使用Blazor HttpClient Core3.1.0预览3添加Jwt Asp.net Handler

Question

最近，我将我的项目从Asp.Net Core 3.0升级到了最新的构建Asp.Net Core 3.1.0 preview 3。

我的项目正在客户机中运行Blazor，我还拦截管道，将一个Jwt添加到使用扩展JwtTokenHeaderHandler的DelegatingHandler发送回服务器的每个请求的头上。

我在我的startup.cs blazor.client项目中添加了以下内容：

        services.AddSingleton<HttpClient>(s =>
        {
            // Creating the URI helper needs to wait until the JS Runtime is initialized, so defer it.
            var uriHelper = s.GetRequiredService<NavigationManager>();
            var myHandler = s.GetRequiredService<JwtTokenHeaderHandler>();
            myHandler.InnerHandler = new WebAssemblyHttpMessageHandler();
            return new HttpClient(myHandler)
            {
                BaseAddress = new Uri(uriHelper.BaseUri)
            };
        }); 

但是，自从升级之后，WebAssemblyHttpMessageHandler()似乎不再可用了？

我找不到任何关于如何修复这种方法的文档。

有人能告诉我如何纠正这个问题吗？

基于Aqua答案的更新

将以下代码添加到我的Startup.cs之后；

        services.AddTransient(p =>
         {
             var wasmHttpMessageHandlerType = Assembly.Load("WebAssembly.Net.Http")
                 .GetType("WebAssembly.Net.Http.HttpClient.WasmHttpMessageHandler");
             var constructor = wasmHttpMessageHandlerType.GetConstructor(Array.Empty<Type>());
             return constructor.Invoke(Array.Empty<object>()) as HttpMessageHandler;
         })
         .AddTransient<JwtTokenHeaderHandler>();

从我的Authorized文件中调用一个.razor获取端点；

var response = await Http.GetAsync<ContactTypeOutputModel[]>("ContactTypes/all");

(上面只是使用扩展方法的类型包装服务响应)；

    public static async Task<ServiceResponse<T>> GetAsync<T>(
        this HttpClient httpClient, string url)
    {
        var response = await httpClient.GetAsync(url);

        return await BuildResponse<T>(response);
    }

我还能拿到401的服务吗？而没有输出日志来表示服务正在被使用？

public class JwtTokenHeaderHandler : DelegatingHandler
{
    private readonly IAppLocalStorageService _localStorage;     
    private readonly ILogger<JwtTokenHeaderHandler> _logger;

    private readonly HttpMessageHandler _innerHandler;
    private readonly MethodInfo _method;

    public JwtTokenHeaderHandler(IAppLocalStorageService localStorage, HttpMessageHandler innerHandler, ILogger<JwtTokenHeaderHandler> logger)
    {
        _localStorage = localStorage;   
        _logger = logger;

        _innerHandler = innerHandler;
        var type = innerHandler.GetType();
        _method = type.GetMethod("SendAsync", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.InvokeMethod) ?? throw new InvalidOperationException("Cannot get SendAsync method");
        WebAssemblyHttpMessageHandlerOptions.DefaultCredentials = FetchCredentialsOption.Include;
    }

    protected override async Task<HttpResponseMessage> SendAsync(
        HttpRequestMessage request,
        CancellationToken cancellationToken)
    {
        _logger.LogDebug("Adding Jwt to Header from JwtTokenHeaderHandler: SendAsync");
        _logger.LogDebug($"Does header contain 'bearer' token: {!request.Headers.Contains("bearer")}");

        if (!request.Headers.Contains("bearer"))
        {

            _logger.LogDebug("Adding Bearer Token to Header");

            var savedToken = await _localStorage.GetTokenAsync();

            _logger.LogDebug($"Saved Token is : {savedToken}");

            if (!string.IsNullOrWhiteSpace(savedToken))
            {
                request.Headers.Authorization = new AuthenticationHeaderValue("bearer", savedToken);
            }
        }

        //return await base.SendAsync(request, cancellationToken);
        return await (_method.Invoke(_innerHandler, new object[] { request, cancellationToken }) as Task<HttpResponseMessage>);
    }
}

知道为什么这个没被击中吗？

Answer 1

由于无法向WebAssembly.Net.Http.添加依赖项，WebAssemblyHttpMessageHandler已被Mono的WasmHttpMessageHandler替换为了为blazor创建一个DependencyHandler，我做了一个小黑客：

    public class OidcDelegationHandler : DelegatingHandler
    {
        private readonly IUserStore _userStore;
        private readonly HttpMessageHandler _innerHanler;
        private readonly MethodInfo _method;

        public OidcDelegationHandler(IUserStore userStore, HttpMessageHandler innerHanler)
        {
            _userStore = userStore ?? throw new ArgumentNullException(nameof(userStore));
            _innerHanler = innerHanler ?? throw new ArgumentNullException(nameof(innerHanler));
            var type = innerHanler.GetType();
            _method = type.GetMethod("SendAsync", BindingFlags.NonPublic | BindingFlags.Instance | BindingFlags.InvokeMethod) ?? throw new InvalidOperationException("Cannot get SendAsync method");
            WebAssemblyHttpMessageHandlerOptions.DefaultCredentials = FetchCredentialsOption.Include;
        }
        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
        {
            request.Headers.Authorization = new AuthenticationHeaderValue(_userStore.AuthenticationScheme, _userStore.AccessToken);            
            return _method.Invoke(_innerHanler, new object[] { request, cancellationToken }) as Task<HttpResponseMessage>;
        }
    }

在DI中将其设置为：

return services
    .AddTransient(p =>
    {
        var wasmHttpMessageHandlerType =  Assembly.Load("WebAssembly.Net.Http")
            .GetType("WebAssembly.Net.Http.HttpClient.WasmHttpMessageHandler");
        var constructor = wasmHttpMessageHandlerType.GetConstructor(Array.Empty<Type>());
        return constructor.Invoke(Array.Empty<object>()) as HttpMessageHandler;
    })

完整的代码是这里