ASP.NET Core使用选项方式读取配置

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "DB": {
    "DbType": "SQLServer",
    "Connection": "Data Source = .Catalog=DemoDB; Integrated Security = true"
  },
  "Smtp": {
    "Server": "smtp.youzack.com",
    "UserName": "zack",
    "Password": "hello888",
  },
    "AllowedHosts": "*"
  }

public class DbSettings
{
    public string? DbType { get; set; }
    public string? ConnectionString { get; set; }

}

 public class SmtpSettings
 {
     public string? Server { get; set; }
     public string? UserName { get; set; }
     public string? Password { get; set; }
 }

由于使用选项方式读取配置的时候，需要和依赖注入一起使用，因此我们需要创建一个类用于获取注入的选项值。声明接收选项注入的对象的类型不能直接使用DbSettings、SmtpSettings，而要使用IOptions、IOptionsMonitor、IOptionsSnapshot等泛型接口类型，因为它们可以帮我们处理容器生命周期、配置刷新等。它们的区别在于，IOptions在配置改变后，我们不能读到新的值，必须重启程序才可以读到新的值；IOptionsMonitor在配置改变后，我们能读到新的值；IOptionsSnapshot也是在配置改变后，我们能读到新的值，和IOptionsMonitor不同的是，在同一个范围内IOptionsMonitor会保持一致性。

 public class Demo
 {
     private readonly IOptionsSnapshot<DbSettings> optDbsettings;
     private readonly IOptionsSnapshot<SmtpSettings> optSmtpSettings;

     public Demo(IOptionsSnapshot<DbSettings> optDbsettings, IOptionsSnapshot<SmtpSettings> optSmtpSettings)
     {
         this.optDbsettings = optDbsettings;
         this.optSmtpSettings = optSmtpSettings;
     }


     public void Test()
     {
         var db = optDbsettings.Value;
         Console.WriteLine($"数据库：{db.DbType},{db.ConnectionString}");
         var smtp = optSmtpSettings.Value;
         Console.WriteLine($"smtp:{smtp.Server},{smtp.UserName},{smtp.Password}");
     }

 }

 var configurationBuilder = new ConfigurationBuilder();
 configurationBuilder.AddJsonFile("appsettings.json", optional: false, reloadOnChange: true);
 IConfigurationRoot config = configurationBuilder.Build();
 ServiceCollection services = new ServiceCollection();
 services.AddOptions().Configure<DbSettings>(e => config.GetSection("DB").Bind(e))
     .Configure<SmtpSettings>(e => config.GetSection("Smtp").Bind(e));
 services.AddTransient<Demo>();
 using (var sp = services.BuildServiceProvider())
 {
     while (true)
     {
         using (var scope = sp.CreateScope())
         {
             var spScope = scope.ServiceProvider;
             var demo = spScope.GetRequiredService<Demo>();
             demo.Test();
         }
         Console.WriteLine("可以修改配置了");
         Console.ReadKey();
     }
 }

运行exe
![[assets/ASP.NET Core使用选项方式读取配置/file-20250308123308971.png]]

修改配置文件保存
![[assets/ASP.NET Core使用选项方式读取配置/file-20250308123433037.png]]