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php实现di

2026-02-28 13:10:49PHP

依赖注入（DI）实现方法

在PHP中实现依赖注入（Dependency Injection，DI）可以通过手动注入或使用容器两种方式完成。以下是具体实现方法：

手动依赖注入

通过构造函数或方法直接传递依赖对象，不依赖外部容器。

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

class UserRepository {
    private $db;

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

    public function getUsers() {
        return $this->db->connect() . " -> Fetching users";
    }
}

// 手动注入
$db = new DatabaseConnection();
$userRepo = new UserRepository($db);
echo $userRepo->getUsers();

使用DI容器

通过容器管理依赖关系，自动解析和注入依赖项。以下是简易容器实现：

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);
        }

        $reflector = new ReflectionClass($abstract);
        $constructor = $reflector->getConstructor();

        if (is_null($constructor)) {
            return new $abstract;
        }

        $parameters = $constructor->getParameters();
        $dependencies = array_map(
            function($param) {
                return $this->resolve($param->getClass()->name);
            },
            $parameters
        );

        return $reflector->newInstanceArgs($dependencies);
    }
}

// 使用容器
$container = new Container();
$container->bind(DatabaseConnection::class, DatabaseConnection::class);
$userRepo = $container->resolve(UserRepository::class);
echo $userRepo->getUsers();

使用现有DI库

推荐使用成熟的DI库如PHP-DI或Symfony DependencyInjection组件：

// 使用PHP-DI示例
require_once 'vendor/autoload.php';

use DI\ContainerBuilder;

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

$userRepo = $container->get(UserRepository::class);
echo $userRepo->getUsers();

接口绑定实践

通过接口绑定实现更松散的耦合：

interface DatabaseInterface {
    public function connect();
}

class MySQLConnection implements DatabaseInterface {
    public function connect() {
        return "MySQL connected";
    }
}

// 容器配置
$container->bind(DatabaseInterface::class, MySQLConnection::class);