依赖注入容器 PHP

Question

我最近了解到在我的 PHP 应用程序中使用依赖注入 (DI) 的优势。

但是，我仍然不确定如何为依赖项创建容器。之前，我使用框架中的容器，我想了解他在后面是如何做事并重现它。

例如：

来自 Zend 2 的容器。我知道容器使类动态化，他不必从一开始就知道它们，他检查他是否已经在他的注册表中拥有该类，如果他没有，他检查是否类存在，构造函数内部有什么参数并将其放入他自己的注册表中，以便下次可以从那里获取它，实际是动态地做所有事情并且它正在完成他自己的注册表，所以我们一旦实现就不必关心任何事情容器，因为他可以提供我们想要的任何课程，即使我们只是制作那个课程。

另外，如果我想为需要 B 和 B 需要 C 的 A 发送 getInstance，我知道他这样做是递归的，他去实例化 C，然后是 B，最后是 A。

所以我了解大局以及他应该做什么，但我不太确定如何实施。

Answer 1

您最好使用现有的依赖容器之一，例如 PHP-DI 或 Pimple。但是，如果您正在寻找更简单的解决方案，那么我已经实现了一个依赖容器，作为我在这里写的文章的一部分：http://software-architecture-php.blogspot.com/

这是容器的代码

    class Container implements \DecoupledApp\Interfaces\Container\ContainerInterface 
{
    /**
     * This function resolves the constructor arguments and creates an object
     * @param string $dataType
     * @return mixed An object
     */
    private function createObject($dataType)
    {
        if(!class_exists($dataType)) {
            throw new \Exception("$dataType class does not exist");
        }
        $reflectionClass = new \ReflectionClass($dataType);
        $constructor = $reflectionClass->getConstructor();
        $args = null;
        $obj = null;
        if($constructor !== null)
        {
            $block = new \phpDocumentor\Reflection\DocBlock($constructor);

            $tags = $block->getTagsByName("param");
            if(count($tags) > 0)
            {
                $args = array();
            }
            foreach($tags as $tag)
            {
                //resolve constructor parameters
                $args[] = $this->resolve($tag->getType());
            }
        }
        if($args !== null)
        {
            $obj = $reflectionClass->newInstanceArgs($args);
        }
        else
        {
            $obj = $reflectionClass->newInstanceArgs();
        }

        return $obj;
    }

    /**
     * Resolves the properities that have a type that is registered with the Container. 
     * @param mixed $obj
     */
    private function resolveProperties(&$obj)
    {
        $reflectionClass = new \ReflectionClass(get_class($obj));
        $props = $reflectionClass->getProperties();
        foreach($props as $prop)
        {
            $block = new \phpDocumentor\Reflection\DocBlock($prop);

            //This assumes that there is only one "var" tag.
            //If there are more than one, then only the first one will be considered.
            $tags = $block->getTagsByName("var");
            if(isset($tags[0]))
            {
                $value = $this->resolve($tags[0]->getType());

                if($value !== null)
                {
                    if($prop->isPublic()) {
                        $prop->setValue($obj, $value);
                    } else {
                        $setter = "set".ucfirst($prop->name);
                        if($reflectionClass->hasMethod($setter)) {
                            $rmeth = $reflectionClass->getMethod($setter);
                            if($rmeth->isPublic()){
                                $rmeth->invoke($obj, $value);
                            }
                        }
                    }
                }
            }
        }
    }

    /**
     * 
     * @param string $dataType
     * @return object|NULL If the $dataType is registered, the this function creates the corresponding object and returns it;
     * otherwise, this function returns null
     */
    public function resolve($dataType) 
    {
        $dataType = trim($dataType, "\\");
        $obj = null;
        if(isset($this->singletonRegistry[$dataType])) 
        {
            //TODO: check if the class exists
            $className = $this->singletonRegistry[$dataType];
            $obj = $className::getInstance();
        } 
        else if(isset($this->closureRegistry[$dataType]))
        {
            $obj = $this->closureRegistry[$dataType]();
        }
        else if(isset($this->typeRegistry[$dataType])) 
        {
            $obj = $this->createObject($this->typeRegistry[$dataType]);
        }

        if($obj !== null) 
        {
            //Now we need to resolve the object properties
            $this->resolveProperties($obj);
        }
        return $obj;
    }

