asp.net core选项Options模块的笔记
这篇博客是写给自己看的。已经不止一次看到AddOptions的出现,不管是在.net core源码还是别人的框架里面,都充斥着AddOptions。于是自己大概研究了下,没有深入,因为,我的功力还是不够,等能力到了再回头研究下。在这里还是要说一遍,因为DI的重要性不言而喻,不必谈的太深,说下自己的理解:
DI实现其实很简单,首先设计类来实现接口,而不是把所有的程序逻辑写在一个类文件中,然后我们传入一个接口和一个继承自接口的类作为参数,然后我们在相应的函数那将泛型参数T作为形参,伪代码:
//调用部分
HandleDI<ITest, Test>
//实现部分
HandleDI<TInterface, T>
// 使用反射,EMIT,委托来实例化T创建TInterface的对象
然后我们使用反射或者EMIT或是委托TInterface对象。这就是DI的实现过程。
DI说白了,作用就是 解耦的 实例化继承自接口的类
如果在程序中基于IOptions<TOptions>实现了你自己的选项配置类,最好就是调用AddOptions完成Options的几个重要对象的实例化。
AddOptions:
完成几个重要的Options对象的实例化:
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public static IServiceCollection AddOptions(this IServiceCollection services) { if (services == null) { throw new ArgumentNullException(nameof(services)); } services.TryAdd(ServiceDescriptor.Singleton(typeof(IOptions<>), typeof(OptionsManager<>))); services.TryAdd(ServiceDescriptor.Scoped(typeof(IOptionsSnapshot<>), typeof(OptionsManager<>))); services.TryAdd(ServiceDescriptor.Singleton(typeof(IOptionsMonitor<>), typeof(OptionsMonitor<>))); services.TryAdd(ServiceDescriptor.Transient(typeof(IOptionsFactory<>), typeof(OptionsFactory<>))); services.TryAdd(ServiceDescriptor.Singleton(typeof(IOptionsMonitorCache<>), typeof(OptionsCache<>))); return services; }
Configure: 完成的是TOption类的实例化过程,最终调用AddSingleton做DI。
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/// <summary> /// Registers an action used to configure a particular type of options. /// Note: These are run before all <seealso cref="PostConfigure{TOptions}(IServiceCollection, Action{TOptions})"/>. /// </summary> /// <typeparam name="TOptions">The options type to be configured.</typeparam> /// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param> /// <param name="configureOptions">The action used to configure the options.</param> /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns> public static IServiceCollection Configure<TOptions>(this IServiceCollection services, Action<TOptions> configureOptions) where TOptions : class => services.Configure(Options.Options.DefaultName, configureOptions); /// <summary> /// Registers an action used to configure a particular type of options. /// Note: These are run before all <seealso cref="PostConfigure{TOptions}(IServiceCollection, Action{TOptions})"/>. /// </summary> /// <typeparam name="TOptions">The options type to be configured.</typeparam> /// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param> /// <param name="name">The name of the options instance.</param> /// <param name="configureOptions">The action used to configure the options.</param> /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns> public static IServiceCollection Configure<TOptions>(this IServiceCollection services, string name, Action<TOptions> configureOptions) where TOptions : class { if (services == null) { throw new ArgumentNullException(nameof(services)); } if (configureOptions == null) { throw new ArgumentNullException(nameof(configureOptions)); } services.AddOptions(); services.AddSingleton<IConfigureOptions<TOptions>>(new ConfigureNamedOptions<TOptions>(name, configureOptions)); return services; }
这两个的实现,都是IOC的功劳,如果不去深究其作用,单单就是看代码,其实就是DI的实例化接口类。