Blazor WebAssembly 中的依赖注入、认证授权、WebSocket、JS互操作等(原标题 Blazor(WebAssembly) + .NETCore 实现斗地主)

　　Blazor Wasm 最近更新到了3.2.0-preview1，支持了WebSocket同时启动类也有所修改，我就把这个文章重新修改一下。

　　Blazor Wasm先在已经更新到3.2.0正式版，本文代码也已更新　　

　　之前群里大神发了一个 html5+ .NETCore的斗地主，刚好在看Blazor WebAssembly 就尝试重写试试。

　　这里主要介绍Blazor的依赖注入，认证与授权，WebSocket的使用，JS互操作等，完整实现可以查看github:https://github.com/saber-wang/FightLandlord/tree/master/src/BetGame.DDZ.WasmClient，在线演示：http://39.106.159.180:31000/

　　另外强调一下Blazor WebAssembly 是纯前端框架，所有相关组件等都会下载到浏览器运行，要和MVC、Razor Pages等区分开来

　　当前是基于NetCore3.1和Blazor WebAssembly 3.2.0 ，安装Vs 2019 16.6更新后就会附带Blazor WebAssembly模板。

　　

　　

　　选择Blazor应用，跟着往下就会看到Blazor WebAssembly App模板，如果看不到就在ASP.NET Core3.0和3.1之间切换一下。

　　

　　新建后项目结构如下。

　　

　　一眼看过去，大体和Razor Pages 差不多。Program.cs中创建了一个WebAssemblyHostBuilder，然后指定启动容器，代码非常简单。

　　

public static async Task Main(string[] args)
        {
            var builder = WebAssemblyHostBuilder.CreateDefault(args);

            builder.RootComponents.Add<App>("app");

            await builder.Build().RunAsync();
        }

　　

　　Blazor WebAssembly 中也支持DI，注入方式与生命周期与ASP.NET Core一致，但是Scope生命周期不太一样，注册的服务的行为类似于 Singleton 服务。

　　在WebAssemblyHostBuilder中有一个Services属性用来注册服务

public static async Task Main(string[] args)
        {
            var builder = WebAssemblyHostBuilder.CreateDefault(args);

            builder.Services.AddScoped<ApiService>();
            builder.Services.AddScoped<FunctionHelper>();
            builder.Services.AddScoped<LocalStorage>();
            builder.Services.AddScoped<CustomAuthStateProvider>();
            builder.Services.AddScoped<AuthenticationStateProvider>(s => s.GetRequiredService<CustomAuthStateProvider>());
            builder.Services.AddAuthorizationCore(c=> {
                c.AddPolicy("default", a => a.RequireAuthenticatedUser());
                c.DefaultPolicy = c.GetPolicy("default");
            });
            builder.Services.AddScoped(sp=>new ClientWebSocket());

            builder.RootComponents.Add<App>("app");
　　　　　　　builder.Services.AddTransient(sp => new HttpClient { BaseAddress = new Uri(builder.HostEnvironment.BaseAddress) });
            WebAssemblyHttpMessageHandlerOptions.DefaultCredentials = FetchCredentialsOption.Include;
            await builder.Build().RunAsync();
        }

　　

　　默认已注入了IJSRuntime，NavigationManager，具体可以看官方文档介绍。

　　App.razor中定义了路由和默认路由，修改添加AuthorizeRouteView和CascadingAuthenticationState以支持AuthorizeView、AuthenticationState等用于认证和获取当前的身份验证状态。

　　

<Router AppAssembly="@typeof(Program).Assembly">
    <Found Context="routeData">
        <AuthorizeRouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />
    </Found>
    <NotFound>
        <CascadingAuthenticationState>
            <LayoutView Layout="@typeof(MainLayout)">
                <p>Sorry, there's nothing at this address.</p>
            </LayoutView>
        </CascadingAuthenticationState>
    </NotFound>
</Router>

　　自定义AuthenticationStateProvider并注入为AuthorizeView和CascadingAuthenticationState组件提供认证。

         builder.Services.AddScoped<CustomAuthStateProvider>();
            builder.Services.AddScoped<AuthenticationStateProvider>(s => s.GetRequiredService<CustomAuthStateProvider>());
            //在wasm中没有默认配置，所以需要设置一下
            builder.Services.AddAuthorizationCore(c=> {
                c.AddPolicy("default", a => a.RequireAuthenticatedUser());
                c.DefaultPolicy = c.GetPolicy("default");
            });

　　

