c# - 如何在 Xamarin.Forms 上调用 HTTP2

Question

gRpc for Xamarin.Forms with .Net Standart 2.0 适用于 http2，因此它应该是进行 HttpClient 调用或重用现有 gRpc 功能的某种方式。可能是我错过了一些东西。

重现问题的示例应用程序。您需要在某处托管 gRpc 服务。 WebClient 调用位于 AboutPage.xaml.cs aslo 测试项目中，其中包含 web 文件夹中的 asp core 3.1。
XamarinHttp2WithBackend GitHub

休耕说明 Microsoft.com - HttpClient Stack and SSL/TLS Implementation Selector for Android和 Stackoverflow.com - Use HTTP 2 with HttpClient in .Net也没有帮助。

对于 Asp Core 3.1 控制台应用程序，您可以执行(如下)并且可以工作。它不适用于 2.2 及更低版本

AppContext.SetSwitch("System.Net.Http.SocketsHttpHandler.Http2UnencryptedSupport", true);

var client = new HttpClient();
var req = new HttpRequestMessage(HttpMethod.Get, $"http://123.123.123.123:1234/ping/")
{
    Version = new Version(2, 0),
};

var response = await client.SendAsync(req);

在 Xamarin 上使用相同会引发异常

 Java.IO.IOException: unexpected end of stream on com.android.okhttp.Address@ce6f1800 ---> Java.IO.EOFException: 
 not found: size=17 content=0000080700000000000000000000000001...
01-23 15:10:13.472 I/MonoDroid(28829):    --- End of inner exception stack trace ---
01-23 15:10:13.472 I/MonoDroid(28829):   at Java.Interop.JniEnvironment+InstanceMethods.CallIntMethod (Java.Interop.JniObjectReference instance, Java.Interop.JniMethodInfo method, Java.Interop.JniArgumentValue* args) [0x0006e] in <e7e2d009b69d4e5f9a00e6ee600b8a8e>:0 
01-23 15:10:13.472 I/MonoDroid(28829):   at Java.Interop.JniPeerMembers+JniInstanceMethods.InvokeVirtualInt32Method (System.String encodedMember, Java.Interop.IJavaPeerable self, Java.Interop.JniArgumentValue* parameters) [0x0002a] in <e7e2d009b69d4e5f9a00e6ee600b8a8e>:0 
01-23 15:10:13.472 I/MonoDroid(28829):   at Java.Net.HttpURLConnection.get_ResponseCode () [0x0000a] in <d706cf8faf5542949900cf6d57864528>:0 
01-23 15:10:13.472 I/MonoDroid(28829):   at Xamarin.Android.Net.AndroidClientHandler+<>c__DisplayClass46_0.<DoProcessRequest>b__2 () [0x00000] in <d706cf8faf5542949900cf6d57864528>:0 
01-23 15:10:13.472 I/MonoDroid(28829):   at System.Threading.Tasks.Task`1[TResult].InnerInvoke () [0x0000f] in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/release/external/corert/src/System.Private.CoreLib/src/System/Threading/Tasks/Future.cs:534 
01-23 15:10:13.472 I/MonoDroid(28829):   at System.Threading.Tasks.Task.Execute () [0x00000] in /Users/builder/jenkins/workspace/archive-mono/2019-08/android/release/external/corert/src/System.Private.CoreLib/src/System/Threading/Tasks/Task.cs:2319 

DEBUG 的解决方案设置

<PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Debug|AnyCPU' ">
<DebugSymbols>true</DebugSymbols>
<DebugType>portable</DebugType>
<Optimize>false</Optimize>
<OutputPath>bin\Debug</OutputPath>
<DefineConstants>DEBUG;</DefineConstants>
<ErrorReport>prompt</ErrorReport>
<WarningLevel>4</WarningLevel>
<AndroidLinkMode>None</AndroidLinkMode>
<AotAssemblies>false</AotAssemblies>
<EnableLLVM>false</EnableLLVM>
<AndroidEnableProfiledAot>false</AndroidEnableProfiledAot>
<BundleAssemblies>false</BundleAssemblies>
<AndroidSupportedAbis>
</AndroidSupportedAbis>
<EmbedAssembliesIntoApk>false</EmbedAssembliesIntoApk>
<Debugger>Xamarin</Debugger>
<AndroidUseSharedRuntime>true</AndroidUseSharedRuntime>
<AndroidUseAapt2>false</AndroidUseAapt2>
<AndroidHttpClientHandlerType>Xamarin.Android.Net.AndroidClientHandler</AndroidHttpClientHandlerType>
<AndroidTlsProvider>btls</AndroidTlsProvider>
</PropertyGroup>

我的asp启动。我将它与grp服务一起使用。
发布为控制台单个可执行文件

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddGrpc((options => { options.EnableDetailedErrors = true; }));
        services.AddMvc(options => options.EnableEndpointRouting = false);

        //services.AddDbContext<PuvDbContext>();
        services.AddScoped<IAccountService, AccountService>();
        services.AddSingleton<IFirebirdService, FirebirdService>();
        services.AddSingleton<IClassificatorService, ClassificatorService>();
        services.AddSingleton<IClassificatorRepository, ClassificatorRepository>();

        services.AddControllers();
    }

    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseRouting();
        app.UseMvcWithDefaultRoute();

        app.UseStaticFiles();
        app.UseMvc();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapGrpcService<GreeterService>();
            endpoints.MapGrpcService<AccountController>();
            endpoints.MapGrpcService<ReviewController>();
            endpoints.MapGrpcService<StaticDataController>();
            endpoints.MapGrpcService<TaskController>();
            endpoints.MapControllers();
        });


    }
}

我调用的 Controller 方法

[Route("files")]
public class FileController : Controller
{
    public FileController()
    {       
    }

    [HttpGet("hi")]
    public async Task<HttpResponseMessage> GetTest()
    {
        return new HttpResponseMessage(HttpStatusCode.OK);
    }
}

Answer 1

有几个可能的解决方案:

如果您只是将 Target 框架更新到 .NET Standard 2.1 或更高版本，那么应该可以解决您的问题。如果您不能这样做，因为您的解决方案较旧，请尝试其余的。

打开您的 Android 项目选项，然后在“Android build”中，将 HttpClient 实现值更新为“AndroidClientHandler”或任何其他值并重试，这已添加到该配置的 CSPROJ 中

<AndroidHttpClientHandlerType>Xamarin.Android.Net.AndroidClientHandler</AndroidHttpClientHandlerType>
<AndroidTlsProvider>btls</AndroidTlsProvider>

然后我只需要在我的 HttpClient 中传递这个 HttpClientHandler:

httpClient = new HttpClient(new HttpClientHandler()
{
    UseProxy = true
});

如果这也不起作用，那么您必须使用这两个 nuget 包之一 http2dotnet ( https://github.com/Matthias247/http2dotnet ) 或 httptwo ( https://github.com/Redth/HttpTwo )，如他们的 GitHub 所示:

// Uri to request
var uri = new Uri ("http://somesite.com:80/index.html");

// Create a Http2Client
var http2 = new Http2Client (uri);

// Specify any custom headers
var headers = new NameValueCollection ();
headers.Add ("some-header", "value");

// For some requests you may have a request body
byte[] data = null; 

// Await our response
var response = await http2.Send (uri, HttpMethod.Get, headers, data);