目录 1、Options模式的用法 2、Options模式源码解析 3、最佳实践 本章将和大家分享ASP.NET Core中Options模式的使用及其源码解析。 在ASP.NET Core中引入了Options这一使用配置方式，其主要是为了
目录
- 1、Options模式的用法
- 2、Options模式源码解析
- 3、最佳实践
本章将和大家分享ASP.NET Core中Options模式的使用及其源码解析。
在ASP.NET Core中引入了Options这一使用配置方式，其主要是为了解决依赖注入时需要传递指定数据问题（不是自行获取，而是能集中配置）。通常来讲我们会把所需要的配置通过IConfiguration对象配置成一个普通的类，并且习惯上我们会把这个类的名字后缀加上Options。所以我们在使用某一个中间件或者使用第三方类库时，经常会看到配置对应的Options代码，例如：关于Cookie的中间件就会配置CookiePolicyOptions这个对象。
1、Options模式的用法
向服务容器中注入TOptions配置（绑定配置）：
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Newtonsoft.Json;
using Newtonsoft.Json.Serialization;
using IConfiguration_IOptions_Demo.Models;
namespace IConfiguration_IOptions_Demo
{
public class Startup
{
public Startup(IConfiguration configuration)
{
Configuration = configuration;
}
public IConfiguration Configuration { get; }
// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
#region Options模式
services.PostConfigureAll<AppSettingsOptions>(options => options.Title = "PostConfigureAll");
services.Configure<AppSettingsOptions>(Configuration);
services.Configure<OtherConfig>(Configuration.GetSection("OtherConfig"));
services.Configure<AppSettingsOptions>(options => options.Title = "Default Name");//默认名称string.Empty
services.Configure<AppSettingsOptions>("FromMemory", options => options.Title = "FromMemory");
services.AddOptions<AppSettingsOptions>("AddOption").Configure(options => options.Title = "AddOptions");
services.Configure<OtherConfig>("FromConfiguration", Configuration.GetSection("OtherConfig"));
services.ConfigureAll<AppSettingsOptions>(options => options.Title = "ConfigureAll");
services.PostConfigure<AppSettingsOptions>(options => options.Title = "PostConfigure");
#endregion Options模式
services
.AddControllersWithViews()
.AddRazorRuntimeCompilation() //修改cshtml后能自动编译
.AddNewtonsoftJson(options =>
{
options.SerializerSettings.ReferenceLoopHandling = ReferenceLoopHandling.Ignore;//忽略循环引用
options.SerializerSettings.NullValueHandling = NullValueHandling.Ignore;//序列化忽略null和空字符串
options.SerializerSettings.MissingMemberHandling = MissingMemberHandling.Ignore;
options.SerializerSettings.ContractResolver = new DefaultContractResolver();//不使用驼峰样式的key
});
// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
if (env.IsDevelopment())
{
app.UseDeveloperExceptionPage();
}
else
app.UseExceptionHandler("/Home/Error");
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();
app.UseEndpoints(endpoints =>
endpoints.MapControllerRoute(
name: "default",
pattern: "{controller=Home}/{action=Index}/{id?}");
});
}
}
从服务容器中获取TOptions对象（读取配置）：
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using IConfiguration_IOptions_Demo.Models;
using Newtonsoft.Json;
using System.Text;
namespace IConfiguration_IOptions_Demo.Controllers
{
public class OptionsDemoController : Controller
{
protected readonly IOptions<AppSettingsOptions> _options; //直接单例，不支持数据变化，性能高
protected readonly IOptionsMonitor<AppSettingsOptions> _optionsMonitor; //支持数据修改，靠的是监听文件更新(onchange)数据（修改配置文件会更新缓存）
protected readonly IOptionsSnapshot<AppSettingsOptions> _optionsSnapshot; //一次请求数据不变的，但是不同请求可以不同的，每次生成
protected readonly IOptions<OtherConfig> _optionsOtherConfig;
public OptionsDemoController(
IOptions<AppSettingsOptions> options,
IOptionsMonitor<AppSettingsOptions> optionsMonitor,
IOptionsSnapshot<AppSettingsOptions> optionsSnapshot,
IOptions<OtherConfig> optionsOtherConfig)
{
_options = options;
_optionsMonitor = optionsMonitor;
_optionsSnapshot = optionsSnapshot;
_optionsOtherConfig = optionsOtherConfig;
}
public IActionResult Index()
var sb = new StringBuilder();
AppSettingsOptions options1 = _options.Value;
OtherConfig otherConfigOptions1 = _optionsOtherConfig.Value;
sb.AppendLine($"_options.Value => {JsonConvert.SerializeObject(options1)}");
sb.AppendLine("");
sb.AppendLine($"_optionsOtherConfig.Value => {JsonConvert.SerializeObject(otherConfigOptions1)}");
AppSettingsOptions options2 = _optionsMonitor.CurrentValue; //_optionsMonitor.Get(Microsoft.Extensions.Options.Options.DefaultName);
AppSettingsOptions fromMemoryOptions2 = _optionsMonitor.Get("FromMemory"); //命名选项
sb.AppendLine($"_optionsMonitor.CurrentValue => {JsonConvert.SerializeObject(options2)}");
sb.AppendLine($"_optionsMonitor.Get(\"FromMemory\") => {JsonConvert.SerializeObject(fromMemoryOptions2)}");
AppSettingsOptions options3 = _optionsSnapshot.Value; //_optionsSnapshot.Get(Microsoft.Extensions.Options.Options.DefaultName);
AppSettingsOptions fromMemoryOptions3 = _optionsSnapshot.Get("FromMemory"); //命名选项
sb.AppendLine($"_optionsSnapshot.Value => {JsonConvert.SerializeObject(options3)}");
sb.AppendLine($"_optionsSnapshot.Get(\"FromMemory\") => {JsonConvert.SerializeObject(fromMemoryOptions3)}");
return Content(sb.ToString());
}
}
访问 “/OptionsDemo/Index” 运行结果如下所示：
2、Options模式源码解析
我们从下面的这条语句开始分析：
services.Configure<AppSettingsOptions>(options => options.Title = "Default Name");
将光标移动到Configure 然后按 F12 转到定义，如下：
可以发现此Configure 是个扩展方法，位于OptionsServiceCollectionExtensions 类中，我们找到OptionsServiceCollectionExtensions 类的源码如下：
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;
using Microsoft.Extensions.DependencyInjection.Extensions;
using Microsoft.Extensions.Options;
namespace Microsoft.Extensions.DependencyInjection
{
/// <summary>
/// Extension methods for adding options services to the DI container.
/// </summary>
public static class OptionsServiceCollectionExtensions
{
/// <summary>
/// Adds services required for using options.
/// </summary>
/// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param>
/// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
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;
}
/// Registers an action used to configure a particular type of options.
/// Note: These are run before all <seealso cref="PostConfigure{TOptions}(IServiceCollection, Action{TOptions})"/>.
/// <typeparam name="TOptions">The options type to be configured.</typeparam>
/// <param name="configureOptions">The action used to configure the options.</param>
public static IServiceCollection Configure<TOptions>(this IServiceCollection services, Action<TOptions> configureOptions) where TOptions : class
=> services.Configure(Options.Options.DefaultName, configureOptions);
/// <param name="name">The name of the options instance.</param>
public static IServiceCollection Configure<TOptions>(this IServiceCollection services, string name, Action<TOptions> configureOptions)
where TOptions : class
if (configureOptions == null)
throw new ArgumentNullException(nameof(configureOptions));
services.AddOptions();
services.AddSingleton<IConfigureOptions<TOptions>>(new ConfigureNamedOptions<TOptions>(name, configureOptions));
/// Registers an action used to configure all instances of a particular type of options.
public static IServiceCollection ConfigureAll<TOptions>(this IServiceCollection services, Action<TOptions> configureOptions) where TOptions : class
=> services.Configure(name: null, configureOptions: configureOptions);
/// Registers an action used to initialize a particular type of options.
