不确定我在这里错过了什么,但我无法从我的应用程序设置中获得值。Json在我的。net核心应用程序。我有我的appsettings。json:

{
    "AppSettings": {
        "Version": "One"
    }
}

启动:

public class Startup
{
    private IConfigurationRoot _configuration;
    public Startup(IHostingEnvironment env)
    {
        _configuration = new ConfigurationBuilder()
    }
    public void ConfigureServices(IServiceCollection services)
    {
      //Here I setup to read appsettings        
      services.Configure<AppSettings>(_configuration.GetSection("AppSettings"));
    }
}

模型:

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

控制器:

public class HomeController : Controller
{
    private readonly AppSettings _mySettings;

    public HomeController(IOptions<AppSettings> settings)
    {
        //This is always null
        _mySettings = settings.Value;
    }
}

_mySettings总是空的。我是不是遗漏了什么?


当前回答

程序与启动课程

ASP。NET Core 6.x

ASP。NET Core 6。x在Program类中带来了另一个大的变化:

如果您选择使用顶级语句,则没有Program.Main()样板 隐式使用指令 没有启动类,因为所有东西都在程序文件中 介绍WebApplication和WebApplicationBuilder

有人说,这些变化有利于新人学习ASP。净的核心。我的感觉正好相反。我认为程序和启动的分离更有意义,至少对我来说。

无论如何……

这是Program.cs的样子:

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);

        builder.Services.AddControllersWithViews();

        var app = builder.Build();

        if (!app.Environment.IsDevelopment())
        {
            app.UseExceptionHandler("/errors");
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseStaticFiles();

        app.UseRouting();

        app.UseAuthorization();

        app.MapControllerRoute(
            name: "areaRoute",
            pattern: "{area:exists}/{controller=home}/{action=index}/{id?}");
            
        app.MapControllerRoute(
            name: "default",
            pattern: "{controller=home}/{action=index}/{id?}");

        app.Run();
    }
}

你可以区分WebApplication.CreateBuilder()和builder.Build()之间的部分是旧的ConfigureServices(IServiceCollection服务)用来做的事情。app.Run()之前的部分是Startup中旧的Configure()所做的。

最重要的是,IConfiguration被注入到管道中,所以你可以在你的控制器上使用它。

ASP。NET Core 3。X至5

ASP。NET Core 3。X带来了一些变化,试图支持其他方法,如worker services,所以它用更通用的主机构建器取代了web主机:

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            }; 
    }
}

Startup类看起来非常类似于2。不过是X版本。

ASP。NET Core 2.x

你不需要在启动构造函数中新建IConfiguration。它的实现将由DI系统注入。

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        BuildWebHost(args).Run();
    }

    public static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
            .Build();            
}

// Startup.cs
public class Startup
{
    public IHostingEnvironment HostingEnvironment { get; private set; }
    public IConfiguration Configuration { get; private set; }

    public Startup(IConfiguration configuration, IHostingEnvironment env)
    {
        this.HostingEnvironment = env;
        this.Configuration = configuration;
    }
}

ASP。NET Core 1.x

您需要告诉Startup加载appsettings文件。

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        var host = new WebHostBuilder()
            .UseKestrel()
            .UseContentRoot(Directory.GetCurrentDirectory())
            .UseIISIntegration()
            .UseStartup<Startup>()
            .UseApplicationInsights()
            .Build();

        host.Run();
    }
}

//Startup.cs
public class Startup
{
    public IConfigurationRoot Configuration { get; private set; }

    public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddEnvironmentVariables();

        this.Configuration = builder.Build();
    }
    ...
}

获得值

有很多方法可以从应用程序设置中获得你配置的值:

使用ConfigurationBuilder的简单方法。GetValue < T > 使用选项模式

比如说你的appsettings。Json是这样的:

