MAUI 实现前后端分离开发

内容纲要

背景

最先采用的是 Maui + Blazor 开发，使用社区热度比较高的 Blazor UI 框架。

可是开发进行过程中， Maui 巨多坑，Blazor UI 框架也是巨多坑，使用 Blazor UI 写的页面和样式，过不了设计师和产品经理的是法眼。

最终决定使用原生前端结合，生成静态内容放到 Maui 中，然后将两者结合起来打包发布。

先搞前端

对于前端来说，按照正常的开发模式就行，不对对前端的代码产生污染。

可以使用 VS 创建前端项目，将其放到解决方案中，也可以单独创建一个目录，将前端代码放到里面。

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创建 MAUI Blazor 项目

创建 MAUI Blazor 项目，然后解决方案如下所示：

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首先将 wwwroot/css/app.css 文件移出来，放到 wwwroot中，然后新建一个 app.js 也是放到 wwwroot 中。

将 app.css 文件中的内容删除与 Blazor 无关的内容，只保留以下内容：

#blazor-error-ui {
    background: lightyellow;
    bottom: 0;
    box-shadow: 0 -1px 2px rgba(0, 0, 0, 0.2);
    display: none;
    left: 0;
    padding: 0.6rem 1.25rem 0.7rem 1.25rem;
    position: fixed;
    width: 100%;
    z-index: 1000;
}

#blazor-error-ui .dismiss {
    cursor: pointer;
    position: absolute;
    right: 0.75rem;
    top: 0.5rem;
}

.blazor-error-boundary {
    background: url(data:image/svg+xml;base64,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) no-repeat 1rem/1.8rem, #b32121;
    padding: 1rem 1rem 1rem 3.7rem;
    color: white;
}

.blazor-error-boundary::after {
    content: "An error has occurred."
}

.status-bar-safe-area {
    display: none;
}

@supports (-webkit-touch-callout: none) {
    .status-bar-safe-area {
        display: flex;
        position: sticky;
        top: 0;
        height: env(safe-area-inset-top);
        background-color: #f7f7f7;
        width: 100%;
        z-index: 1;
    }

    .flex-column, .navbar-brand {
        padding-left: env(safe-area-inset-left);
    }
}

接着，将以下代码放到 app.js 中，用于动态导入前端生成的 css 文件。

function InitializeCss(name) {
    document.getElementById("app-css").innerHTML = '<link rel="stylesheet" href="' + name + '">';
}

然后删除 js、css 目录。

剩下的文件如图所示：

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然后修改 index.html，内容如下：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no, viewport-fit=cover" />
    <title>MauiApp3</title>
    <base href="/" />
    <link href="/app.css" rel="stylesheet" />
</head>

<body>
    <div id="app-css"></div>
    <div class="status-bar-safe-area"></div>
    <div id="app">Loading...</div>

    <div id="blazor-error-ui">
        An unhandled error has occurred.
        <a href="" class="reload">Reload</a>
        <a class="dismiss">🗙</a>
    </div>
    <script src="app.js"></script>
    <script src="_framework/blazor.webview.js" autostart="false"></script>

</body>

</html>

增加的 <div id="app-css"></div>，用于动态加载 css 文件。

其它内容基本不变。

打开 MainLayout.razor，这里负责动态加载前端文件，其内容如下：

@using MauiApp3.Data
@inherits LayoutComponentBase

@code {

    #region static fields

    private static readonly string[] css;
    private static readonly string[] js;

    #endregion

    #region instance fields

    [Inject]
    private IJSRuntime JS { get; set; }

    #endregion

    static MainLayout()
    {
        var path = Windows.ApplicationModel.Package.Current.InstalledLocation.Path;

        if (Directory.Exists(Path.Combine(path, "wwwroot", "css")))
        {
            var cssList = Directory.GetFiles(Path.Combine(path, "wwwroot", "css"))
            .Where(x => x.EndsWith(".css"))
            .Select(x => Path.GetFileName(x)).ToArray();
            css = cssList;
        }
        else css = Array.Empty<string>();

        if (Directory.Exists(Path.Combine(path, "wwwroot", "js")))
        {
            var jsList = Directory.GetFiles(Path.Combine(path, "wwwroot", "js"))
                .Where(x => x.EndsWith(".js"))
                .Select(x => Path.GetFileName(x)).ToArray();
            js = jsList;
        }
        else js = Array.Empty<string>();
    }

    protected override async Task OnInitializedAsync()
    {
        await Task.CompletedTask;
    }

    protected override async Task OnAfterRenderAsync(bool firstRender)
    {
        if (firstRender)
        {
            foreach (var item in css)
            {
                await JS.InvokeVoidAsync("InitializeCss", $"css/{item}");
            }

            foreach (var item in js)
            {
                await JS.InvokeAsync<IJSObjectReference>("import", $"/js/{item}");
            }
        }
    }
}

然后为了能够将前端生成的内容自动复制到 Maui 中，可以设置脚本，在 Maui 的 .csproj 中，增加以下内容：

    <Target Name="ClientBuild"   BeforeTargets="BeforeBuild">
        <Exec WorkingDirectory="../vueproject1" Command="npm install" />
        <Exec WorkingDirectory="../vueproject1" Command="npm run build" />
        <Exec WorkingDirectory="../vueproject1" Command="DEL "dist\index.html"" />
        <Exec WorkingDirectory="./" Command="RMDIR /s/q "css"" />
        <Exec WorkingDirectory="./" Command="RMDIR /s/q "js"" />
        <Exec WorkingDirectory="../vueproject1" Command="Xcopy "dist" "../MauiApp3/wwwroot"  /E/C/I/Y" />
        <Exec WorkingDirectory="./" Command="RMDIR /s/q "$(LayoutDir)""/>
    </Target>

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