是否可以将接口(interface)绑定(bind)到 Laravel Controller 中的实现？类似于以下非常粗略的示例:

if($property->param == 1){
    $mailSourceData = bind('MailInterface', 'gmailProviderRepo')
{
else if($property->param == 2){
    $mailSourceData = bind('MailInterface', 'yahooProviderRepo')
}

$mailSourceData->sendMail($emailBody);

这不适用于服务提供者中的上下文绑定(bind)，因为那时我不知道我需要哪个接口(interface)实现，而且“$property”对服务提供者不可用。

最佳答案

你可以使用 Laravel 的服务容器:

https://laravel.com/docs/5.0/container

我认为单例可能是您的选择:

$this->app->singleton('FooBar', function($app)
{
    return new FooBar($app['SomethingElse']);
});

您可以使用任何您想要的键，不需要是接口(interface)或类名，即使它是值得推荐的。

然后你可以这样调用它:

$fooBar = $this->app->make('FooBar');

要自动加载它以便始终可以访问，您可以使用服务提供商:

https://laravel.com/docs/5.6/providers

可以查看原邮件服务商是如何设置的，复制一些思路:

https://github.com/laravel/framework/blob/5.6/src/Illuminate/Mail/MailServiceProvider.php

默认的邮件服务提供商是:

/**
 * Register the Illuminate mailer instance.
 *
 * @return void
 */
protected function registerIlluminateMailer()
{
    $this->app->singleton('mailer', function ($app) {
        $config = $app->make('config')->get('mail');

        // Once we have create the mailer instance, we will set a container instance
        // on the mailer. This allows us to resolve mailer classes via containers
        // for maximum testability on said classes instead of passing Closures.
        $mailer = new Mailer(
            $app['view'], $app['swift.mailer'], $app['events']
        );

        if ($app->bound('queue')) {
            $mailer->setQueue($app['queue']);
        }

        // Next we will set all of the global addresses on this mailer, which allows
        // for easy unification of all "from" addresses as well as easy debugging
        // of sent messages since they get be sent into a single email address.
        foreach (['from', 'reply_to', 'to'] as $type) {
            $this->setGlobalAddress($mailer, $config, $type);
        }

        return $mailer;
    });
}

它使用单例 $app['swift.mailer']，创建为:

/**
 * Register the Swift Mailer instance.
 *
 * @return void
 */
public function registerSwiftMailer()
{
    $this->registerSwiftTransport();

    // Once we have the transporter registered, we will register the actual Swift
    // mailer instance, passing in the transport instances, which allows us to
    // override this transporter instances during app start-up if necessary.
    $this->app->singleton('swift.mailer', function ($app) {
        return new Swift_Mailer($app['swift.transport']->driver());
    });
}

这个使用 $app['swift.transport'] 创建:

/**
 * Register the Swift Transport instance.
 *
 * @return void
 */
protected function registerSwiftTransport()
{
    $this->app->singleton('swift.transport', function ($app) {
        return new TransportManager($app);
    });
}

您可以在此处查看 TransportManager 的代码:

https://github.com/laravel/framework/blob/5.6/src/Illuminate/Mail/TransportManager.php

它使用默认驱动程序，因为没有其他驱动程序传递给方法 driver()。

重用此代码可能很有趣，但它从配置中获取值，并且除非我们覆盖配置(在这种情况下根本不推荐!)，否则无法传递其他值!

所以剩下的唯一选择就是脏复制粘贴。

您可以创建一个新的 TransportManager 来支持不同的驱动程序，但这会使它过于复杂，我想现在只支持 smtp 驱动程序就足够了。

您的自定义邮件服务提供商可能是这样的:

    <?php

namespace App\Providers;

use Swift_Mailer;
use Illuminate\Mail\Mailer;
use Illuminate\Support\Arr;
use Illuminate\Support\Str;
use Illuminate\Support\ServiceProvider;
use Swift_SmtpTransport as SmtpTransport;

class MultipleMailServiceProvider extends ServiceProvider
{
    /**
     * Register any application services.
     *
     * @return void
     */
    public function register()
    {
        $this->registerMultipleMailer();
    }

    /**
     * Register the Illuminate mailer instance.
     *
     * @return void
     */
    protected function registerMultipleMailer()
    {
        foreach ($this->app->make('config')->get('mail.multiple') as $key => $config) {
            $this->app->singleton($key, function ($app) use ($config) {
                // Once we have create the mailer instance, we will set a container instance
                // on the mailer. This allows us to resolve mailer classes via containers
                // for maximum testability on said classes instead of passing Closures.
                $mailer = new Mailer(
                    $app['view'], new Swift_Mailer($this->createSmtpDriver($config)), $app['events']
                );