/// Note: These are run after all <seealso cref="Configure{TOptions}(IServiceCollection, Action{TOptions})"/>.
public static IServiceCollection PostConfigure<TOptions>(this IServiceCollection services, Action<TOptions> configureOptions) where TOptions : class
=> services.PostConfigure(Options.Options.DefaultName, configureOptions);
/// <typeparam name="TOptions">The options type to be configure.</typeparam>
public static IServiceCollection PostConfigure<TOptions>(this IServiceCollection services, string name, Action<TOptions> configureOptions)
services.AddSingleton<IPostConfigureOptions<TOptions>>(new PostConfigureOptions<TOptions>(name, configureOptions));
/// Registers an action used to post configure all instances of a particular type of options.
public static IServiceCollection PostConfigureAll<TOptions>(this IServiceCollection services, Action<TOptions> configureOptions) where TOptions : class
=> services.PostConfigure(name: null, configureOptions: configureOptions);
/// Registers a type that will have all of its I[Post]ConfigureOptions registered.
/// <typeparam name="TConfigureOptions">The type that will configure options.</typeparam>
public static IServiceCollection ConfigureOptions<TConfigureOptions>(this IServiceCollection services) where TConfigureOptions : class
=> services.ConfigureOptions(typeof(TConfigureOptions));
private static bool IsAction(Type type)
=> (type.GetTypeInfo().IsGenericType && type.GetGenericTypeDefinition() == typeof(Action<>));
private static IEnumerable<Type> FindIConfigureOptions(Type type)
var serviceTypes = type.GetTypeInfo().ImplementedInterfaces
.Where(t => t.GetTypeInfo().IsGenericType &&
(t.GetGenericTypeDefinition() == typeof(IConfigureOptions<>)
|| t.GetGenericTypeDefinition() == typeof(IPostConfigureOptions<>)));
if (!serviceTypes.Any())
throw new InvalidOperationException(
IsAction(type)
? Resources.Error_NoIConfigureOptionsAndAction
: Resources.Error_NoIConfigureOptions);
return serviceTypes;
/// <param name="configureType">The type that will configure options.</param>
public static IServiceCollection ConfigureOptions(this IServiceCollection services, Type configureType)
var serviceTypes = FindIConfigureOptions(configureType);
foreach (var serviceType in serviceTypes)
services.AddTransient(serviceType, configureType);
/// Registers an object that will have all of its I[Post]ConfigureOptions registered.
/// <param name="configureInstance">The instance that will configure options.</param>
public static IServiceCollection ConfigureOptions(this IServiceCollection services, object configureInstance)
var serviceTypes = FindIConfigureOptions(configureInstance.GetType());
services.AddSingleton(serviceType, configureInstance);
/// Gets an options builder that forwards Configure calls for the same <typeparamref name="TOptions"/> to the underlying service collection.
/// <returns>The <see cref="OptionsBuilder{TOptions}"/> so that configure calls can be chained in it.</returns>
public static OptionsBuilder<TOptions> AddOptions<TOptions>(this IServiceCollection services) where TOptions : class
=> services.AddOptions<TOptions>(Options.Options.DefaultName);
/// Gets an options builder that forwards Configure calls for the same named <typeparamref name="TOptions"/> to the underlying service collection.
public static OptionsBuilder<TOptions> AddOptions<TOptions>(this IServiceCollection services, string name)
return new OptionsBuilder<TOptions>(services, name);
}
}
Microsoft.Extensions.DependencyInjection.OptionsServiceCollectionExtensions类源码
仔细阅读上面的源码后可以发现，Configure方法虽然有多个重载，但最终都会调用下面的这个方法：
/// <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;
}
Configure方法的多个重载主要差异在于name参数值的不同。当不传递name参数值时，默认使用Microsoft.Extensions.Options.Options.DefaultName，它等于string.Empty，如下所示：
/// <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);
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
namespace Microsoft.Extensions.Options
{
/// <summary>
/// Helper class.
/// </summary>
public static class Options
{
/// <summary>
/// The default name used for options instances: "".
/// </summary>
public static readonly string DefaultName = string.Empty;
/// Creates a wrapper around an instance of <typeparamref name="TOptions"/> to return itself as an <see cref="IOptions{TOptions}"/>.
/// <typeparam name="TOptions">Options type.</typeparam>
/// <param name="options">Options object.</param>
/// <returns>Wrapped options object.</returns>
public static IOptions<TOptions> Create<TOptions>(TOptions options) where TOptions : class, new()
{
return new OptionsWrapper<TOptions>(options);
}
}
}
另外，我们可以看到ConfigureAll这个方法，此方法的内部也是调用Configure方法，只不过把name值设置成null，后续在创建TOptions时，会把name值为null的Action<TOptions>应用于所有实例。如下：
/// <summary>
/// Registers an action used to configure all instances of a particular type of options.
/// </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 ConfigureAll<TOptions>(this IServiceCollection services, Action<TOptions> configureOptions) where TOptions : class
=> services.Configure(name: null, configureOptions: configureOptions);
至此我们大概知道了，其实Configure方法主要就是做两件事：
1、调用services.AddOptions()方法。
2、将 new ConfigureNamedOptions<TOptions>(name, configureOptions) 注册给IConfigureOptions<TOptions> 。
此外，从OptionsServiceCollectionExtensions类的源码中我们可以发现PostConfigure方法同样有多个重载，并且最终都会调用下面的这个方法：
/// <summary>
/// Registers an action used to configure a particular type of options.
/// Note: These are run after all <seealso cref="Configure{TOptions}(IServiceCollection, Action{TOptions})"/>.
/// </summary>
/// <typeparam name="TOptions">The options type to be configure.</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 PostConfigure<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<IPostConfigureOptions<TOptions>>(new PostConfigureOptions<TOptions>(name, configureOptions));
return services;
}
与Configure方法一样，PostConfigure方法的多个重载主要差异在于name参数值的不同。当不传递name参数值时，默认使用Microsoft.Extensions.Options.Options.DefaultName，它等于string.Empty，如下：
/// <summary>
/// Registers an action used to initialize a particular type of options.
/// Note: These are run after all <seealso cref="Configure{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 PostConfigure<TOptions>(this IServiceCollection services, Action<TOptions> configureOptions) where TOptions : class
=> services.PostConfigure(Options.Options.DefaultName, configureOptions);
同样的，PostConfigureAll方法的内部也是调用PostConfigure方法，只不过把name值设置成null，如下：
/// <summary>
/// Registers an action used to post configure all instances of a particular type of options.
/// Note: These are run after all <seealso cref="Configure{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 PostConfigureAll<TOptions>(this IServiceCollection services, Action<TOptions> configureOptions) where TOptions : class
=> services.PostConfigure(name: null, configureOptions: configureOptions);
至此我们可以发现，PostConfigure方法同样也是只做两件事：
1、调用services.AddOptions() 方法。
2、将new PostConfigureOptions<TOptions>(name, configureOptions) 注册给IPostConfigureOptions<TOptions> 。
其实PostConfigure方法，它和Configure方法使用方式一模一样，也是在创建TOptions时调用。只不过先后顺序不一样，PostConfigure在Configure之后调用，该点在后面的讲解中会再次提到。
另外，还有一种AddOptions的用法，如下所示：
services.AddOptions<AppSettingsOptions>("AddOption").Configure(options => options.Title = "AddOptions");
/// <summary>
/// Gets an options builder that forwards Configure calls for the same <typeparamref name="TOptions"/> to the underlying service collection.