    /**
     * @see \DecoupledApp\Interfaces\Container\ContainerInterface::make()
     */
    public function make($dataType)
    {
        $obj = $this->createObject($dataType);
        $this->resolveProperties($obj);
        return $obj;
    }

    /**
     *
     * @param Array $singletonRegistry
     * @param Array $typeRegistry
     * @param Array $closureRegistry
     */
    public function __construct($singletonRegistry, $typeRegistry, $closureRegistry) 
    {
        $this->singletonRegistry = $singletonRegistry;
        $this->typeRegistry = $typeRegistry;
        $this->closureRegistry = $closureRegistry;
    }

    /**
     * An array that stores the mappings of an interface to a concrete singleton class. 
     * The key/value pair corresond to the interface name/class name pair.
     * The interface and class names are all fully qualified (i.e., include the namespaces).
     * @var Array
     */
    private $singletonRegistry;

    /**
     * An array that stores the mappings of an interface to a concrete class. 
     * The key/value pair corresond to the interface name/class name pair.
     * The interface and class names are all fully qualified (i.e., include the namespaces).
     * @var Array
     */
    private $typeRegistry;

    /**
     * An array that stores the mappings of an interface to a closure that is used to create and return the concrete object.
     * The key/value pair corresond to the interface name/class name pair.
     * The interface and class names are all fully qualified (i.e., include the namespaces).
     * @var Array
     */
    private $closureRegistry;

}

上面的代码可以在这里找到：https://github.com/abdulla16/decoupled-app（在/Container文件夹下）

您可以将依赖项注册为单例、类型（每次实例化新对象时）或闭包（容器将调用您注册的函数，并且该函数应返回实例） .

例如，

$singletonRegistry = array();
$singletonRegistry["DecoupledApp\\Interfaces\\UnitOfWork\\UnitOfWorkInterface"] =
    "\\DecoupledApp\\UnitOfWork\\UnitOfWork";


$typeRegistry = array();
$typeRegistry["DecoupledApp\\Interfaces\\DataModel\\Entities\\UserInterface"] = 
    "\\DecoupledApp\\DataModel\\Entities\\User";

$closureRegistry = array();
$closureRegistry["DecoupledApp\\Interfaces\\DataModel\\Repositories\\UserRepositoryInterface"] = 
    function() {
        global $entityManager;
        return $entityManager->getRepository("\\DecoupledApp\\DataModel\\Entities\\User");
    };

$container = new \DecoupledApp\Container\Container($singletonRegistry, $typeRegistry, $closureRegistry);

此容器解析类的属性以及构造函数参数。

Answer 2

我已经完成了一个非常简单的 IoC 类，它可以按预期工作。我研究了 IoC 和 DI 模式，尤其是在阅读 this answer 之后。如果有问题或有任何问题，请告诉我。

<?php

class Dependency {
 protected $object = null;
 protected $blueprint = null;

 /**
  * @param $instance callable The callable passed to the IoC object.
  */
 public function __construct($instance) {
   if (!is_object($instance)) {
     throw new InvalidArgumentException("Received argument should be object.");
   }

