.NET Core設定檔載入與DI注入設定數據

var config = new ConfigurationBuilder()
                .AddInMemoryCollection()    //将配置文件的数据加载到内存中
                .SetBasePath(Directory.GetCurrentDirectory())   //指定配置文件所在的目录
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)  //指定加载的配置文件
                .Build();    //编译成对象  
            Console.WriteLine(config["test"]);  //获取配置中的数据
            config["test"] = "test test";   //修改配置对象的数据，配置对象的数据是可以被修改的
            Console.WriteLine(config["test11"]);    //获取配置文件中不存在数据也是不会报错的
            Console.WriteLine(config["theKey:nextKey"]);    //获取：theKey -> nextKey 的值

{
  "test": "testVal",
  "theKey": {
    "nextKey": "keyVal"
  }
}

var sp = new ServiceCollection()
                .AddOptions()   //注入IOptions<T>，这样就可以在DI容器中获取IOptions<T>了
                .Configure<TestCls>(config.GetSection("TestCls"))   //注入配置数据
                //也可以对注入的配置数据进行修改
                .Configure<TestCls>(t =>
                {
                    t.Name = "Jame"; //修改Name的值
                })
                .BuildServiceProvider();    //编译

            var test = sp.GetService<IOptions<TestCls>>();    //获取注入的配置数据对象
            Console.WriteLine(JsonConvert.SerializeObject(test.Value));    //{"Name":"Jame","Age":123}

            //下面的代码中检验Configure注入的配置数据对象是单例模式的(.NET Core中DI容器的三种生命周期：Singleton(单例), Scoped(作用域), Transient(瞬态))
            var test1 = sp.GetService<IOptions<TestCls>>();
            Console.WriteLine(test == test1);   //true
            //创建一个新的作用域获取配置数据对象
            var test2 = sp.GetService<IServiceScopeFactory>().CreateScope().ServiceProvider.GetService<IOptions<TestCls>>();
            Console.WriteLine(test == test2);   //true

         public class TestCls
         {
             public string Name { get; set; }
             public int Age { get; set; }
         }

{
  "TestCls": {
    "Name": "Tom",
    "Age": 123
  }
}

var builder = new ConfigurationBuilder()
                .AddInMemoryCollection()
                .SetBasePath(env.ContentRootPath)
                .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
                .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);
            Configuration = builder.Build();

services.AddOptions()        //注入IOptions<T>
                .Configure<TestCls>(Configuration.GetSection(nameof(TestCls)))
                .Configure<TestCls>(test =>
                {
                    test.Name = "Jame"; //修改Name的值
                });

{
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Debug",
      "System": "Information",
      "Microsoft": "Information"
    }
  },
  "TestCls": {
    "Name": "Tom",
    "Age": 123
  }
}

[Route("api/[controller]")]
    public class ValuesController : Controller
    {
        IOptions<TestCls> _test;
        public ValuesController(IOptions<TestCls> test)
        {
            _test = test;
        }
        [HttpGet]
        public string Gets()
        {
            return JsonConvert.SerializeObject(_test.Value);
        }