/// </summary>
/// <typeparam name="TOptions">The options type to be configured.</typeparam>
/// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param>
/// <returns>The <see cref="OptionsBuilder{TOptions}"/> so that configure calls can be chained in it.</returns>
public static OptionsBuilder<TOptions> AddOptions<TOptions>(this IServiceCollection services) where TOptions : class
=> services.AddOptions<TOptions>(Options.Options.DefaultName);
/// Gets an options builder that forwards Configure calls for the same named <typeparamref name="TOptions"/> to the underlying service collection.
/// <param name="name">The name of the options instance.</param>
public static OptionsBuilder<TOptions> AddOptions<TOptions>(this IServiceCollection services, string name)
where TOptions : class
{
if (services == null)
{
throw new ArgumentNullException(nameof(services));
}
services.AddOptions();
return new OptionsBuilder<TOptions>(services, name);
}
这种方式会创建一个OptionsBuilder对象，用来辅助配置TOptions对象，我们找到OptionsBuilder类的源码如下：
Microsoft.Extensions.Options.OptionsBuilder类源码
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using Microsoft.Extensions.DependencyInjection;
namespace Microsoft.Extensions.Options
{
/// <summary>
/// Used to configure <typeparamref name="TOptions"/> instances.
/// </summary>
/// <typeparam name="TOptions">The type of options being requested.</typeparam>
public class OptionsBuilder<TOptions> where TOptions : class
{
private const string DefaultValidationFailureMessage = "A validation error has occured.";
/// <summary>
/// The default name of the <typeparamref name="TOptions"/> instance.
/// </summary>
public string Name { get; }
/// The <see cref="IServiceCollection"/> for the options being configured.
public IServiceCollection Services { get; }
/// Constructor.
/// <param name="services">The <see cref="IServiceCollection"/> for the options being configured.</param>
/// <param name="name">The default name of the <typeparamref name="TOptions"/> instance, if null <see cref="Options.DefaultName"/> is used.</param>
public OptionsBuilder(IServiceCollection services, string name)
{
if (services == null)
{
throw new ArgumentNullException(nameof(services));
}
Services = services;
Name = name ?? Options.DefaultName;
}
/// Registers an action used to configure a particular type of options.
/// Note: These are run before all <seealso cref="PostConfigure(Action{TOptions})"/>.
/// <param name="configureOptions">The action used to configure the options.</param>
/// <returns>The current <see cref="OptionsBuilder{TOptions}"/>.</returns>
public virtual OptionsBuilder<TOptions> Configure(Action<TOptions> configureOptions)
if (configureOptions == null)
throw new ArgumentNullException(nameof(configureOptions));
Services.AddSingleton<IConfigureOptions<TOptions>>(new ConfigureNamedOptions<TOptions>(Name, configureOptions));
return this;
/// <typeparam name="TDep">A dependency used by the action.</typeparam>
public virtual OptionsBuilder<TOptions> Configure<TDep>(Action<TOptions, TDep> configureOptions)
where TDep : class
Services.AddTransient<IConfigureOptions<TOptions>>(sp =>
new ConfigureNamedOptions<TOptions, TDep>(Name, sp.GetRequiredService<TDep>(), configureOptions));
/// <typeparam name="TDep1">The first dependency used by the action.</typeparam>
/// <typeparam name="TDep2">The second dependency used by the action.</typeparam>
public virtual OptionsBuilder<TOptions> Configure<TDep1, TDep2>(Action<TOptions, TDep1, TDep2> configureOptions)
where TDep1 : class
where TDep2 : class
new ConfigureNamedOptions<TOptions, TDep1, TDep2>(Name, sp.GetRequiredService<TDep1>(), sp.GetRequiredService<TDep2>(), configureOptions));
/// <typeparam name="TDep3">The third dependency used by the action.</typeparam>
public virtual OptionsBuilder<TOptions> Configure<TDep1, TDep2, TDep3>(Action<TOptions, TDep1, TDep2, TDep3> configureOptions)
where TDep3 : class
Services.AddTransient<IConfigureOptions<TOptions>>(
sp => new ConfigureNamedOptions<TOptions, TDep1, TDep2, TDep3>(
Name,
sp.GetRequiredService<TDep1>(),
sp.GetRequiredService<TDep2>(),
sp.GetRequiredService<TDep3>(),
configureOptions));
/// <typeparam name="TDep4">The fourth dependency used by the action.</typeparam>
public virtual OptionsBuilder<TOptions> Configure<TDep1, TDep2, TDep3, TDep4>(Action<TOptions, TDep1, TDep2, TDep3, TDep4> configureOptions)
where TDep4 : class
sp => new ConfigureNamedOptions<TOptions, TDep1, TDep2, TDep3, TDep4>(
sp.GetRequiredService<TDep4>(),
/// <typeparam name="TDep5">The fifth dependency used by the action.</typeparam>
public virtual OptionsBuilder<TOptions> Configure<TDep1, TDep2, TDep3, TDep4, TDep5>(Action<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5> configureOptions)
where TDep5 : class
sp => new ConfigureNamedOptions<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5>(
sp.GetRequiredService<TDep5>(),
/// Note: These are run after all <seealso cref="Configure(Action{TOptions})"/>.
public virtual OptionsBuilder<TOptions> PostConfigure(Action<TOptions> configureOptions)
Services.AddSingleton<IPostConfigureOptions<TOptions>>(new PostConfigureOptions<TOptions>(Name, configureOptions));
/// Registers an action used to post configure a particular type of options.
/// <typeparam name="TDep">The dependency used by the action.</typeparam>
public virtual OptionsBuilder<TOptions> PostConfigure<TDep>(Action<TOptions, TDep> configureOptions)
Services.AddTransient<IPostConfigureOptions<TOptions>>(sp =>
new PostConfigureOptions<TOptions, TDep>(Name, sp.GetRequiredService<TDep>(), configureOptions));
public virtual OptionsBuilder<TOptions> PostConfigure<TDep1, TDep2>(Action<TOptions, TDep1, TDep2> configureOptions)
new PostConfigureOptions<TOptions, TDep1, TDep2>(Name, sp.GetRequiredService<TDep1>(), sp.GetRequiredService<TDep2>(), configureOptions));
public virtual OptionsBuilder<TOptions> PostConfigure<TDep1, TDep2, TDep3>(Action<TOptions, TDep1, TDep2, TDep3> configureOptions)
Services.AddTransient<IPostConfigureOptions<TOptions>>(
sp => new PostConfigureOptions<TOptions, TDep1, TDep2, TDep3>(
public virtual OptionsBuilder<TOptions> PostConfigure<TDep1, TDep2, TDep3, TDep4>(Action<TOptions, TDep1, TDep2, TDep3, TDep4> configureOptions)
sp => new PostConfigureOptions<TOptions, TDep1, TDep2, TDep3, TDep4>(
public virtual OptionsBuilder<TOptions> PostConfigure<TDep1, TDep2, TDep3, TDep4, TDep5>(Action<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5> configureOptions)
sp => new PostConfigureOptions<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5>(
/// Register a validation action for an options type using a default failure message.
/// <param name="validation">The validation function.</param>
public virtual OptionsBuilder<TOptions> Validate(Func<TOptions, bool> validation)
=> Validate(validation: validation, failureMessage: DefaultValidationFailureMessage);
/// Register a validation action for an options type.