{
    "ConnectionStrings": {
        ...
    },
    "AppIdentitySettings": {
        "User": {
            "RequireUniqueEmail": true
        },
        "Password": {
            "RequiredLength": 6,
            "RequireLowercase": true,
            "RequireUppercase": true,
            "RequireDigit": true,
            "RequireNonAlphanumeric": true
        },
        "Lockout": {
            "AllowedForNewUsers": true,
            "DefaultLockoutTimeSpanInMins": 30,
            "MaxFailedAccessAttempts": 5
        }
    },
    "Recaptcha": { 
        ...
    },
    ...
}

简单的方法

你可以将整个配置注入到你的控制器/类的构造函数中(通过IConfiguration),并通过指定的键获取你想要的值:

public class AccountController : Controller
{
    private readonly IConfiguration _config;

    public AccountController(IConfiguration config)
    {
        _config = config;
    }

    [AllowAnonymous]
    public IActionResult ResetPassword(int userId, string code)
    {
        var vm = new ResetPasswordViewModel
        {
            PasswordRequiredLength = _config.GetValue<int>(
                "AppIdentitySettings:Password:RequiredLength"),
            RequireUppercase = _config.GetValue<bool>(
                "AppIdentitySettings:Password:RequireUppercase")
        };

        return View(vm);
    }
}

选择模式

ConfigurationBuilder。如果你只需要应用程序设置中的一个或两个值,那么>工作得很好。但如果你想从应用程序设置中获得多个值,或者你不想在多个地方硬编码那些关键字字符串,使用选项模式可能更容易。选项模式使用类来表示层次结构/结构。

使用选项模式:

定义类来表示结构 注册这些类绑定到的配置实例 将IOptions<T>注入到你想获取值的控制器/类的构造函数中

1. 定义配置类来表示结构

你可以定义具有属性的类,这些属性需要与应用程序设置中的键完全匹配。类的名称不必与应用设置中的section名称匹配:

public class AppIdentitySettings
{
    public UserSettings User { get; set; }
    public PasswordSettings Password { get; set; }
    public LockoutSettings Lockout { get; set; }
}

public class UserSettings
{
    public bool RequireUniqueEmail { get; set; }
}

public class PasswordSettings
{
    public int RequiredLength { get; set; }
    public bool RequireLowercase { get; set; }
    public bool RequireUppercase { get; set; }
    public bool RequireDigit { get; set; }
    public bool RequireNonAlphanumeric { get; set; }
}

public class LockoutSettings
{
    public bool AllowedForNewUsers { get; set; }
    public int DefaultLockoutTimeSpanInMins { get; set; }
    public int MaxFailedAccessAttempts { get; set; }
}

2. 注册配置实例

然后你需要在启动时在ConfigureServices()中注册这个配置实例:

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
...

namespace DL.SO.UI.Web
{
    public class Startup
    {
        ...
        public void ConfigureServices(IServiceCollection services)
        {
            ...
            var identitySettingsSection = 
                _configuration.GetSection("AppIdentitySettings");
            services.Configure<AppIdentitySettings>(identitySettingsSection);
            ...
        }
        ...
    }
}

ASP。NET Core 6.x

由于我在开头提到的ASP。NET Core 6。x,你需要绑定该section并将其添加到DI,如下所示:

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);

        builder.Services.AddControllersWithViews();

        builder.Services.Configure<AppIdentitySettings>(
            builder.Configuration.GetSection("AppIdentitySettings")
        );

        var app = builder.Build();

        ...

        app.Run();
    }
}

你可以在这里阅读更多相关内容。

3.注入IOptions

最后在你想要获取值的控制器/类上,你需要通过构造函数注入IOptions<AppIdentitySettings>:

public class AccountController : Controller
{
    private readonly AppIdentitySettings _appIdentitySettings;

    public AccountController(IOptions<AppIdentitySettings> appIdentitySettingsAccessor)
    {
        _appIdentitySettings = appIdentitySettingsAccessor.Value;
    }

    [AllowAnonymous]
    public IActionResult ResetPassword(int userId, string code)
    {
        var vm = new ResetPasswordViewModel
        {
            PasswordRequiredLength = _appIdentitySettings.Password.RequiredLength,
            RequireUppercase = _appIdentitySettings.Password.RequireUppercase
        };

        return View(vm);
    }
}

其他回答

程序与启动课程

ASP。NET Core 6.x

ASP。NET Core 6。x在Program类中带来了另一个大的变化:

