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();
 }
}