DI(依賴注入)容器是一個知道如何實例化和配置對象的對象。 Yii提供對它 yii\di\Container 類來提供 DI 容器。
它支持以下幾種注入方式 -
-
Setter方法和屬性注入
-
PHP可調用注入
-
構造函數注入
-
控制器動作注入
依賴注入(DI)容器支持構造器使用類型提示的幫助來注入 -
class Object1 {
public function __construct(Object2 $object2) {
}
}
$object1 = $container->get('Object1');
// which is equivalent to the following:
$object2 = new Object2;
$object1 = new Object1($object2);
屬性和 setter 注入需要通過配置支持 -
<?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'),
]);
?>
在調用PHP注入的案例中，容器將使用註冊的 PHP 回調構建類的新實例 -
$container->set('Object1', function () {
$object1 = new Object1(new Object2);
return $object1;
});
$object1 = $container->get('Object1');
控制器操作注入是一種依賴注入(DI)類型，在這裏依賴聲明使用類型提示。這是有助於保持 MVC 控制器的超羽量級 -
public function actionSendToAdmin(EmailValidator $validator, $email) {
if ($validator->validate($email)) {
// sending email
}
}
可以使用 yii\db\Container::set() 方法來註冊依賴 -
<?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);
?>
使用依賴注入(DI)
第1步 - 在 components 檔夾中創建一個 MyInterface.php 的檔，並使用下麵的代碼。
<?php
namespace app\components;
interface MyInterface {
public function test();
}
?>
第2步 - 在 components 檔夾中創建兩個檔。
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 - 現在，添加一個 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 - 在流覽器打開URL地址：http://localhost:8080/index.php?r=site/test-interface ，會看到輸出如下圖所示。
這種方法很方便，因為我們可以在一個地方設置類，而且其他代碼將自動使用新類。