/// <param name="failureMessage">The failure message to use when validation fails.</param>
public virtual OptionsBuilder<TOptions> Validate(Func<TOptions, bool> validation, string failureMessage)
if (validation == null)
throw new ArgumentNullException(nameof(validation));
Services.AddSingleton<IValidateOptions<TOptions>>(new ValidateOptions<TOptions>(Name, validation, failureMessage));
/// <typeparam name="TDep">The dependency used by the validation function.</typeparam>
public virtual OptionsBuilder<TOptions> Validate<TDep>(Func<TOptions, TDep, bool> validation)
public virtual OptionsBuilder<TOptions> Validate<TDep>(Func<TOptions, TDep, bool> validation, string failureMessage)
Services.AddTransient<IValidateOptions<TOptions>>(sp =>
new ValidateOptions<TOptions, TDep>(Name, sp.GetRequiredService<TDep>(), validation, failureMessage));
/// <typeparam name="TDep1">The first dependency used by the validation function.</typeparam>
/// <typeparam name="TDep2">The second dependency used by the validation function.</typeparam>
public virtual OptionsBuilder<TOptions> Validate<TDep1, TDep2>(Func<TOptions, TDep1, TDep2, bool> validation)
public virtual OptionsBuilder<TOptions> Validate<TDep1, TDep2>(Func<TOptions, TDep1, TDep2, bool> validation, string failureMessage)
new ValidateOptions<TOptions, TDep1, TDep2>(Name,
validation,
failureMessage));
/// <typeparam name="TDep3">The third dependency used by the validation function.</typeparam>
public virtual OptionsBuilder<TOptions> Validate<TDep1, TDep2, TDep3>(Func<TOptions, TDep1, TDep2, TDep3, bool> validation)
public virtual OptionsBuilder<TOptions> Validate<TDep1, TDep2, TDep3>(Func<TOptions, TDep1, TDep2, TDep3, bool> validation, string failureMessage)
new ValidateOptions<TOptions, TDep1, TDep2, TDep3>(Name,
/// <typeparam name="TDep4">The fourth dependency used by the validation function.</typeparam>
public virtual OptionsBuilder<TOptions> Validate<TDep1, TDep2, TDep3, TDep4>(Func<TOptions, TDep1, TDep2, TDep3, TDep4, bool> validation)
public virtual OptionsBuilder<TOptions> Validate<TDep1, TDep2, TDep3, TDep4>(Func<TOptions, TDep1, TDep2, TDep3, TDep4, bool> validation, string failureMessage)
new ValidateOptions<TOptions, TDep1, TDep2, TDep3, TDep4>(Name,
/// <typeparam name="TDep5">The fifth dependency used by the validation function.</typeparam>
public virtual OptionsBuilder<TOptions> Validate<TDep1, TDep2, TDep3, TDep4, TDep5>(Func<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5, bool> validation)
public virtual OptionsBuilder<TOptions> Validate<TDep1, TDep2, TDep3, TDep4, TDep5>(Func<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5, bool> validation, string failureMessage)
new ValidateOptions<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5>(Name,
}
}
Microsoft.Extensions.Options.OptionsBuilder类源码
我们重点来看其中的一个方法，如下所示：
/// <summary>
/// Registers an action used to configure a particular type of options.
/// Note: These are run before all <seealso cref="PostConfigure(Action{TOptions})"/>.
/// </summary>
/// <param name="configureOptions">The action used to configure the options.</param>
/// <returns>The current <see cref="OptionsBuilder{TOptions}"/>.</returns>
public virtual OptionsBuilder<TOptions> Configure(Action<TOptions> configureOptions)
{
if (configureOptions == null)
{
throw new ArgumentNullException(nameof(configureOptions));
}
Services.AddSingleton<IConfigureOptions<TOptions>>(new ConfigureNamedOptions<TOptions>(Name, configureOptions));
return this;
}
可以发现其内部实现是和Configure方法一样的。
最后还有一种比较酷的用法，就是在调用Configure方法时并没有传递Action<TOptions>，而是直接传递了一个IConfiguration，如下所示：
services.Configure<AppSettingsOptions>(Configuration);
services.Configure<OtherConfig>(Configuration.GetSection("OtherConfig"));
services.Configure<OtherConfig>("FromConfiguration", Configuration.GetSection("OtherConfig"));
其实这是因为框架在内部帮我们转化了一下，最终传递的还是一个Action<TOptions>，下面我们就重点来看一下这个过程：
我们将光标移动到对应的 Configure 然后按 F12 转到定义，如下所示：
可以发现此Configure 是个扩展方法，位于OptionsConfigurationServiceCollectionExtensions 类中，我们找到OptionsConfigurationServiceCollectionExtensions类的源码如下：
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.Options;
namespace Microsoft.Extensions.DependencyInjection
{
/// <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);
/// <param name="name">The name of the options instance.</param>
public static IServiceCollection Configure<TOptions>(this IServiceCollection services, string name, IConfiguration config) where TOptions : class
=> services.Configure<TOptions>(name, config, _ => { });
/// <param name="configureBinder">Used to configure the <see cref="BinderOptions"/>.</param>
public static IServiceCollection Configure<TOptions>(this IServiceCollection services, IConfiguration config, Action<BinderOptions> configureBinder)
where TOptions : class
=> services.Configure<TOptions>(Options.Options.DefaultName, config, configureBinder);
public static IServiceCollection Configure<TOptions>(this IServiceCollection services, string name, IConfiguration config, Action<BinderOptions> configureBinder)
{
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));
}
}
}
从此处我们可以看出最终它会将new NamedConfigureFromConfigurationOptions<TOptions>(name, config, configureBinder) 注册给IConfigureOptions<TOptions>，我们找到NamedConfigureFromConfigurationOptions 类的源码，如下：
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using Microsoft.Extensions.Configuration;
namespace Microsoft.Extensions.Options
{
/// <summary>
/// Configures an option instance by using <see cref="ConfigurationBinder.Bind(IConfiguration, object)"/> against an <see cref="IConfiguration"/>.
/// </summary>
/// <typeparam name="TOptions">The type of options to bind.</typeparam>
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, _ => { })
{ }
/// <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));
}
}
}
}
从中我们可以发现其实NamedConfigureFromConfigurationOptions<TOptions> 类它是继承自ConfigureNamedOptions<TOptions> 类的，我们继续找到ConfigureNamedOptions<TOptions> 类的源码，如下：
Microsoft.Extensions.Options.ConfigureNamedOptions类源码
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
namespace Microsoft.Extensions.Options
{
/// <summary>
/// Implementation of <see cref="IConfigureNamedOptions{TOptions}"/>.
/// </summary>
/// <typeparam name="TOptions">Options type being configured.</typeparam>
public class ConfigureNamedOptions<TOptions> : IConfigureNamedOptions<TOptions> where TOptions : class
{
/// <summary>
/// Constructor.
/// </summary>
/// <param name="name">The name of the options.</param>
/// <param name="action">The action to register.</param>
public ConfigureNamedOptions(string name, Action<TOptions> action)
{
Name = name;
Action = action;
}
/// The options name.
public string Name { get; }
/// The configuration action.
public Action<TOptions> Action { get; }
/// Invokes the registered configure <see cref="Action"/> if the <paramref name="name"/> matches.
