.Net Core 扩展使用Refit
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在.net core 2.1当中，目前可以是用HttpClientFactory进行Http的调用，它的使用方法我不再多说，具体参见（https://docs.microsoft.com/zh-cn/aspnet/core/fundamentals/http-requests?view=aspnetcore-2.2#consumption-patterns）。微软的官网写的非常详细了。
在调用过程中使用Refit可以进行强类型的客户端调用，个人比较喜欢这个。目前还有一个组件是老九大佬写的一个类似的客户端（https://github.com/dotnetcore/WebApiClient）
在WebApi当中使用Refit。
???????public void ConfigureServices(IServiceCollection services) ???????{ ???????????services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1); ???????????services.AddHttpClient("github", c => ???????????{ ???????????????c.BaseAddress = new Uri("https://api.github.com"); ???????????}) ???.AddTypedClient(c => Refit.RestService.For<IGitHubApi>(c)); ???????????services.AddRefitClient<IGitHubApi>(); ???????} ???????????????接口的定义为：
???[Headers("User-Agent: Refit Integration Tests")] ???//[RefitClient("github")] ???public interface IGitHubApi ???{ ???????[Get("/users/{username}")] ???????Task<User> GetUser(string userName); ???}当我们有很多接口需要注入的时候，就得写很多的类似强类型的AddRefitClient的代码，个人觉得非常的麻烦。是否能够根据标签程序集进行批量注入。
Refit的注入，其实注入的是一个RestService
???????public static IHttpClientBuilder AddRefitClient<T>(this IServiceCollection services, RefitSettings settings = null) where T : class ???????{ ???????????services.AddSingleton(provider => RequestBuilder.ForType<T>(settings)); ???????????return services.AddHttpClient(UniqueName.ForType<T>()) ??????????????????????????.AddTypedClient((client, serviceProvider) => RestService.For<T>(client, serviceProvider.GetService<IRequestBuilder<T>>())); ???????}具体的类型是在代码编译阶段用BuildTask生成了带有RefitHttpAttribute的接口类型的实体类。
具体创建的类型如下：
[ExcludeFromCodeCoverage, DebuggerNonUserCode, Preserve]internal class AutoGeneratedIGitHubApi : IGitHubApi{ ???// Fields ???[CompilerGenerated, DebuggerBrowsable(0)] ???private HttpClient <Client>k__BackingField; ???private readonly IRequestBuilder requestBuilder; ???// Methods ???public AutoGeneratedIGitHubApi(HttpClient client, IRequestBuilder requestBuilder) ???{ ???????this.Client = client; ???????this.requestBuilder = requestBuilder; ???} ???public virtual Task<User> GetUser(string userName) ???{ ???????object[] objArray1 = new object[] { userName }; ???????object[] objArray = objArray1; ???????Type[] typeArray1 = new Type[] { typeof(string) }; ???????return (Task<User>) this.requestBuilder.BuildRestResultFuncForMethod("GetUser", typeArray1, null)(this.Client, objArray); ???} ???// Properties ???public HttpClient Client { get; protected set; }}目前我们要解决的是如何批量的进行注入的问题：个人在Refit的源码上添加了一些代码以支持批量注入
??//配置的实体 ???public class ApiSettings ???{ ???????public List<ApiOption> Apis { get; set; } = new List<ApiOption>(); ???} ???public class ApiOption ???{ ???????????public string Name { get; set; } ???????public string Version { get; set; } ???????//httpClient的baseAddress的配置 ???????public string Url { get; set; } ???} ???//配置的搜索的程序集的名称 ???public class DISettings ???{ ???????public List<string> RefitClientAssemblyNames { get; set; } = new List<string>(); ???} ???/// <summary> ???/// 批量注入时打上这个标签标明是Refit的接口 ???/// </summary> ???public class RefitClientAttribute : Attribute ???{ ???????/// <summary> ???????/// appsetting中的apiname ???????/// </summary> ???????public string ApiName { get; set; } ???????public RefitClientAttribute(string apiName) ???????{ ???????????ApiName = apiName; ???????} ???} ???/// <summary> ???/// 基于HttpClient的扩展方法 ???/// </summary> ???public static class RefitHttpClientExtension ???{ ???????public static IServiceCollection ScanAddHttpClient(this IServiceCollection serviceCollection, ApiSettings settings) ???????{ ???????????#region 批量注入HttpClient ??????????????????????if (settings == null) ???????????