如何从 ASP.NET Core 中的 .json 文件读取 AppSettings 值

本文介绍了如何从 ASP.NET Core 中的 .json 文件读取 AppSettings 值的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我在文件 appsettings/Config .json 中设置了我的 AppSettings 数据，如下所示:

I have set up my AppSettings data in file appsettings/Config .json like this:

{ "AppSettings": { "token": "1234" } }

我在网上搜索了如何从 .json 文件中读取 AppSettings 值，但我没有得到任何有用的信息.

I have searched online on how to read AppSettings values from .json file, but I could not get anything useful.

我试过了:

var configuration = new Configuration(); var appSettings = configuration.Get("AppSettings"); // null var token = configuration.Get("token"); // null

我知道使用 ASP.NET 4.0 你可以做到这一点:

I know with ASP.NET 4.0 you can do this:

System.Configuration.ConfigurationManager.AppSettings["token"];

但是我如何在 ASP.NET Core 中做到这一点?

But how do I do this in ASP.NET Core?

推荐答案

这有一些曲折.我已修改此答案以与 ASP.NET Core 2.0 保持同步(截至 2018 年 2 月 26 日).

This has had a few twists and turns. I've modified this answer to be up to date with ASP.NET Core 2.0 (as of 26/02/2018).

这主要取自官方文档:

要使用 ASP.NET 应用程序中的设置，建议您仅在应用程序的 Startup 类中实例化一个 Configuration.然后，使用选项模式访问各个设置.假设我们有一个 appsettings.json 文件，如下所示:

To work with settings in your ASP.NET application, it is recommended that you only instantiate a Configuration in your application’s Startup class. Then, use the Options pattern to access individual settings. Let's say we have an appsettings.json file that looks like this:

{ "MyConfig": { "ApplicationName": "MyApp", "Version": "1.0.0" } }

我们有一个代表配置的 POCO 对象:

And we have a POCO object representing the configuration:

public class MyConfig { public string ApplicationName { get; set; } public int Version { get; set; } }

现在我们在Startup.cs中构建配置:

Now we build the configuration in Startup.cs:

public class Startup { public IConfigurationRoot Configuration { get; set; } public Startup(IHostingEnvironment env) { var builder = new ConfigurationBuilder() .SetBasePath(env.ContentRootPath) .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true); Configuration = builder.Build(); } }

请注意，appsettings.json 将在 .NET Core 2.0 中默认注册.如果需要，我们还可以为每个环境注册一个 appsettings.{Environment}.json 配置文件.

Note that appsettings.json will be registered by default in .NET Core 2.0. We can also register an appsettings.{Environment}.json config file per environment if needed.

如果我们想将我们的配置注入我们的控制器，我们需要在运行时注册它.我们通过 Startup.ConfigureServices 来实现:

If we want to inject our configuration to our controllers, we'll need to register it with the runtime. We do so via Startup.ConfigureServices:

public void ConfigureServices(IServiceCollection services) { services.AddMvc(); // Add functionality to inject IOptions<T> services.AddOptions(); // Add our Config object so it can be injected services.Configure<MyConfig>(Configuration.GetSection("MyConfig")); }

我们像这样注入它:

public class HomeController : Controller { private readonly IOptions<MyConfig> config; public HomeController(IOptions<MyConfig> config) { this.config = config; } // GET: /<controller>/ public IActionResult Index() => View(config.Value); }

完整的Startup类:

public class Startup { public IConfigurationRoot Configuration { get; set; } public Startup(IHostingEnvironment env) { var builder = new ConfigurationBuilder() .SetBasePath(env.ContentRootPath) .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true); Configuration = builder.Build(); } public void ConfigureServices(IServiceCollection services) { services.AddMvc(); // Add functionality to inject IOptions<T> services.AddOptions(); // Add our Config object so it can be injected services.Configure<MyConfig>(Configuration.GetSection("MyConfig")); } }