/// <param name="name">The name of the options instance being configured.</param>
/// <param name="options">The options instance to configure.</param>
public virtual void Configure(string name, TOptions options)
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
// Null name is used to configure all named options.
if (Name == null || name == Name)
Action?.Invoke(options);
/// Invoked to configure a <typeparamref name="TOptions"/> instance with the <see cref="Options.DefaultName"/>.
public void Configure(TOptions options) => Configure(Options.DefaultName, options);
}
/// <typeparam name="TDep">Dependency type.</typeparam>
public class ConfigureNamedOptions<TOptions, TDep> : IConfigureNamedOptions<TOptions>
where TOptions : class
where TDep : class
/// <param name="dependency">A dependency.</param>
public ConfigureNamedOptions(string name, TDep dependency, Action<TOptions, TDep> action)
Dependency = dependency;
public Action<TOptions, TDep> Action { get; }
/// The dependency.
public TDep Dependency { get; }
Action?.Invoke(options, Dependency);
/// <typeparam name="TDep1">First dependency type.</typeparam>
/// <typeparam name="TDep2">Second dependency type.</typeparam>
public class ConfigureNamedOptions<TOptions, TDep1, TDep2> : IConfigureNamedOptions<TOptions>
where TDep1 : class
where TDep2 : class
/// <param name="dependency2">A second dependency.</param>
public ConfigureNamedOptions(string name, TDep1 dependency, TDep2 dependency2, Action<TOptions, TDep1, TDep2> action)
Dependency1 = dependency;
Dependency2 = dependency2;
public Action<TOptions, TDep1, TDep2> Action { get; }
/// The first dependency.
public TDep1 Dependency1 { get; }
/// The second dependency.
public TDep2 Dependency2 { get; }
Action?.Invoke(options, Dependency1, Dependency2);
/// <typeparam name="TDep3">Third dependency type.</typeparam>
public class ConfigureNamedOptions<TOptions, TDep1, TDep2, TDep3> : IConfigureNamedOptions<TOptions>
where TDep3 : class
/// <param name="dependency3">A third dependency.</param>
public ConfigureNamedOptions(string name, TDep1 dependency, TDep2 dependency2, TDep3 dependency3, Action<TOptions, TDep1, TDep2, TDep3> action)
Dependency3 = dependency3;
public Action<TOptions, TDep1, TDep2, TDep3> Action { get; }
/// The third dependency.
public TDep3 Dependency3 { get; }
Action?.Invoke(options, Dependency1, Dependency2, Dependency3);
/// <typeparam name="TDep4">Fourth dependency type.</typeparam>
public class ConfigureNamedOptions<TOptions, TDep1, TDep2, TDep3, TDep4> : IConfigureNamedOptions<TOptions>
where TDep4 : class
/// <param name="dependency1">A dependency.</param>
/// <param name="dependency4">A fourth dependency.</param>
public ConfigureNamedOptions(string name, TDep1 dependency1, TDep2 dependency2, TDep3 dependency3, TDep4 dependency4, Action<TOptions, TDep1, TDep2, TDep3, TDep4> action)
Dependency1 = dependency1;
Dependency4 = dependency4;
public Action<TOptions, TDep1, TDep2, TDep3, TDep4> Action { get; }
/// The fourth dependency.
public TDep4 Dependency4 { get; }
Action?.Invoke(options, Dependency1, Dependency2, Dependency3, Dependency4);
/// <typeparam name="TDep5">Fifth dependency type.</typeparam>
public class ConfigureNamedOptions<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5> : IConfigureNamedOptions<TOptions>
where TDep5 : class
/// <param name="dependency5">A fifth dependency.</param>
public ConfigureNamedOptions(string name, TDep1 dependency1, TDep2 dependency2, TDep3 dependency3, TDep4 dependency4, TDep5 dependency5, Action<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5> action)
Dependency5 = dependency5;
public Action<TOptions, TDep1, TDep2, TDep3, TDep4, TDep5> Action { get; }
/// The fifth dependency.
public TDep5 Dependency5 { get; }
Action?.Invoke(options, Dependency1, Dependency2, Dependency3, Dependency4, Dependency5);
}
Microsoft.Extensions.Options.ConfigureNamedOptions类源码
其中我们重点来看下面的这部分：
/// <summary>
/// Implementation of <see cref="IConfigureNamedOptions{TOptions}"/>.
/// </summary>
/// <typeparam name="TOptions">Options type being configured.</typeparam>
public class ConfigureNamedOptions<TOptions> : IConfigureNamedOptions<TOptions> where TOptions : class
{
/// <summary>
/// Constructor.
/// </summary>
/// <param name="name">The name of the options.</param>
/// <param name="action">The action to register.</param>
public ConfigureNamedOptions(string name, Action<TOptions> action)
{
Name = name;
Action = action;
}
/// The options name.
public string Name { get; }
/// The configuration action.
public Action<TOptions> Action { get; }
/// Invokes the registered configure <see cref="Action"/> if the <paramref name="name"/> matches.
/// <param name="name">The name of the options instance being configured.</param>
/// <param name="options">The options instance to configure.</param>
public virtual void Configure(string name, TOptions options)
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
// Null name is used to configure all named options.
if (Name == null || name == Name)
Action?.Invoke(options);
/// Invoked to configure a <typeparamref name="TOptions"/> instance with the <see cref="Options.DefaultName"/>.
public void Configure(TOptions options) => Configure(Options.DefaultName, options);
}
结合NamedConfigureFromConfigurationOptions<TOptions> 和ConfigureNamedOptions<TOptions> 这两个类的源码我们可以发现：
1、 调用 services.Configure<AppSettingsOptions>(Configuration) 方法时框架在内部帮我们转化了一下，最终传递的是 “options => config.Bind(options, configureBinder)” 。
2、 调用 Configure(string name, TOptions options) 方法时会把Name值为null的Action<TOptions>应用于所有TOptions实例。
我们找到config.Bind(options, configureBinder) 这个方法，它是个扩展方法，位于ConfigurationBinder静态类中，如下：
Microsoft.Extensions.Configuration.ConfigurationBinder类源码
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Reflection;
using Microsoft.Extensions.Configuration.Binder;
namespace Microsoft.Extensions.Configuration
{
/// <summary>
/// Static helper class that allows binding strongly typed objects to configuration values.
/// </summary>
public static class ConfigurationBinder
{
/// <summary>
/// Attempts to bind the configuration instance to a new instance of type T.
/// If this configuration section has a value, that will be used.
/// Otherwise binding by matching property names against configuration keys recursively.
/// </summary>
/// <typeparam name="T">The type of the new instance to bind.</typeparam>
/// <param name="configuration">The configuration instance to bind.</param>
/// <returns>The new instance of T if successful, default(T) otherwise.</returns>
public static T Get<T>(this IConfiguration configuration)
=> configuration.Get<T>(_ => { });
/// <param name="configureOptions">Configures the binder options.</param>
public static T Get<T>(this IConfiguration configuration, Action<BinderOptions> configureOptions)
{
if (configuration == null)
{
throw new ArgumentNullException(nameof(configuration));
}
var result = configuration.Get(typeof(T), configureOptions);
if (result == null)
return default(T);
return (T)result;
}
/// <param name="type">The type of the new instance to bind.</param>
/// <returns>The new instance if successful, null otherwise.</returns>
public static object Get(this IConfiguration configuration, Type type)
=> configuration.Get(type, _ => { });
public static object Get(this IConfiguration configuration, Type type, Action<BinderOptions> configureOptions)
var options = new BinderOptions();
configureOptions?.Invoke(options);
return BindInstance(type, instance: null, config: configuration, options: options);
/// Attempts to bind the given object instance to the configuration section specified by the key by matching property names against configuration keys recursively.
/// <param name="key">The key of the configuration section to bind.</param>
/// <param name="instance">The object to bind.</param>
public static void Bind(this IConfiguration configuration, string key, object instance)
=> configuration.GetSection(key).Bind(instance);
/// Attempts to bind the given object instance to configuration values by matching property names against configuration keys recursively.
public static void Bind(this IConfiguration configuration, object instance)
=> configuration.Bind(instance, o => { });
public static void Bind(this IConfiguration configuration, object instance, Action<BinderOptions> configureOptions)
if (instance != null)
var options = new BinderOptions();
configureOptions?.Invoke(options);
BindInstance(instance.GetType(), instance, configuration, options);
/// Extracts the value with the specified key and converts it to type T.