                // Next we will set all of the global addresses on this mailer, which allows
                // for easy unification of all "from" addresses as well as easy debugging
                // of sent messages since they get be sent into a single email address.
                foreach (['from', 'reply_to', 'to'] as $type) {
                    $this->setGlobalAddress($mailer, $config, $type);
                }

                return $mailer;
            });
        }
    }

    /**
     * Set a global address on the mailer by type.
     *
     * @param  \Illuminate\Mail\Mailer  $mailer
     * @param  array  $config
     * @param  string  $type
     * @return void
     */
    protected function setGlobalAddress($mailer, array $config, $type)
    {
        $address = Arr::get($config, $type);

        if (is_array($address) && isset($address['address'])) {
            $mailer->{'always'.Str::studly($type)}($address['address'], $address['name']);
        }
    }

    /**
     * Create an instance of the SMTP Swift Transport driver.
     *
     * @param array $config
     *
     * @return \Swift_SmtpTransport
     */
    protected function createSmtpDriver($config)
    {
        // The Swift SMTP transport instance will allow us to use any SMTP backend
        // for delivering mail such as Sendgrid, Amazon SES, or a custom server
        // a developer has available. We will just pass this configured host.
        $transport = new SmtpTransport($config['host'], $config['port']);

        if (isset($config['encryption'])) {
            $transport->setEncryption($config['encryption']);
        }

        // Once we have the transport we will check for the presence of a username
        // and password. If we have it we will set the credentials on the Swift
        // transporter instance so that we'll properly authenticate delivery.
        if (isset($config['username'])) {
            $transport->setUsername($config['username']);

            $transport->setPassword($config['password']);
        }

        // Next we will set any stream context options specified for the transport
        // and then return it. The option is not required any may not be inside
        // the configuration array at all so we'll verify that before adding.
        if (isset($config['stream'])) {
            $transport->setStreamOptions($config['stream']);
        }

        return $transport;
    }

    /**
     * Get the services provided by the provider.
     *
     * @return array
     */
    public function provides()
    {
        return array_keys($this->app->make('config')->get('mail.multiple'));
    }
}

然后您可能需要将数据添加到您的 mail.php 配置文件(或另一个配置文件)中，例如:

'multiple' => [
    'mailer.gmail' => [
        'host'       => env('MAIL_GAMIL_HOST', 'smtp.mailgun.org'),
        'port'       => env('MAIL_GAMIL_PORT', 587),
        'from'       => [
            'address' => env('MAIL_GAMIL_FROM_ADDRESS', 'hello@example.com'),
            'name'    => env('MAIL_GAMIL_FROM_NAME', 'Example'),
        ],
        'encryption' => env('MAIL_GAMIL_ENCRYPTION', 'tls'),
        'username'   => env('MAIL_GAMIL_USERNAME'),
        'password'   => env('MAIL_GAMIL_PASSWORD'),
    ],
    'mailer.yahoo' => [
        'host'       => env('MAIL_YAHOO_HOST', 'smtp.mailgun.org'),
        'port'       => env('MAIL_YAHOO_PORT', 587),
        'from'       => [
            'address' => env('MAIL_YAHOO_FROM_ADDRESS', 'hello@example.com'),
            'name'    => env('MAIL_YAHOO_FROM_NAME', 'Example'),
        ],
        'encryption' => env('MAIL_YAHOO_ENCRYPTION', 'tls'),
        'username'   => env('MAIL_YAHOO_USERNAME'),
        'password'   => env('MAIL_YAHOO_PASSWORD'),
    ],
],

不要忘记注册您的服务提供商:

https://laravel.com/docs/5.6/providers#registering-providers

'providers' => [
    // Other Service Providers

    App\Providers\MultipleMailServiceProvider::class,
],

然后，一旦服务提供商在服务容器中定义了单例，您就可以通过多种方式构建和加载创建的单例。一种方法是:

    switch ($property->param) {
        case 1:
            $mailSourceData = app('mailer.gmail');
            break;
        case 2:
            $mailSourceData = app('mailer.yahoo');
            break;
        default:
            throw new \InvalidArgumentException('Invalid property param');
    }

    $mailSourceData->sendMail($emailBody);

您甚至可以创建 Facedes 和别名...

https://laravel.com/docs/5.6/facades

当然，这里和那里可以进行一些可能的改进，但这只是概念验证。

关于php - Controller 中的 Laravel 绑定(bind)接口(interface)，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/49414326/