{ ???????????????throw new ArgumentNullException("settings"); ???????????} ???????????var apis = settings.Apis; ???????????if (apis == null || apis.Count == 0) ???????????{ ???????????????throw new ArgumentNullException("settings.Apis"); ???????????} ???????????foreach (var ass in apis) ???????????{ ???????????????serviceCollection.AddHttpClient(ass.Name).ConfigureHttpClient(client => client.BaseAddress = new Uri(ass.Url)); ???????????} ???????????#endregion ???????????return serviceCollection; ???????} ???????public static IServiceCollection ScanAddRefitClient(this IServiceCollection serviceCollection, IConfiguration configration, RefitSettings refitSettings = null) ???????{ ???????????DISettings dISettings = configration.GetSection("DISettings").Get<DISettings>(); ???????????if (dISettings == null) ???????????{ ???????????????throw new ArgumentNullException("dISettings", "配置文件中不存在DISettings节点"); ???????????} ???????????if (dISettings == null || dISettings.RefitClientAssemblyNames == null || dISettings.RefitClientAssemblyNames.Count == 0) ???????????{ ???????????????throw new ArgumentNullException("dISettings.RefitClientAssemblyNames", "配置文件DISettings节点不存在RefitClientAssemblyNames节点！！"); ???????????} ???????????ApiSettings apiSettings = configration.GetSection("ApiSettings").Get<ApiSettings>(); ???????????if (apiSettings == null) ???????????{ ???????????????throw new ArgumentNullException("apiSettings", "配置文件中不存在ApiSettings节点"); ???????????} ???????????if (apiSettings.Apis == null || apiSettings.Apis.Count == 0) ???????????{ ???????????????throw new ArgumentNullException("apiSettings.Apis", "配置文件ApiSettings节点不存在Apis节点！！"); ???????????} ???????????return serviceCollection.ScanAddRefitClient(apiSettings, dISettings, refitSettings); ???????} ???????public static IServiceCollection ScanAddRefitClient(this IServiceCollection serviceCollection, ApiSettings apiSettings, DISettings dISettings, RefitSettings refitSettings = null) ???????{ ???????????#region 批量注入HttpClient ???????????serviceCollection.ScanAddHttpClient(apiSettings); ???????????#endregion ???????????var registTypes = GetAttributeType(dISettings); ???????????serviceCollection.ScanAddRefitClient(registTypes, refitSettings); ???????????return serviceCollection; ???????} ???????public static IServiceCollection ScanAddRefitClient(this IServiceCollection serviceCollection, List<Type> registTypes, RefitSettings refitSettings = null) ???????{ ???????????foreach (var type in registTypes) ???????????{ ???????????????var name = type.GetCustomAttribute<RefitClientAttribute>().ApiName; ???????????????serviceCollection.AddRefitClient(type, name, refitSettings); ???????????} ???????????return serviceCollection; ???????} ???????private static List<Type> GetAttributeType(DISettings options) ???????{ ???????????var registTypes = new List<Type>(); ???????????var assemblys = options.RefitClientAssemblyNames; ???????????foreach (var assembly in assemblys) ???????????{ ???????????????registTypes.AddRange(GetAssemblyType(assembly, type => ???????????????{ ???????????????????var refitAttrs = type.GetCustomAttributes<RefitClientAttribute>(); ???????????????????if (refitAttrs == null || refitAttrs.Count() == 0) ???????????????????{ ???????????????????????return false; ???????????????????} ???????????????????else ???????????????????{ ???????????????????????return true; ???????????????????} ???????????????})); ???????????} ???????????return registTypes; ???????} ???????private static List<Type> GetAssemblyType(string assemblyName, Predicate<Type> predicate = null) ???????{ ???????????var registTypes = new List<Type>(); ???????????var ass = Assembly.Load(new AssemblyName(assemblyName)); ???????????var types = ass.DefinedTypes.Where(p => p.IsPublic && p.IsInterface).Select(x => x.AsType())?.ToList(); ???????????foreach (var type in types) ???????????{ ???????????????if (predicate == null) ???????????????{ ???????????????????registTypes.Add(type); ???????????????????continue; ???????????????} ???????????????if (predicate(type)) ???????????????{ ???????????????????registTypes.Add(type); ???????????????} ???????????} ???????????return registTypes; ???????} ???} ???在HttpClientFactoryExtensions扩展类中新增了两个基于Type的扩展方法而不是泛型的扩展方法
