如何在 Xamarin.Forms 上调用 HTTP2

Question

带有 .Net Standart 2.0 的 Xamarin.Forms 的 gRpc 在 http2 上工作，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 调用在 AboutPage.xaml.cs aslo 测试项目中，在 web 文件夹中使用 asp core 3.1。 XamarinHttp2WithBackend GitHub

Fallowing 说明Microsoft.com - HttpClient Stack and SSL/TLS Implementation Selector for Android and Stackoverflow.com - 在 .Net 中使用 HTTP 2 和 HttpClient 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 上使用相同的抛出异常

 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();
        });


    }
}

我调用的控制器方法

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

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

Answer 1

有几种可能的解决方案：

1. 如果您只需将 Target 框架更新到 .NET Standard 2.1 或更高版本，那么这应该可以解决您的问题。如果由于您的解决方案较旧而无法做到这一点，请尝试其余的。
2. 打开 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，然后重试，这已添加到该配置的 CSPROJ 中

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

然后我只需在我的 HttpClient 中传递这个 HttpClientHandler 即可：

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

3. 如果这也不起作用，那么您必须使用这两个 nuget 包 http2dotnet ( https://github.com/Matthias247/http2dotnet ) 或 httptwo ( https://github.com/Redth/HttpTwo ) 之一作为替代在他们的 GitHub 中显示：

// 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);