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所属分类：.NET技术
为了能够通过配置文件（appsettings.json）或通过代码进行背景图片与模板进行配置、可自定义资源类型、自定义验证规则，本节创建一些扩展类，用来实现这些功能。
上一节内容：NET 6 实现滑动验证码（三）、接口
扩展类都放在了Extensions文件夹下
目录
CaptchaBuilderExtensions.cs
CaptchaBuilderExtensions.cs实现了自定义提供验证码背景图片资源或模板资源、自定义实现资源类型、替换默认验证规则、禁用默认凹槽模板
using SlideCaptcha; using SlideCaptcha.Interface; using SlideCaptcha.Resources.Provider; using System.Linq; namespace Microsoft.Extensions.DependencyInjection { public static class CaptchaBuilderExtensions { /// <summary> /// 自定义提供验证码背景图片资源或模板资源 /// </summary> /// <typeparam name="TProvider">自定义实现</typeparam> /// <param name="builder"></param> /// <returns></returns> public static CaptchaBuilder AddResourceProvider<TProvider>(this CaptchaBuilder builder) where TProvider : class, IResourceProvider { builder.Services.AddSingleton<IResourceProvider, TProvider>(); return builder; } /// <summary> /// 自定义实现资源类型 /// </summary> /// <typeparam name="THandler">自定义实现</typeparam> /// <param name="builder"></param> /// <returns></returns> public static CaptchaBuilder AddResourceHandler<THandler>(this CaptchaBuilder builder) where THandler : class, IResourceHandler { builder.Services.AddSingleton<IResourceHandler, THandler>(); return builder; } /// <summary> /// 替换默认的验证规则 /// </summary> /// <typeparam name="TValidator">自定义验证规则</typeparam> /// <param name="builder"></param> /// <returns></returns> public static CaptchaBuilder ReplaceValidator<TValidator>(this CaptchaBuilder builder) where TValidator : class, IValidator { builder.Services.Replace<IValidator, TValidator>(); return builder; } /// <summary> /// 禁用默认凹槽模板 /// </summary> /// <param name="builder"></param> /// <returns></returns> public static CaptchaBuilder DisableDefaultTemplates(this CaptchaBuilder builder) { var serviceDescriptor = builder.Services.FirstOrDefault(e => e.ImplementationType == typeof(EmbeddedResourceProvider)); if (serviceDescriptor != null) { builder.Services.Remove(serviceDescriptor); } return builder; } } } CaptchaServiceCollectionExtensions.cs
CaptchaServiceCollectionExtensions.cs为自动注入必要的接口
using Microsoft.Extensions.Configuration; using SlideCaptcha; using SlideCaptcha.Constant; using SlideCaptcha.Generator; using SlideCaptcha.Interface; using SlideCaptcha.Resources; using SlideCaptcha.Resources.Handler; using SlideCaptcha.Resources.Provider; using SlideCaptcha.Storage; using SlideCaptcha.Validator; using System; namespace Microsoft.Extensions.DependencyInjection { public static class CaptchaServiceCollectionExtensions { /// <summary> /// 依赖注入必要的接口。 /// </summary> /// <param name="services"></param> /// <param name="configuration"></param> /// <param name="optionsAction"></param> /// <returns></returns> public static CaptchaBuilder AddSlideCaptcha(this IServiceCollection services, IConfiguration configuration, Action<CaptchaOptions> optionsAction = default) { services.Configure<CaptchaOptions>(configuration?.GetSection("SlideCaptcha")); //对所需验证的参数进行检查，如果参数不合法就抛一个异常出来 if (optionsAction != null) services.PostConfigure(optionsAction); var builder = new CaptchaBuilder(services); services.AddSingleton<IResourceProvider, OptionsResourceProvider>(); services.AddSingleton<IResourceProvider, EmbeddedResourceProvider>(); services.AddSingleton<IResourceHandlerManager, CachedResourceHandlerManager>(); services.AddSingleton<IResourceManager, DefaultResourceManager>(); services.AddSingleton<ISliderCaptchaImageGenerator, SliderCaptchaImageGenerator>(); services.AddSingleton<IResourceHandler, FileResourceHandler>(); services.AddSingleton<IResourceHandler, EmbeddedResourceHandler>(); services.AddScoped<ICaptcha, ImageCaptcha>(); services.AddScoped<IStorage, DefaultStorage>(); services.AddScoped<IValidator, SimpleValidator>(); return builder; } } } ServiceCollectionExtensions.cs
ServiceCollectionExtensions.cs用于实现IServiceCollection的Replace方法
using System; using System.Collections.Generic; using System.Linq; namespace Microsoft.Extensions.DependencyInjection { public static class ServiceCollectionExtensions { public static IServiceCollection Replace<TService, TImplementation>(this IServiceCollection services) where TImplementation : TService { return services.Replace<TService>(typeof(TImplementation)); } public static IServiceCollection Replace<TService>(this IServiceCollection services, Type implementationType) { return services.Replace(typeof(TService), implementationType); } public static IServiceCollection Replace(this IServiceCollection services, Type serviceType, Type implementationType) { if (services == null) { throw new ArgumentNullException(nameof(services)); } if (serviceType == null) { throw new ArgumentNullException(nameof(serviceType)); } if (implementationType == null) { throw new ArgumentNullException(nameof(implementationType)); } if (!services.TryGetDescriptors(serviceType, out var descriptors)) { throw new ArgumentException($"No services found for {serviceType.FullName}.", nameof(serviceType)); } foreach (var descriptor in descriptors) { var index = services.IndexOf(descriptor); services.Insert(index, descriptor.WithImplementationType(implementationType)); services.Remove(descriptor); } return services; } private static bool TryGetDescriptors(this IServiceCollection services, Type serviceType, out ICollection<ServiceDescriptor> descriptors) { return (descriptors = services.Where(service => service.ServiceType == serviceType).ToArray()).Any(); } private static ServiceDescriptor WithImplementationType(this ServiceDescriptor descriptor, Type implementationType) { return new ServiceDescriptor(descriptor.ServiceType, implementationType, descriptor.Lifetime); } } } SlideCaptchaException.cs
SlideCaptchaException.cs 实现自定义异常信息。
using System; namespace SlideCaptcha.Exceptions { public class SlideCaptchaException : Exception { public SlideCaptchaException() : base() { } public SlideCaptchaException(string message) : base(message) { } public SlideCaptchaException(string message, Exception innerException) : base(message, innerException) { } } } 下载方式：
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