   $this->blueprint = $instance;
 }

 /**
  * (Magic function)
  *
  * This function serves as man-in-the-middle for method calls,
  * the if statement there serves for lazy loading the objects
  * (They get created whenever you call the first method and
  * all later calls use the same instance).
  *
  * This could allow laziest possible object definitions, like
  * adding annotation parsing functionality which can extract everything during
  * the call to the method. once the object is created it can get the annotations
  * for the method, automatically resolve its dependencies and satisfy them,
  * if possible or throw an error.
  *
  * all arguments passed to the method get passed to the method
  * of the actual code dependency.
  *
  * @param $name string The method name to invoke
  * @param $args array The array of arguments which will be passed
  *               to the call of the method
  *
  * @return mixed the result of the called method.
  */
 public function __call($name, $args = array())
 {
   if (is_null($this->object)) {
     $this->object = call_user_func($this->blueprint);
   }

   return call_user_func_array(array($this->object, $name), $args);
 }
}

/*
 * If the object implements \ArrayAccess you could
 * have easier access to the dependencies.
 *
 */
class IoC {
  protected $immutable = array(); // Holds aliases for write-protected definitions
  protected $container = array(); // Holds all the definitions

  /**
   * @param $alias string Alias to access the definition
   * @param $callback callable The calback which constructs the dependency
   * @param $immutable boolean Can the definition be overriden?
   */
  public function register ($alias, $callback, $immutable = false) {
    if (in_array($alias, $this->immutable)) {
      return false;
    }

    if ($immutable) {
      $this->immutable[] = $alias;
    }

    $this->container[$alias] = new Dependency($callback);
    return $this;
  }

  public function get ($alias) {
    if (!array_key_exists($alias, $this->container)) {
      return null;
    }

    return $this->container[$alias];
  }
}

class FooBar {
  public function say()
  {
    return 'I say: ';
  }

  public function hello()
  {
    return 'Hello';
  }

  public function world()
  {
    return ', World!';
  }
}

class Baz {
  protected $argument;

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

  public function working()
  {
    return $this->argument->say() . 'Yep!';
  }
}

/**
 * Define dependencies
 */

$dic = new IoC;
$dic->register('greeter', function () {
  return new FooBar();
});

$dic->register('status', function () use ($dic) {
  return new Baz($dic->get('greeter'));
});

/**
 * Real Usage
 */
$greeter = $dic->get('greeter');

print $greeter->say() . ' ' . $greeter->hello() . ' ' . $greeter->world() . PHP_EOL . '<br />';

$status = $dic->get('status');
print $status->working();
?>

我认为代码是不言自明的，但如果有不清楚的地方请告诉我

Answer 3

因为我没有找到任何接近我想要的东西，所以我尝试自己实现一个容器，我想听听一些关于外观的意见，因为一个月前我已经开始学习 php 和 oop反馈对我来说非常重要，因为我知道我有很多东西要学，所以请随意欺负我的代码:))

<!DOCTYPE html>
<!--
To change this license header, choose License Headers in Project Properties.
To change this template file, choose Tools | Templates
and open the template in the editor.
-->
<?php

class ioc
{
    private $defs;
    static $instance;
    private $reflection;
    private function __construct()
    {
        $defs       = array();
        $reflection = array();
    }
    private function __clone()
    {
        ;
    }
    public static function getInstance()
    {
        if (!self::$instance) {
            self::$instance = new ioc();
        }
        return self::$instance;
    }
    public function getInstanceOf($class)
    {
        if (is_array($this->defs) && key_exists($class, $this->defs)) {
            if (is_object($this->defs[$class])) {
                return $this->defs[$class];
            }
        } else {
            if (class_exists($class)) {
                if (is_array($this->reflection) && key_exists($class, $this->reflection)) {
                    $reflection = $this->reflection[$class];
                } else {
                    $reflection               = new ReflectionClass($class);
                    $this->reflection[$class] = $reflection;

                }
                $constructor = $reflection->getConstructor();
                if ($constructor) {
                    $params = $constructor->getParameters();
                    if ($params) {
                        foreach ($params as $param) {
                            $obj[] = $this->getInstanceOf($param->getName());

                        }
                        $class_instance = $reflection->newInstanceArgs($obj);
                        $this->register($class, $class_instance);
                        return $class_instance;
                    }
                }
                if (!$constructor || !$params) {
                    $class_instance = new $class;
                    $this->register($class, $class_instance);
                    return $class_instance;
                }

            }
        }
    }
    public function register($key, $class)
    {
        $this->defs[$key] = $class;
    }

}
?>