Get CMS Block content by identifier in Magento 2.

You can get CMS Static Blocks collection by an identifier in Magento 2 by calling BlockRepositoryInterface interface.

Magento\Cms\Api\BlockRepositoryInterface used for getting CMS Static Blocks in Magento 2.

BlockRepositoryInterface is used when you need to fetch a collection of CMS Static blocks or get specific CMS static block data.

You need to instantiate BlockRepositoryInterface in __construct() method of Class.

I wil give you demo using Block Class,

Get CMS Static Block by identifier, You need to pass identifier in searchCriteriaBuilder addFilter() method,
Let’s assume CMS Static Block identifier is footer_links_block,

$searchCriteria = $this->searchCriteriaBuilder->addFilter(‘identifier’, ‘footer_links_block’,’eq’)->create();
We have used equal conditions, You can set any conditions as third parameter in above function as per your needs.

List of Conditions are, ‘eq’,’neq’,’like’,’nlike’,’in’,’nin’,’notnull’,’null’,’gt’,’lt’,’gteq’,’lteq’,’finset’

namespace Rbj\CmsBlock\Block;

class CmsBlock extends \Magento\Framework\View\Element\Template
    public function __construct(
        \Magento\Framework\View\Element\Template\Context $context,
        \Magento\Cms\Api\BlockRepositoryInterface $blockRepository,
        \Magento\Framework\Api\SearchCriteriaBuilder $searchCriteriaBuilder,
        array $data = []
    ) {
        $this->blockRepository = $blockRepository;
        $this->searchCriteriaBuilder = $searchCriteriaBuilder;
        parent::__construct($context, $data);

  	/* Get Cms Blocks Collection from store. */
    public function getCmsBlock() {
        $searchCriteria = $this->searchCriteriaBuilder->addFilter('identifier', 'footer_links_block','eq')->create();
        $cmsBlock = $this->blockRepository->getList($searchCriteria)->getItems();
        return $cmsBlock;

From Template file, You can access all the Static Block by an iterating loa op over a collection.

	$cmsBlocks = $block->getCmsBlock();
	foreach($cmsBlocks as $cmsBlock) {
	    echo $cmsBlock->getId(); // get Id
	    echo $cmsBlock->getTitle(); // get Title/name of CMS Static Block
        //echo "<pre>";print_r($cmsBlock->getData());

Based on above Code snippet you get all the Cms Static Blocks from store. You can also get specific Static Blocks based on your custom condition by refer link.