appsetting.json

{   
  "Settings": {      
    "ProjectName": "Sample Project"   
  }
}

定义一个具有相同属性名的类:

 public class Settings
 {
     public string ProjectName { get; set; }  
 }

在Startup.cs中添加配置:

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<Settings>(Configuration.GetSection("Settings")); 
}

注入控制器:

public class TestController : Controller
{
    private readonly Settings _settings;       
    
    public TestController(IOptions<Settings> settings)
    {
         _settings = settings.Value;
    }
       
    [AllowAnonymous]
    public async Task<IActionResult> test()
    {
        var _projectname = _settings.ProjectName;
                
        return View();
    }
}

    public static void GetSection()
    {
        Configuration = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json")
            .Build();

        string BConfig = Configuration.GetSection("ConnectionStrings")["BConnection"];

    }

如果以上解决方案没有帮助，您可以参考此链接。对我来说，命名选项支持使用IConfigureNamedOptions工作!你可能还会发现其他方法可能对你有帮助。

使用IConfigureNamedOptions支持命名选项

在Startup类的构造函数中，可以访问appsettings。json和使用注入的IConfiguration对象的许多其他设置:

Startup.cs构造函数

    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;

        //here you go
        var myvalue = Configuration["Grandfather:Father:Child"];

    }

public IConfiguration Configuration { get; }

json的内容

  {
  "Grandfather": {
    "Father": {
      "Child": "myvalue"
    }
  }

从Asp.net core 2.2到以上版本，你可以编写如下代码:

步骤1。创建一个AppSettings类文件。

这个文件包含一些帮助从appsettings中按键获取值的方法。json文件。如下代码所示:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace ReadConfig.Bsl
{
  public class AppSettings
  {
      private static AppSettings _instance;
      private static readonly object ObjLocked = new object();
      private IConfiguration _configuration;

      protected AppSettings()
      {
      }

      public void SetConfiguration(IConfiguration configuration)
      {
          _configuration = configuration;
      }

      public static AppSettings Instance
      {
          get
          {
              if (null == _instance)
              {
                  lock (ObjLocked)
                  {
                      if (null == _instance)
                          _instance = new AppSettings();
                  }
              }
              return _instance;
          }
      }

      public string GetConnection(string key, string defaultValue = "")
      {
          try
          {
              return _configuration.GetConnectionString(key);
          }
          catch
          {
              return defaultValue;
          }
      }

      public T Get<T>(string key = null)
      {
          if (string.IsNullOrWhiteSpace(key))
              return _configuration.Get<T>();
          else
              return _configuration.GetSection(key).Get<T>();
      }

      public T Get<T>(string key, T defaultValue)
      {
          if (_configuration.GetSection(key) == null)
              return defaultValue;

          if (string.IsNullOrWhiteSpace(key))
              return _configuration.Get<T>();
          else
              return _configuration.GetSection(key).Get<T>();
      }

      public static T GetObject<T>(string key = null)
      {
          if (string.IsNullOrWhiteSpace(key))
              return Instance._configuration.Get<T>();
          else
          {
              var section = Instance._configuration.GetSection(key);
              return section.Get<T>();
          }
      }

      public static T GetObject<T>(string key, T defaultValue)
      {
          if (Instance._configuration.GetSection(key) == null)
              return defaultValue;

          if (string.IsNullOrWhiteSpace(key))
              return Instance._configuration.Get<T>();
          else
              return Instance._configuration.GetSection(key).Get<T>();
      }
  }
}

步骤2。AppSettings对象的初始配置

我们需要声明和加载appsettings。json文件，加载AppSettings对象的配置信息。我们将在Startup.cs文件的构造函数中完成这项工作。 请注意行AppSettings.Instance.SetConfiguration(配置);

public Startup(IHostingEnvironment evm)
{
    var builder = new ConfigurationBuilder()
      .SetBasePath(evm.ContentRootPath)
      .AddJsonFile("appsettings.json", true, true)
      .AddJsonFile($"appsettings.{evm.EnvironmentName}.json", true)
      .AddEnvironmentVariables();
    Configuration = builder.Build(); // load all file config to Configuration property 
    AppSettings.Instance.SetConfiguration(Configuration);       
}

现在我有了appsettings。Json文件与一些关键字如下:

{
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft": "Warning",
      "Microsoft.Hosting.Lifetime": "Information"
    }
  },
  "AllowedHosts": "*",
  "ConnectionStrings": {
    "ConnectionString": "Data Source=localhost;Initial Catalog=ReadConfig;Persist Security Info=True;User ID=sa;Password=12345;"
  },
  "MailConfig": {
    "Servers": {
      "MailGun": {
        "Pass": "65-1B-C9-B9-27-00",
        "Port": "587",
        "Host": "smtp.gmail.com"
      }
    },
    "Sender": {
      "Email": "example@gmail.com",
      "Pass": "123456"
    }
  }
}

步骤3。从操作中读取配置值

我在Home控制器中演示一个动作，如下所示:

public class HomeController : Controller
{
    public IActionResult Index()
    {
        var connectionString = AppSettings.Instance.GetConnection("ConnectionString");
        var emailSender = AppSettings.Instance.Get<string>("MailConfig:Sender:Email");
        var emailHost = AppSettings.Instance.Get<string>("MailConfig:Servers:MailGun:Host");

        string returnText = " 1. Connection String \n";
        returnText += "  " +connectionString;
        returnText += "\n 2. Email info";
        returnText += "\n Sender : " + emailSender;
        returnText += "\n Host : " + emailHost;

        return Content(returnText);
    }
}

结果如下:

点击查看结果

appsetting.json

{   
  "Settings": {      
    "ProjectName": "Sample Project"   
  }
}

定义一个具有相同属性名的类:

 public class Settings
 {
     public string ProjectName { get; set; }  
 }

在Startup.cs中添加配置:

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<Settings>(Configuration.GetSection("Settings")); 
}

注入控制器:

public class TestController : Controller
{
    private readonly Settings _settings;       
    
    public TestController(IOptions<Settings> settings)
    {
         _settings = settings.Value;
    }
       
    [AllowAnonymous]
    public async Task<IActionResult> test()
    {
        var _projectname = _settings.ProjectName;
                
        return View();
    }
}