/// <summary> ???????/// Adds a Refit client to the DI container ???????/// </summary> ???????/// <param name="services">container</param> ???????/// <param name="t">type of refit interface</param> ???????/// <param name="httpclientName">httpclient‘s name</param> ???????/// <param name="settings">Optional. Settings to configure the instance with</param> ???????/// <returns></returns> ???????public static IServiceCollection AddRefitClient(this IServiceCollection services,Type t,string httpclientName, RefitSettings settings = null) ???????{ ???????????var builder = RequestBuilder.ForType(t, settings); ???????????services.AddSingleton(provider => builder); ???????????services.AddSingleton(t, provider => ???????????{ ???????????????var client=provider.GetService<IHttpClientFactory>().CreateClient(httpclientName); ???????????????if (client == null) ???????????????{ ???????????????????throw new Exception($"please inject the httpclient ?named {httpclientName} httpclient!! "); ???????????????} ???????????????return RestService.For(client, builder, t); ???????????}); ???????????return services; ???????} ???????/// <summary> ???????/// Adds a Refit client to the DI container ???????/// </summary> ???????/// <param name="services">container</param> ???????/// <param name="t">type of refit interface</param> ???????/// <param name="client>httpclient</param> ???????/// <param name="settings">Optional. Settings to configure the instance with</param> ???????/// <returns></returns> ???????public static IServiceCollection AddRefitClient(this IServiceCollection services, Type t, HttpClient client,RefitSettings settings = null) ???????{ ???????????var builder = RequestBuilder.ForType(t, settings); ???????????services.AddSingleton(provider => builder); ???????????services.AddSingleton(t, provider => ???????????{ ???????????????return RestService.For(client, builder, t); ???????????}); ???????????return services; ???????}第三：在是基于Refit的源码RestService改写下能够支持RestService.For（Type interType)的方法
???????public static object For(HttpClient client, IRequestBuilder builder,Type t) ???????{ ???????????var generatedType = typeMapping.GetOrAdd(t, GetGeneratedType(t)); ???????????return Activator.CreateInstance(generatedType, client, builder); ???????} ???????//它就是在这里获取生成好的接口的注入类型的名字 ???????static Type GetGeneratedType(Type t) ???????{ ???????????string typeName = UniqueName.ForType(t); ???????????var generatedType = Type.GetType(typeName); ???????????if (generatedType == null) ???????????{ ???????????????var message = t.Name + " doesn‘t look like a Refit interface. Make sure it has at least one " + "method with a Refit HTTP method attribute and Refit is installed in the project."; ???????????????throw new InvalidOperationException(message); ???????????} ???????????return generatedType; ???????} ???????????????//获取名字方法也是泛型的也要加一个基于Type的 ???????public static string ForType(Type t) ???????{ ???????????string typeName; ???????????if (t.IsNested) ???????????{ ???????????????var className = "AutoGenerated" + t.DeclaringType.Name + t.Name; ???????????????typeName = t.AssemblyQualifiedName.Replace(t.DeclaringType.FullName + "+" + t.Name, t.Namespace + "." + className); ???????????} ???????????else ???????????{ ???????????????var className = "AutoGenerated" + t.Name; ???????????????if (t.Namespace == null) ???????????????{ ???????????????????className = $"{className}.{className}"; ???????????????} ???????????????typeName = t.AssemblyQualifiedName.Replace(t.Name, className); ???????????} ???????????return typeName; ???????}在AppSetting文件当中配置一些配置：