如果您选择使用顶级语句,则没有Program.Main()样板 隐式使用指令 没有启动类,因为所有东西都在程序文件中 介绍WebApplication和WebApplicationBuilder

有人说,这些变化有利于新人学习ASP。净的核心。我的感觉正好相反。我认为程序和启动的分离更有意义,至少对我来说。

无论如何……

这是Program.cs的样子:

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);

        builder.Services.AddControllersWithViews();

        var app = builder.Build();

        if (!app.Environment.IsDevelopment())
        {
            app.UseExceptionHandler("/errors");
            app.UseHsts();
        }

        app.UseHttpsRedirection();
        app.UseStaticFiles();

        app.UseRouting();

        app.UseAuthorization();

        app.MapControllerRoute(
            name: "areaRoute",
            pattern: "{area:exists}/{controller=home}/{action=index}/{id?}");
            
        app.MapControllerRoute(
            name: "default",
            pattern: "{controller=home}/{action=index}/{id?}");

        app.Run();
    }
}

你可以区分WebApplication.CreateBuilder()和builder.Build()之间的部分是旧的ConfigureServices(IServiceCollection服务)用来做的事情。app.Run()之前的部分是Startup中旧的Configure()所做的。

最重要的是,IConfiguration被注入到管道中,所以你可以在你的控制器上使用它。

ASP。NET Core 3。X至5

ASP。NET Core 3。X带来了一些变化,试图支持其他方法,如worker services,所以它用更通用的主机构建器取代了web主机:

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            }; 
    }
}

Startup类看起来非常类似于2。不过是X版本。

ASP。NET Core 2.x

你不需要在启动构造函数中新建IConfiguration。它的实现将由DI系统注入。

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        BuildWebHost(args).Run();
    }

    public static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
            .Build();            
}

// Startup.cs
public class Startup
{
    public IHostingEnvironment HostingEnvironment { get; private set; }
    public IConfiguration Configuration { get; private set; }

    public Startup(IConfiguration configuration, IHostingEnvironment env)
    {
        this.HostingEnvironment = env;
        this.Configuration = configuration;
    }
}

ASP。NET Core 1.x

您需要告诉Startup加载appsettings文件。

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        var host = new WebHostBuilder()
            .UseKestrel()
            .UseContentRoot(Directory.GetCurrentDirectory())
            .UseIISIntegration()
            .UseStartup<Startup>()
            .UseApplicationInsights()
            .Build();

        host.Run();
    }
}

//Startup.cs
public class Startup
{
    public IConfigurationRoot Configuration { get; private set; }

    public Startup(IHostingEnvironment env)
    {
        var builder = new ConfigurationBuilder()
            .SetBasePath(env.ContentRootPath)
            .AddJsonFile("appsettings.json", optional: false, reloadOnChange: true)
            .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true)
            .AddEnvironmentVariables();

        this.Configuration = builder.Build();
    }
    ...
}

获得值

有很多方法可以从应用程序设置中获得你配置的值:

使用ConfigurationBuilder的简单方法。GetValue < T > 使用选项模式

比如说你的appsettings。Json是这样的:

{
    "ConnectionStrings": {
        ...
    },
    "AppIdentitySettings": {
        "User": {
            "RequireUniqueEmail": true
        },
        "Password": {
            "RequiredLength": 6,
            "RequireLowercase": true,
            "RequireUppercase": true,
            "RequireDigit": true,
            "RequireNonAlphanumeric": true
        },
        "Lockout": {
            "AllowedForNewUsers": true,
            "DefaultLockoutTimeSpanInMins": 30,
            "MaxFailedAccessAttempts": 5
        }
    },
    "Recaptcha": { 
        ...
    },
    ...
}

