Yii - 依赖注入

• 

  简述

  DI（依赖注入）容器是一个知道如何实例化和配置对象的对象。Yii 通过 yii \di\Container 类提供 DI 容器。

  它支持以下类型的 DI -

  • Setter 和属性注入
  • PHP 可调用注入
  • 构造函数注入
  • 控制器动作注入

  DI 容器借助类型提示支持构造函数注入 -

  
  class Object1 {
     public function __construct(Object2 $object2) {
     }
  }
  $object1 = $container->get('Object1');
  // which is equivalent to the following:
  $object2 = new Object2;
  $object1 = new Object1($object2);
  

  通过配置支持属性和设置器注入 -

  
  <?php
     use yii\base\Object;
     class MyObject extends Object {
        public $var1;
        private $_var2;
        public function getVar2() {
           return $this->_var2;
        }
        public function setVar2(MyObject2 $var2) {
           $this->_var2 = $var2;
        }
     }
     $container->get('MyObject', [], [
        'var1' => $container->get('MyOtherObject'),
        'var2' => $container->get('MyObject2'),
     ]);
  ?>
  

  在 PHP 可调用注入的情况下，容器将使用已注册的 PHP 回调来构建类的新实例 -

  
  $container->set('Object1', function () {
     $object1 = new Object1(new Object2);
     return $object1;
  });
  $object1 = $container->get('Object1');
  

  控制器动作注入是一种 DI，其中使用类型提示声明依赖项。它对于保持 MVC 控制器纤薄轻巧纤薄很有用 -

  
  public function actionSendToAdmin(EmailValidator $validator, $email) {
     if ($validator->validate($email)) {
        // sending email
     }
  }
  

  您可以使用yii\db\Container::set()方法来注册依赖项 -

  
  <?php
     $container = new \yii\di\Container;
     // register a class name as is. This can be skipped.
     $container->set('yii\db\Connection');
     // register an alias name. You can use $container->get('MyObject')
     // to create an instance of Connection
     $container->set('MyObject', 'yii\db\Connection');
     // register an interface
     // When a class depends on the interface, the corresponding class
     // will be instantiated as the dependent object
     $container->set('yii\mail\MailInterface', 'yii\swiftmailer\Mailer');
     // register an alias name with class configuration
     // In this case, a "class" element is required to specify the class
     $container->set('db', [
        'class' => 'yii\db\Connection',
        'dsn' => 'mysql:host=127.0.0.1;dbname = helloworld',
        'username' => 'vladimir',
        'password' => '12345',
        'charset' => 'utf8',
     ]);
     // register a class with configuration. The configuration
     // will be applied when the class is instantiated by get()
     $container->set('yii\db\Connection', [
        'dsn' => 'mysql:host=127.0.0.1;dbname = helloworld',
        'username' => 'vladimir',
        'password' => '12345',
        'charset' => 'utf8',
     ]);
     // register a PHP callable
     // The callable will be executed each time when $container->get('db') is called
     $container->set('db', function ($container, $params, $config) {
        return new \yii\db\Connection($config);
     });
     // register a component instance
     // $container->get('pageCache') will return the same instance each time when it 
        //is called
     $container->set('pageCache', new FileCache);
  ?>
  

• 

  使用 DI

  第 1 步- 在components文件夹中创建一个名为MyInterface.php的文件，其中包含以下代码。

  
  <?php
     namespace app\components;
     interface MyInterface {
        public function test();
     }
  ?>
  

  第 2 步 - 在 components 文件夹中，创建两个文件。

  First.php -

  
  <?php
     namespace app\components;
     use app\components\MyInterface;
     class First implements MyInterface {
        public function test() {
           echo "First class <br>";
        }
     }
  ?>
  

  Second.php -

  
  <?php
     app\components;
     use app\components\MyInterface;
        class Second implements MyInterface {
        public function test() {
           echo "Second class <br>";
        }
     }
  ?>
  

  第 3 步- 现在，将 actionTestInterface 添加到SiteController。

  
  public function actionTestInterface() {
     $container = new \yii\di\Container();
     $container->set
        ("\app\components\MyInterface","\app\components\First");
     $obj = $container->get("\app\components\MyInterface");
     $obj->test(); // print "First class"
     $container->set
        ("\app\components\MyInterface","\app\components\Second");
     $obj = $container->get("\app\components\MyInterface");
     $obj->test(); // print "Second class"
  }
  

  第 4 步- 转到http://localhost:8080/index.php?r=site/test-interface您应该看到以下内容。

  

  这种方法很方便，因为我们可以在一个地方设置类，其他代码会自动使用新的类。