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提供对它 yii\di\Container 类来提供 DI 容器。
它支持以下几种注入方式 -
-
Setter方法和属性注入
-
PHP可调用注入
-
构造函数注入
-
控制器动作注入
依赖注入(DI)容器支持构造器使用类型提示的帮助来注入 -
class Object1 {
public function __construct(Object2 $object2) {
}
}
$object1 = $container->get('Object1');
// which is equivalent to the following:
$object2 = new Object2;
$object1 = new Object1($object2);
属性和 setter 注入需要通过配置支持 -
<?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'),
]);
?>
在调用PHP注入的案例中，容器将使用注册的 PHP 回调构建类的新实例 -
$container->set('Object1', function () {
$object1 = new Object1(new Object2);
return $object1;
});
$object1 = $container->get('Object1');
控制器操作注入是一种依赖注入(DI)类型，在这里依赖声明使用类型提示。这是有助于保持 MVC 控制器的超轻量级 -
public function actionSendToAdmin(EmailValidator $validator, $email) {
if ($validator->validate($email)) {
// sending email
}
}
可以使用 yii\db\Container::set() 方法来注册依赖 -
<?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 = mystudy',
'username' => 'root',
'password' => '',
'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);
?>
使用依赖注入(DI)
第1步 - 在 components 文件夹中创建一个 MyInterface.php 的文件，并使用下面的代码。
<?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
namespace app\components;
use app\components\MyInterface;
class Second implements MyInterface {
public function test() {
echo "Second class <br>";
}
}
?>
第3步 - 现在，添加一个 actionTestInterface 到控制器 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 - 在浏览器打开URL地址：http://localhost:8080/index.php?r=site/test-interface ，会看到输出如下图所示。
这种方法很方便，因为我们可以在一个地方设置类，而且其他代码将自动使用新类。