简单的方法

你可以将整个配置注入到你的控制器/类的构造函数中(通过IConfiguration),并通过指定的键获取你想要的值:

public class AccountController : Controller
{
    private readonly IConfiguration _config;

    public AccountController(IConfiguration config)
    {
        _config = config;
    }

    [AllowAnonymous]
    public IActionResult ResetPassword(int userId, string code)
    {
        var vm = new ResetPasswordViewModel
        {
            PasswordRequiredLength = _config.GetValue<int>(
                "AppIdentitySettings:Password:RequiredLength"),
            RequireUppercase = _config.GetValue<bool>(
                "AppIdentitySettings:Password:RequireUppercase")
        };

        return View(vm);
    }
}

选择模式

ConfigurationBuilder。如果你只需要应用程序设置中的一个或两个值,那么>工作得很好。但如果你想从应用程序设置中获得多个值,或者你不想在多个地方硬编码那些关键字字符串,使用选项模式可能更容易。选项模式使用类来表示层次结构/结构。

使用选项模式:

定义类来表示结构 注册这些类绑定到的配置实例 将IOptions<T>注入到你想获取值的控制器/类的构造函数中

1. 定义配置类来表示结构

你可以定义具有属性的类,这些属性需要与应用程序设置中的键完全匹配。类的名称不必与应用设置中的section名称匹配:

public class AppIdentitySettings
{
    public UserSettings User { get; set; }
    public PasswordSettings Password { get; set; }
    public LockoutSettings Lockout { get; set; }
}

public class UserSettings
{
    public bool RequireUniqueEmail { get; set; }
}

public class PasswordSettings
{
    public int RequiredLength { get; set; }
    public bool RequireLowercase { get; set; }
    public bool RequireUppercase { get; set; }
    public bool RequireDigit { get; set; }
    public bool RequireNonAlphanumeric { get; set; }
}

public class LockoutSettings
{
    public bool AllowedForNewUsers { get; set; }
    public int DefaultLockoutTimeSpanInMins { get; set; }
    public int MaxFailedAccessAttempts { get; set; }
}

2. 注册配置实例

然后你需要在启动时在ConfigureServices()中注册这个配置实例:

using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
...

namespace DL.SO.UI.Web
{
    public class Startup
    {
        ...
        public void ConfigureServices(IServiceCollection services)
        {
            ...
            var identitySettingsSection = 
                _configuration.GetSection("AppIdentitySettings");
            services.Configure<AppIdentitySettings>(identitySettingsSection);
            ...
        }
        ...
    }
}

ASP。NET Core 6.x

由于我在开头提到的ASP。NET Core 6。x,你需要绑定该section并将其添加到DI,如下所示:

// Program.cs
public class Program
{
    public static void Main(string[] args)
    {
        var builder = WebApplication.CreateBuilder(args);

        builder.Services.AddControllersWithViews();

        builder.Services.Configure<AppIdentitySettings>(
            builder.Configuration.GetSection("AppIdentitySettings")
        );

        var app = builder.Build();

        ...

        app.Run();
    }
}

你可以在这里阅读更多相关内容。

3.注入IOptions

最后在你想要获取值的控制器/类上,你需要通过构造函数注入IOptions<AppIdentitySettings>:

public class AccountController : Controller
{
    private readonly AppIdentitySettings _appIdentitySettings;

    public AccountController(IOptions<AppIdentitySettings> appIdentitySettingsAccessor)
    {
        _appIdentitySettings = appIdentitySettingsAccessor.Value;
    }

    [AllowAnonymous]
    public IActionResult ResetPassword(int userId, string code)
    {
        var vm = new ResetPasswordViewModel
        {
            PasswordRequiredLength = _appIdentitySettings.Password.RequiredLength,
            RequireUppercase = _appIdentitySettings.Password.RequireUppercase
        };

        return View(vm);
    }
}

ASP。NET Core 3.1你可以遵循以下指南:

https://learn.microsoft.com/en-us/aspnet/core/fundamentals/configuration/?view=aspnetcore-3.1

当您创建一个新的ASP。在Program.cs中,你会有如下的配置行:

Host.CreateDefaultBuilder(args)

这将启用以下功能:

ChainedConfigurationProvider : Adds an existing IConfiguration as a source. In the default configuration case, adds the host configuration and setting it as the first source for the app configuration. appsettings.json using the JSON configuration provider. appsettings.Environment.json using the JSON configuration provider. For example, appsettings.Production.json and appsettings.Development.json. App secrets when the app runs in the Development environment. Environment variables using the Environment Variables configuration provider. Command-line arguments using the Command-line configuration provider.

