构建和发布为 Web 应用

(例如)在典型的开发过程中,你可以在命令行使用 flutter run -d chrome 命令测试应用程序。这会构建出 debug 版本的应用。

During a typical development cycle, you test an app using flutter run -d chrome (for example) at the command line. This builds a debug version of your app.

本页面会帮助你构建 release 版本的应用,其囊括了如下主题:

This page helps you prepare a release version of your app and covers the following topics:

处理 Web 中的图片

Handling images on the web

Web 支持标准的 Image widge 来显示图片。但是,由于 Web 浏览器需要安全地运行不受信任的代码,因此与移动和桌面平台相比,图像处理方面存在某些限制。

The web supports the standard Image widget to display images. However, because web browsers are built to run untrusted code safely, there are certain limitations in what you can do with images compared to mobile and desktop platforms.

更多信息,请参阅 在 Web 中展示图片.

For more information, see Displaying images on the web.

选择 Web 渲染器

Choosing a web renderer

默认情况下,flutter buildflutter run 命令对 Web 渲染器使用 auto 参数。这意味着您的应用程序在移动浏览器上会与 HTML 渲染器一起运行,而在桌面浏览器上与 CanvasKit 一起运行。这是我们推荐的组合方式,能够针对每个平台特性优化。

By default, the flutter build and flutter run commands use the auto choice for the web renderer. This means that your app runs with the HTML renderer on mobile browsers and CanvasKit on desktop browsers. This is our recommended combination to optimize for the characteristics of each platform.

更多信息,请参阅 Web 渲染器.

For more information, see Web renderers.

混淆并压缩代码

Minification

当你创建了一个 release 版本时,便已经压缩了代码。

Minification is handled for you when you create a release build.

Debug 模式构建的 Web 应用没有被压缩,且 Tree-shaking 没有执行。

A debug build of a web app is not minified and tree shaking has not been performed.

Profile 模式构建的 Web 应用没有被压缩,但 Tree-shaking 执行了。

A profile build is not minified and tree shaking has been performed.

Release 模式构建的 Web 应用被压缩了,并且 Tree-shaking 执行了。

A release build is both minified and tree shaking has been performed.

构建用于发布的应用

Building the app for release

使用 flutter build web 命令构建应用程序以进行部署。你也可以通过使用 --web-renderer 自行选择渲染方式。(请查看 网页渲染器)这将生成包括资源的应用程序,并将文件放入项目的 /build/web 目录中。

Build the app for deployment using the flutter build web command. You can also choose which renderer to use by using the --web-renderer option (See Web renderers). This generates the app, including the assets, and places the files into the /build/web directory of the project.

一般的应用程序的 release 版本具有以下结构:

The release build of a simple app has the following structure:

/build/web
  assets
    AssetManifest.json
    FontManifest.json
    NOTICES
    fonts
      MaterialIcons-Regular.ttf
      <other font files>
    <image files>
  index.html
  main.dart.js
  main.dart.js.map

启动 Web 服务器(例如,python -m SimpleHTTPServer 8000,或使用 dhttpd package),然后打开 /build/web 目录。在浏览器中访问 localhost:8000(前文用 Python 启动的服务器)以查看应用程序的 release 版本。

Launch a web server (for example, python -m http.server 8000, or by using the dhttpd package), and open the /build/web directory. Navigate to localhost:8000 in your browser (given the python SimpleHTTPServer example) to view the release version of your app.

将 Flutter 应用内嵌到一个 HTML 页面里

Embedding a Flutter app into an HTML page

你可以使用 iframe 标签将 Flutter web 应用内嵌到一个网页里。请参照下面的例子,将 URL 替换成实际的地址:

You can embed a Flutter web app, as you would embed other content, in an iframe tag of an HTML file. In the following example, replace “URL” with the location of your HTML page:

<iframe src="URL"></iframe>

部署到 Web 端

Deploying to the web

等你准备好部署应用时,将 release 包上传到 Firebase、云或者是类似服务上:

When you are ready to deploy your app, upload the release bundle to Firebase, the cloud, or a similar service. Here are a few possibilities, but there are many others:

PWA Support

从 1.20 版开始,用于 Web 应用程序的 Flutter 模板包括了对可安装且具有离线功能的 PWA 应用程序所需的核心功能的支持。基于 Flutter 的 PWA 的安装方式与其他基于 Web 的 PWA 基本相同;由 manifest.json 提供的配置信息可以声明您的 Flutter 应用程序是 PWA,该文件可以在 web 目录中使用 Flutter create 命令生成。

As of release 1.20, the Flutter template for web apps includes support for the core features needed for an installable, offline-capable PWA app. Flutter-based PWAs can be installed in the same way as any other web-based PWA; the settings signaling that your Flutter app is a PWA are provided by manifest.json, which is produced by flutter create in the web directory.

对 PWA 的支持仍在进行中,因此,如果您发现不正确的地方,欢迎 给予我们反馈

PWA support remains a work in progress, so please give us feedback if you see something that doesn’t look right.