ASP.NET Core 2.2 基础知识(七) 选项模式 -云博客

ASP.NET Core 2.2 基础知识(七) 选项模式

# 前端 2024-05-05 15:31 0 47 来源：云博客

承接上一篇配置,

选项模式是专门用类来表示相关配置的服务.

基本选项配置

新建一个选项类,该类必须是包含无参数的构造函数的非抽象类.

 public class MyOptions { public MyOptions() { Id = 1; Name = "refuge"; } public int Id { get; set; } public string Name { get; set; } }

添加到服务容器,并绑定到配置:

 public class Startup { ...... public IConfiguration Configuration { get; } public void ConfigureServices(IServiceCollection services) { services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2); services.Configure<MyOptions>(Configuration); } ...... }

测试控制器:

 [Route("api/[controller]/[action]")] [ApiController] public class TestController : ControllerBase { private readonly IOptions<MyOptions> _options; public TestController(IOptions<MyOptions> options) { _options = options; _config = config; } public MyOptions Get() { return _options.Value; } }

结果:

通过委托配置选项

 public void ConfigureServices(IServiceCollection services) { services.Configure<MyOptions>(options => { //这些值会替代 MyOptions 构造函数中设置的值. //原因很简单,肯定是对象创建了,才会执行这个委托. options.Id = 2; options.Name = "refuge2"; }); }

通过文件配置简单选项

新建一个json文件:

{ "Id": 3, "Name": "refuge3"}

 public void ConfigureServices(IServiceCollection services) { services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2);  ConfigurationBuilder builder = new ConfigurationBuilder(); IConfigurationRoot config = builder.AddJsonFile(path: @"E:\Git\Source\Repos\MyOption\Demo1\jsonconfig.json", optional: true, reloadOnChange: true).Build(); services.Configure<MyOptions>(config); }

还可以读取文件中的某个节点配置简单选项

修改 json 文件,增加 subsection 节点.

{ "Id": 3, "Name": "refuge3", "SubSection": { "Id": 4, "Name": "refuge4" } }

 public void ConfigureServices(IServiceCollection services) { ConfigurationBuilder builder = new ConfigurationBuilder(); IConfigurationRoot config = builder.AddJsonFile(@"E:\Git\Source\Repos\MyOption\Demo1\jsonconfig.json", true, true).Build();  services.Configure<MyOptions>(config.GetSection("subsection")); }

上面这些例子中的获取到的 MyOptions 对象都是单例的.比如通过文件配置简单选项,即使 AddJsonFile 方法最后一个参数是 true ,配置数据也不会更新.要实现更新需要使用下面这个接口.

通过 IOptionsSnapshot 重新加载配置数据

修改 TestController :

[Route("api/[controller]/[action]")] [ApiController] public class TestController : ControllerBase { private readonly IOptionsSnapshot<MyOptions> _options; public TestController(IOptionsSnapshot<MyOptions> options) { _options = options;  }

 public MyOptions Get() { return _options.Value; }
 }

第一次请求:

修改 json 文件后,刷新页面

通过别名配置选项

 public void ConfigureServices(IServiceCollection services) { services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_2); services.Configure<MyOptions>("option1", Configuration); services.Configure<MyOptions>("option2", options => { options.Id = 6; options.Name = "refuge6"; }); }

修改 TestController

 [Route("api/[controller]/[action]")] [ApiController] public class TestController : ControllerBase { private readonly IOptionsSnapshot<MyOptions> _options; public TestController(IOptionsSnapshot<MyOptions> options) { _options = options; } public IEnumerable<MyOptions> Get() { for (int i = 1; i < 3; i++) { yield return _options.Get("option" + i); } } }