这意味着您可以注入IConfiguration并使用字符串键获取值,甚至是嵌套值。像IConfiguration“父母:孩子”;

例子:

appsettings.json

{
  "ApplicationInsights":
    {
        "Instrumentationkey":"putrealikeyhere"
    }
}

WeatherForecast.cs

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
    private static readonly string[] Summaries = new[]
    {
        "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
    };

    private readonly ILogger<WeatherForecastController> _logger;
    private readonly IConfiguration _configuration;

    public WeatherForecastController(ILogger<WeatherForecastController> logger, IConfiguration configuration)
    {
        _logger = logger;
        _configuration = configuration;
    }

    [HttpGet]
    public IEnumerable<WeatherForecast> Get()
    {
        var key = _configuration["ApplicationInsights:InstrumentationKey"];

        var rng = new Random();
        return Enumerable.Range(1, 5).Select(index => new WeatherForecast
        {
            Date = DateTime.Now.AddDays(index),
            TemperatureC = rng.Next(-20, 55),
            Summary = Summaries[rng.Next(Summaries.Length)]
        })
        .ToArray();
    }
}

只需创建一个AnyName.cs文件并粘贴以下代码。

using System;
using System.IO;
using Microsoft.Extensions.Configuration;

namespace Custom
{
    static class ConfigurationManager
    {
        public static IConfiguration AppSetting { get; }
        static ConfigurationManager()
        {
            AppSetting = new ConfigurationBuilder()
                    .SetBasePath(Directory.GetCurrentDirectory())
                    .AddJsonFile("YouAppSettingFile.json")
                    .Build();
        }
    }
}

必须替换YouAppSettingFile。Json文件名与您的文件名。 您的.json文件应该如下所示。

{
    "GrandParent_Key" : {
        "Parent_Key" : {
            "Child_Key" : "value1"
        }
    },
    "Parent_Key" : {
        "Child_Key" : "value2"
    },
    "Child_Key" : "value3"
}

现在你可以使用它了。 不要忘记在你想要使用的类中添加引用。

using Custom;

检索值的代码。

string value1 = ConfigurationManager.AppSetting["GrandParent_Key:Parent_Key:Child_Key"];
string value2 = ConfigurationManager.AppSetting["Parent_Key:Child_Key"];
string value3 = ConfigurationManager.AppSetting["Child_Key"];

像这样在这里添加所需的键。在这种情况下,它的securecookie:

在startup.cs中添加构造函数 公共启动(IConfiguration配置) { 配置=配置; } public IConfiguration Configuration {get;} 使用Configuration[" secucookie "]访问设置

假设在appsettings.json中有这样的值。

  "MyValues": {
    "Value1": "Xyz"
  }

方法一:不进行依赖注入

在.cs文件中:

static IConfiguration conf = (new ConfigurationBuilder().SetBasePath(Directory.GetCurrentDirectory()).AddJsonFile("appsettings.json").Build());
public static string myValue1= conf["MyValues:Value1"].ToString();

方法二:依赖注入(推荐)

在Startup.cs文件:

public IConfiguration Configuration { get; }
public Startup(IConfiguration configuration)
{
     Configuration = configuration;
}
public void ConfigureServices(IServiceCollection services)
{
     ...
     services.AddServices(Configuration);
}

在你的控制器中:

public class TestController : ControllerBase
{
    private string myValue1 { get; set; }
    public TestController(IConfiguration configuration)
    {
         this.myValue1 = configuration.GetValue<string>("MyValues:Value1");
    }
}