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php 实现依赖注入

2026-03-13 09:38:07PHP

依赖注入的概念

依赖注入（Dependency Injection, DI）是一种设计模式，用于解耦组件之间的依赖关系。通过将依赖对象从外部注入，而不是在类内部直接创建，可以提高代码的可测试性和可维护性。

手动实现依赖注入

通过构造函数或方法参数显式传递依赖对象。

class DatabaseConnection {
    public function connect() {
        return "Database connected";
    }
}

class UserService {
    private $db;

    public function __construct(DatabaseConnection $db) {
        $this->db = $db;
    }

    public function getUser() {
        return $this->db->connect() . " - User data";
    }
}

$db = new DatabaseConnection();
$userService = new UserService($db);
echo $userService->getUser();

使用容器实现依赖注入

依赖注入容器（DIC）可以自动管理依赖关系的创建和注入。

class Container {
    private $bindings = [];

    public function bind($abstract, $concrete) {
        $this->bindings[$abstract] = $concrete;
    }

    public function resolve($abstract) {
        if (isset($this->bindings[$abstract])) {
            $concrete = $this->bindings[$abstract];
            if (is_callable($concrete)) {
                return $concrete($this);
            }
            return $this->resolve($concrete);
        }
        return new $abstract();
    }
}

$container = new Container();
$container->bind(DatabaseConnection::class, function() {
    return new DatabaseConnection();
});

$userService = $container->resolve(UserService::class);
echo $userService->getUser();

使用第三方库

PHP生态中有多个成熟的DI容器库，例如：

PHP-DI

require_once 'vendor/autoload.php';
use DI\ContainerBuilder;

$builder = new ContainerBuilder();
$builder->addDefinitions([
    DatabaseConnection::class => DI\create(DatabaseConnection::class)
]);
$container = $builder->build();

$userService = $container->get(UserService::class);

Symfony DependencyInjection

php 实现依赖注入

use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Reference;

$container = new ContainerBuilder();
$container->register('db', DatabaseConnection::class);
$container->register('user.service', UserService::class)
    ->addArgument(new Reference('db'));

$userService = $container->get('user.service');