what is proper way to get object manager, entity collection in magento2 api?

Question

How to get properly access to objectManager/entityCollection (products or categories for example) from custom API class ?

Should I use DI in constructor ?

Is this approach correct, or it breaks DI concept ?

<?php
    namespace Company\Module\Model;

    use Company\Module\Api\ModuleInterface;

    class Connector implements ModuleInterface
    {
        protected $_objectManager;

        public function __construct() {
            $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
            /** @var \Magento\Catalog\Model\ResourceModel\Product\Collection $productCollection */
            $this->_objectManager = $objectManager;
        }

       public function myMethod(){ 

            $productCollection = $this->_objectManager->create('Magento\Catalog\Model\ResourceModel\Product\Collection');
            /** Apply filters here */
            $productCollection->load();
       }

    }

Maybe someone can give the path to existing api in magento from which I can learn from ?

Answer 1

<?php
namespace Company\Module\Model;

use Company\Module\Api\ModuleInterface;

class Connector implements ModuleInterface
{
    protected $collectionFactory;

    public function __construct(
        \Magento\Catalog\Model\ResourceModel\Product\CollectionFactory $collectionFactory
    ) {
        $this->collectionFactory = $collectionFactory;
    }

   public function myMethod(){ 

        $productCollection = $this->collectionFactory->create();
        /** Apply filters here */
        $productCollection->load();
   }
}