/// <typeparam name="T">The type to convert the value to.</typeparam>
/// <param name="configuration">The configuration.</param>
/// <param name="key">The key of the configuration section's value to convert.</param>
/// <returns>The converted value.</returns>
public static T GetValue<T>(this IConfiguration configuration, string key)
return GetValue(configuration, key, default(T));
/// <param name="defaultValue">The default value to use if no value is found.</param>
public static T GetValue<T>(this IConfiguration configuration, string key, T defaultValue)
return (T)GetValue(configuration, typeof(T), key, defaultValue);
/// Extracts the value with the specified key and converts it to the specified type.
/// <param name="type">The type to convert the value to.</param>
public static object GetValue(this IConfiguration configuration, Type type, string key)
return GetValue(configuration, type, key, defaultValue: null);
public static object GetValue(this IConfiguration configuration, Type type, string key, object defaultValue)
var section = configuration.GetSection(key);
var value = section.Value;
if (value != null)
return ConvertValue(type, value, section.Path);
return defaultValue;
private static void BindNonScalar(this IConfiguration configuration, object instance, BinderOptions options)
foreach (var property in GetAllProperties(instance.GetType().GetTypeInfo()))
{
BindProperty(property, instance, configuration, options);
}
private static void BindProperty(PropertyInfo property, object instance, IConfiguration config, BinderOptions options)
// We don't support set only, non public, or indexer properties
if (property.GetMethod == null ||
(!options.BindNonPublicProperties && !property.GetMethod.IsPublic) ||
property.GetMethod.GetParameters().Length > 0)
return;
var propertyValue = property.GetValue(instance);
var hasSetter = property.SetMethod != null && (property.SetMethod.IsPublic || options.BindNonPublicProperties);
if (propertyValue == null && !hasSetter)
// Property doesn't have a value and we cannot set it so there is no
// point in going further down the graph
propertyValue = BindInstance(property.PropertyType, propertyValue, config.GetSection(property.Name), options);
if (propertyValue != null && hasSetter)
property.SetValue(instance, propertyValue);
private static object BindToCollection(TypeInfo typeInfo, IConfiguration config, BinderOptions options)
var type = typeof(List<>).MakeGenericType(typeInfo.GenericTypeArguments[0]);
var instance = Activator.CreateInstance(type);
BindCollection(instance, type, config, options);
return instance;
// Try to create an array/dictionary instance to back various collection interfaces
private static object AttemptBindToCollectionInterfaces(Type type, IConfiguration config, BinderOptions options)
var typeInfo = type.GetTypeInfo();
if (!typeInfo.IsInterface)
return null;
var collectionInterface = FindOpenGenericInterface(typeof(IReadOnlyList<>), type);
if (collectionInterface != null)
// IEnumerable<T> is guaranteed to have exactly one parameter
return BindToCollection(typeInfo, config, options);
collectionInterface = FindOpenGenericInterface(typeof(IReadOnlyDictionary<,>), type);
var dictionaryType = typeof(Dictionary<,>).MakeGenericType(typeInfo.GenericTypeArguments[0], typeInfo.GenericTypeArguments[1]);
var instance = Activator.CreateInstance(dictionaryType);
BindDictionary(instance, dictionaryType, config, options);
return instance;
collectionInterface = FindOpenGenericInterface(typeof(IDictionary<,>), type);
var instance = Activator.CreateInstance(typeof(Dictionary<,>).MakeGenericType(typeInfo.GenericTypeArguments[0], typeInfo.GenericTypeArguments[1]));
BindDictionary(instance, collectionInterface, config, options);
collectionInterface = FindOpenGenericInterface(typeof(IReadOnlyCollection<>), type);
// IReadOnlyCollection<T> is guaranteed to have exactly one parameter
collectionInterface = FindOpenGenericInterface(typeof(ICollection<>), type);
// ICollection<T> is guaranteed to have exactly one parameter
collectionInterface = FindOpenGenericInterface(typeof(IEnumerable<>), type);
return null;
private static object BindInstance(Type type, object instance, IConfiguration config, BinderOptions options)
// if binding IConfigurationSection, break early
if (type == typeof(IConfigurationSection))
return config;
var section = config as IConfigurationSection;
var configValue = section?.Value;
object convertedValue;
Exception error;
if (configValue != null && TryConvertValue(type, configValue, section.Path, out convertedValue, out error))
if (error != null)
throw error;
// Leaf nodes are always reinitialized
return convertedValue;
if (config != null && config.GetChildren().Any())
// If we don't have an instance, try to create one
if (instance == null)
// We are already done if binding to a new collection instance worked
instance = AttemptBindToCollectionInterfaces(type, config, options);
if (instance != null)
{
return instance;
}
instance = CreateInstance(type);
// See if its a Dictionary
var collectionInterface = FindOpenGenericInterface(typeof(IDictionary<,>), type);
if (collectionInterface != null)
BindDictionary(instance, collectionInterface, config, options);
else if (type.IsArray)
instance = BindArray((Array)instance, config, options);
else
// See if its an ICollection
collectionInterface = FindOpenGenericInterface(typeof(ICollection<>), type);
if (collectionInterface != null)
BindCollection(instance, collectionInterface, config, options);
// Something else
else
BindNonScalar(config, instance, options);
private static object CreateInstance(Type type)
if (typeInfo.IsInterface || typeInfo.IsAbstract)
throw new InvalidOperationException(Resources.FormatError_CannotActivateAbstractOrInterface(type));
if (type.IsArray)
if (typeInfo.GetArrayRank() > 1)
throw new InvalidOperationException(Resources.FormatError_UnsupportedMultidimensionalArray(type));
return Array.CreateInstance(typeInfo.GetElementType(), 0);
var hasDefaultConstructor = typeInfo.DeclaredConstructors.Any(ctor => ctor.IsPublic && ctor.GetParameters().Length == 0);
if (!hasDefaultConstructor)
throw new InvalidOperationException(Resources.FormatError_MissingParameterlessConstructor(type));
try
return Activator.CreateInstance(type);
catch (Exception ex)
throw new InvalidOperationException(Resources.FormatError_FailedToActivate(type), ex);
private static void BindDictionary(object dictionary, Type dictionaryType, IConfiguration config, BinderOptions options)
var typeInfo = dictionaryType.GetTypeInfo();
// IDictionary<K,V> is guaranteed to have exactly two parameters
var keyType = typeInfo.GenericTypeArguments[0];
var valueType = typeInfo.GenericTypeArguments[1];
var keyTypeIsEnum = keyType.GetTypeInfo().IsEnum;
if (keyType != typeof(string) && !keyTypeIsEnum)
// We only support string and enum keys
var setter = typeInfo.GetDeclaredProperty("Item");
foreach (var child in config.GetChildren())
var item = BindInstance(
type: valueType,
instance: null,
config: child,
options: options);
if (item != null)
if (keyType == typeof(string))
var key = child.Key;
setter.SetValue(dictionary, item, new object[] { key });
else if (keyTypeIsEnum)
var key = Enum.Parse(keyType, child.Key);
private static void BindCollection(object collection, Type collectionType, IConfiguration config, BinderOptions options)
var typeInfo = collectionType.GetTypeInfo();
// ICollection<T> is guaranteed to have exactly one parameter
