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); ???????????} ???????} ???}当启用多个配置服务时,指定的最后一个配置源优于其他源.
未完待续...
ASP.NET Core 2.2 基础知识(七) 选项模式
原文地址：https://www.cnblogs.com/refuge/p/10226271.html