netcore3.0 IOptions 选项（二）

上篇主要介绍IOptions的原理，这篇看下如何使用

定义选项：

public class MyOption
    {
        public string Name { get; set; }
        public int Score { get; set; }
    }

class Program
    {
        static void Main(string[] args)
        {
            var services = new ServiceCollection();
            services.AddOptions();
            services.Configure<MyOption>(option => { option.Name = "Test"; });
            var provider = services.BuildServiceProvider();
            var myOption = provider.GetService<IOptions<MyOption>>();
            Console.WriteLine(myOption.Value.Name);


            Console.Read();

        }
    }

class Program
    {
        static void Main(string[] args)
        {
            var services = new ServiceCollection();
            services.AddOptions();
            services.Configure<MyOption>(option => { option.Name = "Test"; });
            services.PostConfigure<MyOption>(option => { option.Score = 100; });
            var provider = services.BuildServiceProvider();
            var myOption = provider.GetService<IOptions<MyOption>>();
            Console.WriteLine($"{myOption.Value.Name}-{myOption.Value.Score}");


            Console.Read();

        }
    }

public class MyConfigureOptions : IConfigureOptions<MyOption>
    {
        public void Configure(MyOption options)
        {
            options.Name = "abc";
        }
    }

    public class MyConfigureNamedOptions : IConfigureNamedOptions<MyOption>
    {
        public void Configure(MyOption options)
        {
            options.Score = 1000;
        }

        public void Configure(string name, MyOption options)
        {
            if (name == "hello")
            {
                options.Name = "hello";
            }
        }
    }

class Program
    {
        static void Main(string[] args)
        {
            var services = new ServiceCollection();
            services.AddOptions();
            services.AddTransient<A>();
            services.AddTransient<IConfigureOptions<MyOption>>(p => new MyConfigureOptions());
            services.AddTransient<IConfigureOptions<MyOption>>(p => new MyConfigureNamedOptions());
            var provider = services.BuildServiceProvider();
            var myOption = provider.GetService<IOptionsSnapshot<MyOption>>();
            Console.WriteLine($"{myOption.Get("hello").Name}");
            Console.Read();

        }
    }

补充：

选项从IConfiguration中获取

public class NamedConfigureFromConfigurationOptions<TOptions> : ConfigureNamedOptions<TOptions>
        where TOptions : class
    {
        /// <summary>
        /// Constructor that takes the <see cref="IConfiguration"/> instance to bind against.
        /// </summary>
        /// <param name="name">The name of the options instance.</param>
        /// <param name="config">The <see cref="IConfiguration"/> instance.</param>
        public NamedConfigureFromConfigurationOptions(string name, IConfiguration config)
            : this(name, config, _ => { })
        { }

        /// <summary>
        /// Constructor that takes the <see cref="IConfiguration"/> instance to bind against.
        /// </summary>
        /// <param name="name">The name of the options instance.</param>
        /// <param name="config">The <see cref="IConfiguration"/> instance.</param>
        /// <param name="configureBinder">Used to configure the <see cref="BinderOptions"/>.</param>
        public NamedConfigureFromConfigurationOptions(string name, IConfiguration config, Action<BinderOptions> configureBinder)
            : base(name, options => config.Bind(options, configureBinder))
        {
            if (config == null)
            {
                throw new ArgumentNullException(nameof(config));
            }
        }
    }

public class ConfigureFromConfigurationOptions<TOptions> : ConfigureOptions<TOptions>
        where TOptions : class
    {
        /// <summary>
        /// Constructor that takes the <see cref="IConfiguration"/> instance to bind against.
        /// </summary>
        /// <param name="config">The <see cref="IConfiguration"/> instance.</param>
        public ConfigureFromConfigurationOptions(IConfiguration config) 
            : base(options => ConfigurationBinder.Bind(config, options))
        {
            if (config == null)
            {
                throw new ArgumentNullException(nameof(config));
            }
        }
    }

/// <summary>
    /// Extension methods for adding configuration related options services to the DI container.
    /// </summary>
    public static class OptionsConfigurationServiceCollectionExtensions
    {
        /// <summary>
        /// Registers a configuration instance which TOptions will bind against.
        /// </summary>
        /// <typeparam name="TOptions">The type of options being configured.</typeparam>
        /// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param>
        /// <param name="config">The configuration being bound.</param>
        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
        public static IServiceCollection Configure<TOptions>(this IServiceCollection services, IConfiguration config) where TOptions : class
            => services.Configure<TOptions>(Options.Options.DefaultName, config);

        /// <summary>
        /// Registers a configuration instance which TOptions will bind against.
        /// </summary>
        /// <typeparam name="TOptions">The type of options being 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="config">The configuration being bound.</param>
        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
        public static IServiceCollection Configure<TOptions>(this IServiceCollection services, string name, IConfiguration config) where TOptions : class
            => services.Configure<TOptions>(name, config, _ => { });

        /// <summary>
        /// Registers a configuration instance which TOptions will bind against.
        /// </summary>
        /// <typeparam name="TOptions">The type of options being configured.</typeparam>
        /// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param>
        /// <param name="config">The configuration being bound.</param>
        /// <param name="configureBinder">Used to configure the <see cref="BinderOptions"/>.</param>
        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
        public static IServiceCollection Configure<TOptions>(this IServiceCollection services, IConfiguration config, Action<BinderOptions> configureBinder)
            where TOptions : class
            => services.Configure<TOptions>(Options.Options.DefaultName, config, configureBinder);

        /// <summary>
        /// Registers a configuration instance which TOptions will bind against.
        /// </summary>
        /// <typeparam name="TOptions">The type of options being 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="config">The configuration being bound.</param>
        /// <param name="configureBinder">Used to configure the <see cref="BinderOptions"/>.</param>
        /// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
        public static IServiceCollection Configure<TOptions>(this IServiceCollection services, string name, IConfiguration config, Action<BinderOptions> configureBinder)
            where TOptions : class
        {
            if (services == null)
            {
                throw new ArgumentNullException(nameof(services));
            }

            if (config == null)
            {
                throw new ArgumentNullException(nameof(config));
            }

            services.AddOptions();
            services.AddSingleton<IOptionsChangeTokenSource<TOptions>>(new ConfigurationChangeTokenSource<TOptions>(name, config));
            return services.AddSingleton<IConfigureOptions<TOptions>>(new NamedConfigureFromConfigurationOptions<TOptions>(name, config, configureBinder));
        }
    }

从配置文件中获取选项值

class Program
    {
        static void Main(string[] args)
        {
            var configBuilder = new ConfigurationBuilder();
            configBuilder.AddJsonFile("data.json");
            var config = configBuilder.Build();


            var services = new ServiceCollection();
            services.AddOptions();
            services.AddTransient<A>();
            services.Configure<MyOption>(config);
            var provider = services.BuildServiceProvider();
            
            var myOption = provider.GetService<IOptions<MyOption>>();
            Console.WriteLine(myOption.Value.Name);
            Console.Read();

        }
    }