CustomAuthStateProvider的实现如下。

public class CustomAuthStateProvider : AuthenticationStateProvider
    {
        ApiService _apiService;
        Player _playerCache;
        public CustomAuthStateProvider(ApiService apiService)
        {
            _apiService = apiService;
        }

        public override async Task<AuthenticationState> GetAuthenticationStateAsync()
        {
            var player = _playerCache??= await _apiService.GetPlayer();

            if (player == null)
            {
                return new AuthenticationState(new ClaimsPrincipal());
            }
            else
            {
                //认证通过则提供ClaimsPrincipal
                var user = Utils.GetClaimsIdentity(player);
                return new AuthenticationState(user);
            }

        }
        /// <summary>
        /// 通知AuthorizeView等用户状态更改
        /// </summary>
        public void NotifyAuthenticationState()
        {
            NotifyAuthenticationStateChanged(GetAuthenticationStateAsync());
        }
        /// <summary>
        /// 提供Player并通知AuthorizeView等用户状态更改
        /// </summary>
        public void NotifyAuthenticationState(Player player)
        {
            _playerCache = player;
            NotifyAuthenticationState();
        }
    }

　　我们这个时候就可以在组件上添加AuthorizeView根据用户是否有权查看来选择性地显示 UI，该组件公开了一个 AuthenticationState 类型的 context 变量，可以使用该变量来访问有关已登录用户的信息。

　　

<AuthorizeView>
    <Authorized>
     //认证通过 @context.User
    </Authorized>
    <NotAuthorized>
     //认证不通过
    </NotAuthorized>
</AuthorizeView>

　　 使身份验证状态作为级联参数

[CascadingParameter]
private Task<AuthenticationState> authenticationStateTask { get; set; }

　　获取当前用户信息

    private async Task GetPlayer()
    {
        var user = await authenticationStateTask;
        if (user?.User?.Identity?.IsAuthenticated == true)
        {
            player = new Player
            {
                Balance = Convert.ToInt32(user.User.FindFirst(nameof(Player.Balance)).Value),
                GameState = user.User.FindFirst(nameof(Player.GameState)).Value,
                Id = user.User.FindFirst(nameof(Player.Id)).Value,
                IsOnline = Convert.ToBoolean(user.User.FindFirst(nameof(Player.IsOnline)).Value),
                Nick = user.User.FindFirst(nameof(Player.Nick)).Value,
                Score = Convert.ToInt32(user.User.FindFirst(nameof(Player.Score)).Value),
            };
            await ConnectWebsocket();
        }
    }

　　注册用户并通知AuthorizeView状态更新

    private async Task GetOrAddPlayer(MouseEventArgs e)
    {
        GetOrAddPlayering = true;
        player = await ApiService.GetOrAddPlayer(editNick);
        this.GetOrAddPlayering = false;

        if (player != null)
        {
            CustomAuthStateProvider.NotifyAuthenticationState(player);
            await ConnectWebsocket();
        }

    }

　　JavaScript 互操作，虽然很希望完全不操作JavaScript，但目前版本的Web WebAssembly不太现实，例如弹窗、本地存储等，Blazor中操作JavaScript主要靠IJSRuntime 抽象,在重构的时候遇到最多的错误就是类型转换和索引溢出错误:)。

　　从Blazor操作JavaScript比较简单，操作的JavaScript需要是公开的，这里实现从Blazor调用alert和localStorage如下

public class FunctionHelper
    {
        private readonly IJSRuntime _jsRuntime;

        public FunctionHelper(IJSRuntime jsRuntime)
        {
            _jsRuntime = jsRuntime;
        }

        public ValueTask Alert(object message)
        {
            //无返回值使用InvokeVoidAsync
            return _jsRuntime.InvokeVoidAsync("alert", message);
        }
    }

public class LocalStorage
    {
        private readonly IJSRuntime _jsRuntime;
        private readonly static JsonSerializerOptions SerializerOptions = new JsonSerializerOptions();

        public LocalStorage(IJSRuntime jsRuntime)
        {
            _jsRuntime = jsRuntime;
        }
        public ValueTask SetAsync(string key, object value)
        {

            if (string.IsNullOrEmpty(key))
            {
                throw new ArgumentException("Cannot be null or empty", nameof(key));
            }

            var json = JsonSerializer.Serialize(value, options: SerializerOptions);

            return _jsRuntime.InvokeVoidAsync("localStorage.setItem", key, json);
        }
        public async ValueTask<T> GetAsync<T>(string key)
        {

            if (string.IsNullOrEmpty(key))
            {
                throw new ArgumentException("Cannot be null or empty", nameof(key));
            }

            //有返回值使用InvokeAsync
            var json =await _jsRuntime.InvokeAsync<string>("localStorage.getItem", key);
            if (json == null)
            {
                return default;
            }

            return JsonSerializer.Deserialize<T>(json, options: SerializerOptions);
        }
        public ValueTask DeleteAsync(string key)
        {
            return _jsRuntime.InvokeVoidAsync(
                $"localStorage.removeItem",key);
        }
    }

