public static IHostBuilder CreateDefaultBuilder(string[] args)
    {
      var builder = new HostBuilder();
"DOTNET_");
        if (args != null)
        {
          config.AddCommandLine(args);
        }
      });
"appsettings.json", optional: true, reloadOnChange: true)
           .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true, reloadOnChange: true);
"text-align: center">

将文件读入配置时，会创建一下唯一的分层健来保存配置值：

  
Logging:LogLevel:Default
  
Logging:LogLevel:System
  
Logging:LogLevel:Microsoft
  
Logging:LogLevel:Microsoft.Hosting.Lifetime
  
AllowedHosts



var jsonValue = $"AllowedHosts:{_config["AllowedHosts"]}"+ "\r\n";
      jsonValue += "Logging:LogLevel:Default：" + _config.GetValue<string>("Logging:LogLevel:Default")+ "\r\n";
"---" + _config.GetSection("Logging:LogLevel:System");
      jsonValue += "Logging:LogLevel:System：" + _config.GetSection("Logging:LogLevel:System").Value+ "\r\n\n";
     
      var logSection = _config.GetSection("Logging:LogLevel");
      var configurationSections = logSection.GetChildren();
      foreach (var sections in configurationSections) 
      {
        jsonValue += $"{sections.Path}:{sections.Value}";
        jsonValue += "\r\n";
      }
      jsonValue += "\r\n";



配置指定json文件绑定至类
新建一个json文件-AAAppSettings.json


{
 "AA": {
  "RabbitMqHostUrl": "rabbitmq://localhost:5672",
  "RabbitMqHostName": "localhost",
  "RabbitMqUserName": "admin",
  "RabbitMqPassword": "123"
 }
}


使用ConfigureAppConfiguration方法配置指定的json文件


public static IHostBuilder CreateHostBuilder(string[] args) =>
      Host.CreateDefaultBuilder(args)
      .ConfigureAppConfiguration((hostingContext, config) =>
      {
        config.SetBasePath(Directory.GetCurrentDirectory());
        config.AddJsonFile("AAAppSettings.json", optional: true, reloadOnChange: true);
      })


使用bind方法绑定到新建的类上如：


public partial class AAConfig
  {
    public string RabbitMqHostUrl { get; set; }
    public string RabbitMqHostName { get; set; }
    public string RabbitMqUserName { get; set; }
    public string RabbitMqPassword { get; set; }
  }




var aaConfig = new AAConfig();
_config.GetSection("AA").Bind(aaConfig);
jsonValue += aaConfig.RabbitMqHostUrl + "\r\n";
jsonValue += aaConfig.RabbitMqHostName + "\r\n";
jsonValue += aaConfig.RabbitMqUserName + "\r\n";
jsonValue += aaConfig.RabbitMqPassword + "\r\n";
return jsonValue;


运行输出：