Handle file usage with drupal 8

Equivalent syntax Drupal 7 -> Drupal 8

Example :

//Add / Delete file usage

$entity_type = 'node';

$entity_id = 1;//Node ID

$fid = 1; // The file ID

$file = \Drupal\file\Entity\File::load($fid);

$file_usage = \Drupal::service('file.usage');

$file_usage->add($file, 'mymodule', $entity_type, $entity_id);

$list = $file_usage->listUsage($file);

$file_usage->delete($file, 'mymodule', $entity_type, $entity_id);

//Get usage of a file

$file = \Drupal\file\Entity\File::load($fid);

$file_usage = \Drupal::service('file.usage');

$list = $file_usage->listUsage($file);

Get Tempory Directory:

file_directory_temp();

See also :

file_managed_file_save_upload() , file_managed_file_submit(), file_unmanaged_*()

More : File usage is pluggable