set; }
}

var builder = WebApplication.CreateBuilder(args);

// 加载默认配置
builder.Configuration.AddJsonFile("appsettings.json", optional: true, reloadOnChange: true);

// 根据请求加载自定义配置
if (/* 条件判断 */)
{
    builder.Configuration.AddJsonFile("appsettings.Custom.json", optional: true, reloadOnChange: true);
}

var app = builder.Build();

// 注册配置对象
builder.Services.AddSingleton(builder.Configuration.Get<CustomAppSettings>());

app.Run();

try
{
    var customSettings = builder.Configuration.Get<CustomAppSettings>();
    Console.WriteLine($"DefaultSetting: {customSettings.DefaultSetting}");
    Console.WriteLine($"CustomSetting: {customSettings.CustomSetting}");
}
catch (Exception ex)
{
    Console.WriteLine($"Error loading configuration: {ex.Message}");
}