{ ?"ApiSettings": { ???"Apis": [ ?????{ ???????"Name": "gitHubApi", ???????"Version": "", ???????"Url": "https://api.github.com" ?????} ???] ?}, ?"DISettings": { ???"RefitClientAssemblyNames": [ "RefitWebTest" ] ?}}Refit的接口主要打上标签即可
???[Headers("User-Agent: Refit Integration Tests")] ???//参数的名字和配置文件的Apis:Name一致即可 ???[RefitClient("gitHubApi")] ???public interface IGitHubApi ???{ ???????[Get("/users/{username}")] ???????Task<User> GetUser(string userName); ???}改写以后的使用：
???????????//批量注入带有RefitClientAttribute标签的接口 ???????????services.ScanAddRefitClient(Configuration); ???????????这样就实现了基于Refit的批量注入，注入的HttpClient的名字为配置文件当中的名字。
最后打包成Nuget包才能正确的使用，个人尝试发现必须Nuget包的名字是Refit才能正确的生成接口的代理类，（我知道改包名不是很好=。=）改个nuget的名字都不行，不知道为什么不知道有没有大佬知道，望指教！！
贴一下Refit的BuildTask的targets文件
<?xml version="1.0" encoding="utf-8"?><Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003"> ?<PropertyGroup> ???<CoreCompileDependsOn> ?????$(CoreCompileDependsOn); ?????GenerateRefitStubs; ???</CoreCompileDependsOn> ?</PropertyGroup> ???<PropertyGroup> ???<IntermediateOutputPath Condition="$(IntermediateOutputPath) == ‘‘ Or $(IntermediateOutputPath) == ‘*Undefined*‘">$(MSBuildProjectDirectory)obj\$(Configuration)\</IntermediateOutputPath> ???<RefitTaskAssemblyFile Condition="‘$(MSBuildRuntimeType)‘ == ‘Core‘">$(MSBuildThisFileDirectory)..\MSBuildCore20\InterfaceStubGenerator.BuildTasks.dll</RefitTaskAssemblyFile> ???<RefitTaskAssemblyFile Condition="‘$(MSBuildRuntimeType)‘ != ‘Core‘">$(MSBuildThisFileDirectory)..\MSBuildFull46\InterfaceStubGenerator.BuildTasks.dll</RefitTaskAssemblyFile> ???<RefitMinCoreVersionRequired>2.0</RefitMinCoreVersionRequired> ???<!-- Our default CLI version for error checking purposes --> ???<RefitNetCoreAppVersion>$(BundledNETCoreAppTargetFrameworkVersion)</RefitNetCoreAppVersion> ???<RefitNetCoreAppVersion Condition="‘$(RefitNetCoreAppVersion)‘ == ‘‘">1.0</RefitNetCoreAppVersion> ???????<!-- ???Refit internal namespace to be added to internally generated Refit code. ????Can be overriden by user in case of namespace clashes. ???--> ???<RefitInternalNamespace Condition=" ‘$(RefitInternalNamespace)‘ == ‘‘ ">$(RootNamespace)</RefitInternalNamespace> ?</PropertyGroup> ???<UsingTask TaskName="Refit.Generator.Tasks.GenerateStubsTask" AssemblyFile="$(RefitTaskAssemblyFile)" /> ???<Target Name="GenerateRefitStubs" BeforeTargets="CoreCompile"> ???<Error Condition="‘$(MSBuildRuntimeType)‘ == ‘Core‘ and ‘$(RefitMinCoreVersionRequired)‘ > ‘$(RefitNetCoreAppVersion)‘ " ??????????Text="Refit requires at least the .NET Core SDK v2.0 to run with ‘dotnet build‘" ??????????ContinueOnError="false" ??????????/> ???????<GenerateStubsTask SourceFiles="@(Compile)" ??????????????????????BaseDirectory="$(MSBuildProjectDirectory)" ??????????????????????OutputFile="$(IntermediateOutputPath)\RefitStubs.g.cs" ??????????????????????RefitInternalNamespace="$(RefitInternalNamespace)" ??????????????????????/> ???<Message Text="Processed Refit Stubs" /> ??????<ItemGroup Condition="Exists(‘$(IntermediateOutputPath)\RefitStubs.g.cs‘)"> ???????<Compile Include="$(IntermediateOutputPath)\RefitStubs.g.cs" /> ???</ItemGroup> ?????</Target></Project>测试发现，只要改了打包的报名称，这个Task就不执行了，不知道为啥！！
如有知道忘告知！！
.Net Core 扩展使用Refit
原文地址：https://www.cnblogs.com/dasajia2lang/p/10268448.html