　　从JavaScript调用C#方法则需要把C#方法使用[JSInvokable]特性标记且必须为公开的。调用C#静态方法看这里，这里主要介绍调用C#的实例方法。

　　因为Blazor Wasm暂时不支持ClientWebSocket，所以我们用JavaScript互操作来实现WebSocket的链接与C#方法的回调。

　　使用C#实现一个调用JavaScript的WebSocket，并使用DotNetObjectReference.Create包装一个实例传递给JavaScript方法的参数（dotnetHelper），这里直接传递了当前实例。

    [JSInvokable]
    public async Task ConnectWebsocket()
    {
        Console.WriteLine("ConnectWebsocket");
        var serviceurl = await ApiService.ConnectWebsocket();
        //TODO ConnectWebsocket
        if (!string.IsNullOrWhiteSpace(serviceurl))
            await _jsRuntime.InvokeAsync<string>("newWebSocket", serviceurl, DotNetObjectReference.Create(this));
    }

　　JavaScript代码里使用参数(dotnetHelper)接收的实例调用C#方法(dotnetHelper.invokeMethodAsync('方法名',方法参数...))。

　

var gsocket = null;
var gsocketTimeId = null;
function newWebSocket(url, dotnetHelper)
{
    console.log('newWebSocket');
    if (gsocket) gsocket.close();
    gsocket = null;
    gsocket = new WebSocket(url);
    gsocket.onopen = function (e) {
        console.log('websocket connect');
        //调用C#的onopen();
        dotnetHelper.invokeMethodAsync('onopen')
    };
    gsocket.onclose = function (e) {
        console.log('websocket disconnect');
        dotnetHelper.invokeMethodAsync('onclose')
        gsocket = null;
        clearTimeout(gsocketTimeId);
        gsocketTimeId = setTimeout(function () {
            console.log('websocket onclose ConnectWebsocket');
            //调用C#的ConnectWebsocket();
            dotnetHelper.invokeMethodAsync('ConnectWebsocket');
            //_self.ConnectWebsocket.call(_self);
        }, 5000);
    };
    gsocket.onmessage = function (e) {
        try {
            console.log('websocket onmessage');
            var msg = JSON.parse(e.data);
            //调用C#的onmessage();
            dotnetHelper.invokeMethodAsync('onmessage', msg);
            //_self.onmessage.call(_self, msg);
        } catch (e) {
            console.log(e);
            return;
        }
    };
    gsocket.onerror = function (e) {
        console.log('websocket error');
        gsocket = null;
        clearTimeout(gsocketTimeId);
        gsocketTimeId = setTimeout(function () {
            console.log('websocket onerror ConnectWebsocket');
            dotnetHelper.invokeMethodAsync('ConnectWebsocket');
            //_self.ConnectWebsocket.call(_self);
        }, 5000);
    };
}

 　　Blazor中已经实现了Websocket，现在我们可以很简单的操作Websocket。

    public async Task ConnectWebsocket()
    {
        Console.WriteLine("ConnectWebsocket");
        //获取Websocket链接
        var serviceurl = await ApiService.ConnectWebsocket();
        if (!string.IsNullOrWhiteSpace(serviceurl))
        {
            wsConnectState = 1010;
            //链接Websocket
            await clientWebSocket.ConnectAsync(new Uri(serviceurl),default);
            //后台接收消息
            ReceiveMessages();
            //链接Websocket时调用
            await onopen();

            //await _jsRuntime.InvokeAsync<string>("newWebSocket", serviceurl, DotNetObjectReference.Create(this));
        }
    }

　　ReceiveMessages的实现如下

    private async Task ReceiveMessages()
    {
        List<byte> vs = new List<byte>();
        while (true)
        {
            Memory<byte> memory = new Memory<byte>(new byte[1024]);
            var res = await clientWebSocket.ReceiveAsync(memory, default);
            var bt = memory.ToArray().Take(res.Count);
            vs.AddRange(bt);
            if (res.EndOfMessage)
            {
                if (res.MessageType == WebSocketMessageType.Close)
                {
                    onclose();
                }
                else
                {
                    var jsonDocument = JsonSerializer.Deserialize<object>(vs.ToArray());
                    vs.Clear();
                    await onmessage(jsonDocument);
                }
                //当前方法在后台执行，所以我们需要手动更新UI
                StateHasChanged();
            }
        }
    }