var itemType = typeInfo.GenericTypeArguments[0];
var addMethod = typeInfo.GetDeclaredMethod("Add");
foreach (var section in config.GetChildren())
try
var item = BindInstance(
type: itemType,
instance: null,
config: section,
options: options);
if (item != null)
addMethod.Invoke(collection, new[] { item });
catch
private static Array BindArray(Array source, IConfiguration config, BinderOptions options)
var children = config.GetChildren().ToArray();
var arrayLength = source.Length;
var elementType = source.GetType().GetElementType();
var newArray = Array.CreateInstance(elementType, arrayLength + children.Length);
// binding to array has to preserve already initialized arrays with values
if (arrayLength > 0)
Array.Copy(source, newArray, arrayLength);
for (int i = 0; i < children.Length; i++)
type: elementType,
config: children[i],
newArray.SetValue(item, arrayLength + i);
return newArray;
private static bool TryConvertValue(Type type, string value, string path, out object result, out Exception error)
error = null;
result = null;
if (type == typeof(object))
result = value;
return true;
if (type.GetTypeInfo().IsGenericType && type.GetGenericTypeDefinition() == typeof(Nullable<>))
if (string.IsNullOrEmpty(value))
return true;
return TryConvertValue(Nullable.GetUnderlyingType(type), value, path, out result, out error);
var converter = TypeDescriptor.GetConverter(type);
if (converter.CanConvertFrom(typeof(string)))
result = converter.ConvertFromInvariantString(value);
catch (Exception ex)
error = new InvalidOperationException(Resources.FormatError_FailedBinding(path, type), ex);
return false;
private static object ConvertValue(Type type, string value, string path)
object result;
TryConvertValue(type, value, path, out result, out error);
if (error != null)
throw error;
return result;
private static Type FindOpenGenericInterface(Type expected, Type actual)
var actualTypeInfo = actual.GetTypeInfo();
if(actualTypeInfo.IsGenericType &&
actual.GetGenericTypeDefinition() == expected)
return actual;
var interfaces = actualTypeInfo.ImplementedInterfaces;
foreach (var interfaceType in interfaces)
if (interfaceType.GetTypeInfo().IsGenericType &&
interfaceType.GetGenericTypeDefinition() == expected)
return interfaceType;
private static IEnumerable<PropertyInfo> GetAllProperties(TypeInfo type)
var allProperties = new List<PropertyInfo>();
do
allProperties.AddRange(type.DeclaredProperties);
type = type.BaseType.GetTypeInfo();
while (type != typeof(object).GetTypeInfo());
return allProperties;
}
}
Microsoft.Extensions.Configuration.ConfigurationBinder类源码
仔细阅读上面的源码你会发现，其实它是通过反射的方式为TOptions实例赋值的，而它的值则是通过IConfiguration方式获取的，如果通过IConfiguration方式没有获取到指定的值则不做任何处理还是保留原来的默认值。对于使用IConfiguration获取配置值的实现原理，这在上一篇我们已经详细的讲解过了，此处就不再做过多的介绍了。
从上文的分析中我们可以知道，不管是采用哪种绑定配置的方式其内部都会调用 services.AddOptions() 这个方法，该方法位于OptionsServiceCollectionExtensions静态类中，我们找到该方法，如下所示：
/// <summary>
/// Adds services required for using options.
/// </summary>
/// <param name="services">The <see cref="IServiceCollection"/> to add the services to.</param>
/// <returns>The <see cref="IServiceCollection"/> so that additional calls can be chained.</returns>
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;
}
从中我们大概能猜出 IOptions<TOptions>、IOptionsMonitor<TOptions> 以及 IOptionsSnapshot<TOptions>这三者的主要区别：
1、IOptions在注册到容器时是以单例的形式，这种方式数据全局唯一，不支持数据变化。
2、IOptionsSnapshot在注册到容器时是以Scoped的形式，这种方式单次请求数据是不变的，但是不同的请求数据有可能是不一样的，它能觉察到配置源的改变。
3、IOptionsMonitor在注册到容器时虽然也是以单例的形式，但是它多了一个IOptionsMonitorCache缓存，它也是能觉察到配置源的改变，一旦发生改变就会告知OptionsMonitor从缓存中移除相应的对象。
下面我们继续往下分析，首先找到OptionsManager 类的源码，如下所示：
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
namespace Microsoft.Extensions.Options
{
/// <summary>
/// Implementation of <see cref="IOptions{TOptions}"/> and <see cref="IOptionsSnapshot{TOptions}"/>.
/// </summary>
/// <typeparam name="TOptions">Options type.</typeparam>
public class OptionsManager<TOptions> : IOptions<TOptions>, IOptionsSnapshot<TOptions> where TOptions : class, new()
{
private readonly IOptionsFactory<TOptions> _factory;
private readonly OptionsCache<TOptions> _cache = new OptionsCache<TOptions>(); // Note: this is a private cache
/// <summary>
/// Initializes a new instance with the specified options configurations.
/// </summary>
/// <param name="factory">The factory to use to create options.</param>
public OptionsManager(IOptionsFactory<TOptions> factory)
{
_factory = factory;
}
/// The default configured <typeparamref name="TOptions"/> instance, equivalent to Get(Options.DefaultName).
public TOptions Value
get
{
return Get(Options.DefaultName);
}
/// Returns a configured <typeparamref name="TOptions"/> instance with the given <paramref name="name"/>.
public virtual TOptions Get(string name)
name = name ?? Options.DefaultName;
// Store the options in our instance cache
return _cache.GetOrAdd(name, () => _factory.Create(name));
}
}
可以发现TOptions对象是通过IOptionsFactory工厂产生的，我们继续找到OptionsFactory 类的源码，如下：
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System.Collections.Generic;
namespace Microsoft.Extensions.Options
{
/// <summary>
/// Implementation of <see cref="IOptionsFactory{TOptions}"/>.
/// </summary>
/// <typeparam name="TOptions">The type of options being requested.</typeparam>
public class OptionsFactory<TOptions> : IOptionsFactory<TOptions> where TOptions : class, new()
{
private readonly IEnumerable<IConfigureOptions<TOptions>> _setups;
private readonly IEnumerable<IPostConfigureOptions<TOptions>> _postConfigures;
private readonly IEnumerable<IValidateOptions<TOptions>> _validations;
/// <summary>
/// Initializes a new instance with the specified options configurations.
/// </summary>
/// <param name="setups">The configuration actions to run.</param>
/// <param name="postConfigures">The initialization actions to run.</param>
public OptionsFactory(IEnumerable<IConfigureOptions<TOptions>> setups, IEnumerable<IPostConfigureOptions<TOptions>> postConfigures) : this(setups, postConfigures, validations: null)
{ }
/// <param name="validations">The validations to run.</param>
public OptionsFactory(IEnumerable<IConfigureOptions<TOptions>> setups, IEnumerable<IPostConfigureOptions<TOptions>> postConfigures, IEnumerable<IValidateOptions<TOptions>> validations)
{
_setups = setups;
_postConfigures = postConfigures;
_validations = validations;
}
/// Returns a configured <typeparamref name="TOptions"/> instance with the given <paramref name="name"/>.
public TOptions Create(string name)
var options = new TOptions();
foreach (var setup in _setups)
{
if (setup is IConfigureNamedOptions<TOptions> namedSetup)
{
namedSetup.Configure(name, options);
}
else if (name == Options.DefaultName)
setup.Configure(options);
}
foreach (var post in _postConfigures)
post.PostConfigure(name, options);
if (_validations != null)
var failures = new List<string>();
foreach (var validate in _validations)
var result = validate.Validate(name, options);
if (result.Failed)
{
failures.AddRange(result.Failures);
}
if (failures.Count > 0)
throw new OptionsValidationException(name, typeof(TOptions), failures);
return options;
}
}
从此处我们可以看出，在调用 Create(string name) 方法时，首先它会去先创建一个 TOptions 对象，接着再遍历_setups 集合去依次调用所有的 Configure 方法，最后再遍历 _postConfigures 集合去依次调用所有的 PostConfigure 方法。而从上文的分析中我们知道此时_setups 集合中存放的是 ConfigureNamedOptions<TOptions>类型的对象，_postConfigures集合中存放的则是PostConfigureOptions<TOptions>类型的对象。我们分别找到这两个类的源码，如下所示：
/// <summary>
/// Implementation of <see cref="IConfigureNamedOptions{TOptions}"/>.
