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关于Lumen / Laravel .env 文件中的环境变量是如何生效的
.env 文件包含默认环境变量,我们还可自定义其他任何有效的变量,并可通过 调用 env() 或 $_SERVER 或 $_ENV 来获取该变量。那么env()是如何加载到这些变量的呢?在Lumen的vendor/laravel/lumen-framework/src/helpers.php中,我们可以发现env函数是这样被定义的:
if (! function_exists(‘env‘)) { /** * Gets the value of an environment variable. Supports boolean, empty and null. * * @param string $key * @param mixed $default * @return mixed */ function env($key, $default = null) { $value = http://www.mamicode.com/getenv($key);>if ($value === false) { return value($default); } switch (strtolower($value)) { case ‘true‘: case ‘(true)‘: return true; case ‘false‘: case ‘(false)‘: return false; case ‘empty‘: case ‘(empty)‘: return ‘‘; case ‘null‘: case ‘(null)‘: return; } if (Str::startsWith($value, ‘"‘) && Str::endsWith($value, ‘"‘)) { return substr($value, 1, -1); } return $value; } }
可见,env函数中调用了 getenv() 来读取环境变量。我们又知道getenv()是PHP原生提供可读取 $_SERVER 或 $_ENV 全局变量的函数API,那么问题来了,.env文件中的环境变量又是如何变成 $_SERVER 或 $_ENV 变量的一部分的呢?vlucas/phpdotenv 就是这个幕后功臣,在Lumen 或 Laravel 的vendor下可以找到她,如果要单独下载她,去这里 :https://github.com/vlucas/phpdotenv 。
PHP dotenv 她是什么?
Loads environment variables from .env to getenv(), $_ENV and $_SERVER automagically. This is a PHP version of the original Ruby dotenv.
Why .env?
You should never store sensitive credentials in your code. Storing configuration in the environment is one of the tenets of a twelve-factor app. Anything that is likely to change between deployment environments – such as database credentials or credentials for 3rd party services – should be extracted from the code into environment variables. Basically, a .env file is an easy way to load custom configuration variables that your application needs without having to modify .htaccess files or Apache/nginx virtual hosts. This means you won‘t have to edit any files outside the project, and all the environment variables are always set no matter how you run your project - Apache, Nginx, CLI, and even PHP 5.4‘s built-in webserver. It‘s WAY easier than all the other ways you know of to set environment variables, and you‘re going to love it. . NO editing virtual hosts in Apache or Nginx . NO adding php_value flags to .htaccess files . EASY portability and sharing of required ENV values . COMPATIBLE with PHP‘s built-in web server and CLI runner
关于Lumen / Laravel .env 文件中的环境变量是如何生效的
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