　　

　　onopen,onclose,onmessage实现如下

public async Task onopen()
    {

        Console.WriteLine("websocket connect");
        wsConnectState = 1;
        await GetDesks();
        StateHasChanged();
    }
    public void onclose()
    {
        Console.WriteLine("websocket disconnect");
        wsConnectState = 0;
    }

    public async Task onmessage(object msgobjer)
    {
        try
        {
            var jsonDocument = JsonSerializer.Deserialize<object>(msgobjer.ToString());
            if (jsonDocument is JsonElement msg)
            {
                if (msg.TryGetProperty("type", out var element) && element.ValueKind == JsonValueKind.String)
                {
                    Console.WriteLine(element.ToString());
                    if (element.GetString() == "Sitdown")
                    {
                        Console.WriteLine(msg.GetProperty("msg").GetString());
                        var deskId = msg.GetProperty("deskId").GetInt32();
                        foreach (var desk in desks)
                        {
                            if (desk.Id.Equals(deskId))
                            {
                                var pos = msg.GetProperty("pos").GetInt32();
                                Console.WriteLine(pos);
                                var player = JsonSerializer.Deserialize<Player>(msg.GetProperty("player").ToString());
                                switch (pos)
                                {
                                    case 1:
                                        desk.player1 = player;
                                        break;
                                    case 2:
                                        desk.player2 = player;
                                        break;
                                    case 3:
                                        desk.player3 = player;
                                        break;

                                }
                                break;
                            }
                        }
                    }
                    else if (element.GetString() == "Standup")
                    {
                        Console.WriteLine(msg.GetProperty("msg").GetString());
                        var deskId = msg.GetProperty("deskId").GetInt32();
                        foreach (var desk in desks)
                        {
                            if (desk.Id.Equals(deskId))
                            {
                                var pos = msg.GetProperty("pos").GetInt32();
                                Console.WriteLine(pos);
                                switch (pos)
                                {
                                    case 1:
                                        desk.player1 = null;
                                        break;
                                    case 2:
                                        desk.player2 = null;
                                        break;
                                    case 3:
                                        desk.player3 = null;
                                        break;

                                }
                                break;
                            }
                        }
                    }
                    else if (element.GetString() == "GameStarted")
                    {
                        Console.WriteLine(msg.GetProperty("msg").GetString());
                        currentChannel.msgs.Insert(0, msg);
                    }
                    else if (element.GetString() == "GameOvered")
                    {
                        Console.WriteLine(msg.GetProperty("msg").GetString());
                        currentChannel.msgs.Insert(0, msg);
                    }
                    else if (element.GetString() == "GamePlay")
                    {

                        ddzid = msg.GetProperty("ddzid").GetString();
                        ddzdata = JsonSerializer.Deserialize<GameInfo>(msg.GetProperty("data").ToString());
                        Console.WriteLine(msg.GetProperty("data").ToString());
                        stage = ddzdata.stage;
                        selectedPokers = new int?[55];
                        if (playTips.Any())
                            playTips.RemoveRange(0, playTips.Count);
                        playTipsIndex = 0;

                        if (this.stage == "游戏结束")
                        {
                            foreach (var ddz in this.ddzdata.players)
                            {
                                if (ddz.id == player.Nick)
                                {
                                    this.player.Score += ddz.score;
                                    break;
                                }
                            }

                        }

                        if (this.ddzdata.operationTimeoutSeconds > 0 && this.ddzdata.operationTimeoutSeconds < 100)
                            await this.operationTimeoutTimer();
                    }
                    else if (element.GetString() == "chanmsg")
                    {
                        currentChannel.msgs.Insert(0, msg);
                        if (currentChannel.msgs.Count > 120)
                            currentChannel.msgs.RemoveRange(100, 20);
                    }

                }
                Console.WriteLine("onmessage_end");
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine($"onmessage_ex_{ex.Message}_{msgobjer}");
        }

    }

　　在html5版中有使用setTimeout来刷新用户的等待操作时间，我们可以通过一个折中方法实现

    private CancellationTokenSource timernnnxx { get; set; }

    //js setTimeout
    private async Task setTimeout(Func<Task> action, int time)
    {
        try
        {
            timernnnxx = new CancellationTokenSource();
            await Task.Delay(time, timernnnxx.Token);
            await action?.Invoke();
        }
        catch (Exception ex)
        {
            Console.WriteLine($"setTimeout_{ex.Message}");
        }

    }
    private async Task operationTimeoutTimer()
    {
        Console.WriteLine("operationTimeoutTimer_" + this.ddzdata.operationTimeoutSeconds);
        if (timernnnxx != null)
        {
            timernnnxx.Cancel(false);
            Console.WriteLine("operationTimeoutTimer 取消");
        }
        this.ddzdata.operationTimeoutSeconds--;
        StateHasChanged();
        if (this.ddzdata.operationTimeoutSeconds > 0)
        {
            await setTimeout(this.operationTimeoutTimer, 1000);
        }
    }

　　其他组件相关如数据绑定，事件处理，组件参数等等推荐直接看文档。

　　浏览器下载的部分资源如下

Blazor Wasm