/// </summary>
/// <typeparam name="TOptions">Options type being configured.</typeparam>
public class ConfigureNamedOptions<TOptions> : IConfigureNamedOptions<TOptions> where TOptions : class
{
/// <summary>
/// Constructor.
/// </summary>
/// <param name="name">The name of the options.</param>
/// <param name="action">The action to register.</param>
public ConfigureNamedOptions(string name, Action<TOptions> action)
{
Name = name;
Action = action;
}
/// The options name.
public string Name { get; }
/// The configuration action.
public Action<TOptions> Action { get; }
/// Invokes the registered configure <see cref="Action"/> if the <paramref name="name"/> matches.
/// <param name="name">The name of the options instance being configured.</param>
/// <param name="options">The options instance to configure.</param>
public virtual void Configure(string name, TOptions options)
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
// Null name is used to configure all named options.
if (Name == null || name == Name)
Action?.Invoke(options);
/// Invoked to configure a <typeparamref name="TOptions"/> instance with the <see cref="Options.DefaultName"/>.
public void Configure(TOptions options) => Configure(Options.DefaultName, options);
}
/// <summary>
/// Implementation of <see cref="IPostConfigureOptions{TOptions}"/>.
/// </summary>
/// <typeparam name="TOptions">Options type being configured.</typeparam>
public class PostConfigureOptions<TOptions> : IPostConfigureOptions<TOptions> where TOptions : class
{
/// <summary>
/// Creates a new instance of <see cref="PostConfigureOptions{TOptions}"/>.
/// </summary>
/// <param name="name">The name of the options.</param>
/// <param name="action">The action to register.</param>
public PostConfigureOptions(string name, Action<TOptions> action)
{
Name = name;
Action = action;
}
/// The options name.
public string Name { get; }
/// The initialization action.
public Action<TOptions> Action { get; }
/// Invokes the registered initialization <see cref="Action"/> if the <paramref name="name"/> matches.
/// <param name="name">The name of the action to invoke.</param>
/// <param name="options">The options to use in initialization.</param>
public virtual void PostConfigure(string name, TOptions options)
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
// Null name is used to initialize all named options.
if (Name == null || name == Name)
Action?.Invoke(options);
}
至此，我们整个流程都串起来了，最后我们来看下OptionsMonitor 类的源码，如下所示：
// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Collections.Generic;
using Microsoft.Extensions.Primitives;
namespace Microsoft.Extensions.Options
{
/// <summary>
/// Implementation of <see cref="IOptionsMonitor{TOptions}"/>.
/// </summary>
/// <typeparam name="TOptions">Options type.</typeparam>
public class OptionsMonitor<TOptions> : IOptionsMonitor<TOptions>, IDisposable where TOptions : class, new()
{
private readonly IOptionsMonitorCache<TOptions> _cache;
private readonly IOptionsFactory<TOptions> _factory;
private readonly IEnumerable<IOptionsChangeTokenSource<TOptions>> _sources;
private readonly List<IDisposable> _registrations = new List<IDisposable>();
internal event Action<TOptions, string> _onChange;
/// <summary>
/// Constructor.
/// </summary>
/// <param name="factory">The factory to use to create options.</param>
/// <param name="sources">The sources used to listen for changes to the options instance.</param>
/// <param name="cache">The cache used to store options.</param>
public OptionsMonitor(IOptionsFactory<TOptions> factory, IEnumerable<IOptionsChangeTokenSource<TOptions>> sources, IOptionsMonitorCache<TOptions> cache)
{
_factory = factory;
_sources = sources;
_cache = cache;
foreach (var source in _sources)
{
var registration = ChangeToken.OnChange(
() => source.GetChangeToken(),
(name) => InvokeChanged(name),
source.Name);
_registrations.Add(registration);
}
}
private void InvokeChanged(string name)
name = name ?? Options.DefaultName;
_cache.TryRemove(name);
var options = Get(name);
if (_onChange != null)
_onChange.Invoke(options, name);
/// The present value of the options.
public TOptions CurrentValue
get => Get(Options.DefaultName);
/// Returns a configured <typeparamref name="TOptions"/> instance with the given <paramref name="name"/>.
public virtual TOptions Get(string name)
return _cache.GetOrAdd(name, () => _factory.Create(name));
/// Registers a listener to be called whenever <typeparamref name="TOptions"/> changes.
/// <param name="listener">The action to be invoked when <typeparamref name="TOptions"/> has changed.</param>
/// <returns>An <see cref="IDisposable"/> which should be disposed to stop listening for changes.</returns>
public IDisposable OnChange(Action<TOptions, string> listener)
var disposable = new ChangeTrackerDisposable(this, listener);
_onChange += disposable.OnChange;
return disposable;
/// Removes all change registration subscriptions.
public void Dispose()
// Remove all subscriptions to the change tokens
foreach (var registration in _registrations)
registration.Dispose();
_registrations.Clear();
internal class ChangeTrackerDisposable : IDisposable
private readonly Action<TOptions, string> _listener;
private readonly OptionsMonitor<TOptions> _monitor;
public ChangeTrackerDisposable(OptionsMonitor<TOptions> monitor, Action<TOptions, string> listener)
_listener = listener;
_monitor = monitor;
public void OnChange(TOptions options, string name) => _listener.Invoke(options, name);
public void Dispose() => _monitor._onChange -= OnChange;
}
}
Microsoft.Extensions.Options.OptionsMonitor类源码
Microsoft.Extensions.Options.OptionsMonitor类源码
3、最佳实践
既然有如此多的获取方式，那我们应该如何选择呢？
1、如果TOption不需要监控且整个程序就只有一个同类型的TOption，那么强烈建议使用IOptions<TOptions>。
2、如果TOption需要监控或者整个程序有多个同类型的TOption，那么只能选择IOptionsMonitor<TOptions>或者IOptionsSnapshot<TOptions>。
3、当IOptionsMonitor<TOptions>和IOptionsSnapshot<TOptions>都可以选择时，如果Action<TOptions>是一个比较耗时的操作，那么建议使用IOptionsMonitor<TOptions>，反之选择IOptionsSnapshot<TOptions>。
4、如果需要对配置源的更新做出反应时（不仅仅是配置对象TOptions本身的更新），那么只能使用IOptionsMonitor<TOptions>，并且注册回调。
本文部分内容参考博文：https://www.cnblogs.com/zhurongbo/p/10856073.html
选项模式微软官方文档：https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/configuration/options?view=aspnetcore-6.0
aspnetcore源码：
链接: https://pan.baidu.com/s/1BLLjRsvTEBmeVRX68eX7qg?pwd=mju5
提取码: mju5
Demo源码：
链接: https://pan.baidu.com/s/1P9whG1as62gkZEvgz7eSwg?pwd=d6zm
提取码: d6zm
版权声明：如有雷同纯属巧合，如有侵权请及时联系本人修改，谢谢！！！
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