在 PHP 7.4 中检测是否是移动设备，进而渲染不同的模板文件

1、由于前端，同一个页面，针对移动设备与桌面设备，是分别编写的页面。因此，需要在 PHP 7.4 中检测是否是移动设备，进而渲染不同的模板文件

2、参考：Mobile-Detect 。只能够使用 3.* 的最新版本，因为现在是使用的 PHP 7.4，其 4.* 的版本要求 PHP 8 以上的版本。。如图1

图1

3、Mobile Detect 是一个轻量级的 PHP 类，用于检测移动设备（包括平板电脑）。它使用 User-Agent 字符串结合特定的 HTTP 标头来检测移动环境。在页面的 Modules, plugins, ports -> Yii Framework，发现实现的 Yii2 扩展，都有 5 年左右没有更新，且依赖 “mobiledetect/mobiledetectlib”: “~2.8″。最终决定使用 “mobiledetect/mobiledetectlib”: “^3.74” 。配置 composer.json 。安装更新。如图2

图2

{
    "require": {
        "mobiledetect/mobiledetectlib": "^3.74"
    }
}

PS C:\wwwroot\object\src> composer install
Installing dependencies from lock file (including require-dev)
Verifying lock file contents can be installed on current platform.
Warning: The lock file is not up to date with the latest changes in composer.json. You may be getting outdated dependencies. It is recommended that you run `composer update` or `composer update <package name>`.
- Required package "mobiledetect/mobiledetectlib" is not present in the lock file.
This usually happens when composer files are incorrectly merged or the composer.json file is manually edited.
Read more about correctly resolving merge conflicts https://getcomposer.org/doc/articles/resolving-merge-conflicts.md
and prefer using the "require" command over editing the composer.json file directly https://getcomposer.org/doc/03-cli.md#require-r
PS C:\wwwroot\object\src> composer update mobiledetect/mobiledetectlib
Loading composer repositories with package information
Updating dependencies
Lock file operations: 1 install, 0 updates, 0 removals
  - Locking mobiledetect/mobiledetectlib (3.74.3)
Writing lock file
Installing dependencies from lock file (including require-dev)
Package operations: 1 install, 0 updates, 0 removals
  - Downloading mobiledetect/mobiledetectlib (3.74.3)
  - Installing mobiledetect/mobiledetectlib (3.74.3): Extracting archive
Package codeception/phpunit-wrapper is abandoned, you should avoid using it. No replacement was suggested.
Package sebastian/resource-operations is abandoned, you should avoid using it. No replacement was suggested.
Generating autoload files
59 packages you are using are looking for funding.
Use the `composer fund` command to find out more!
No security vulnerability advisories found.
PS C:\wwwroot\object\src>

4、然后在控制器中实现如下

use Detection\MobileDetect;

    /**
     * Displays homepage.
     *
     * @return mixed
     */
    public function actionIndex()
    {
        $detect = new MobileDetect();

        // $deviceType = ($detect->isMobile() ? ($detect->isTablet() ? 'tablet' : 'phone') : 'computer');
        if ($detect->isMobile()) {
            return $this->render('index_mobile');
        }

        return $this->render('index');
    }