-> Here we have a dummy  JSON string. We will parse this JSON string and create a record for product and pricebookEntry in salesforce.

{  
   "title":"Shirt",
   "body_html":"This is product's description field",
   "variants":[  
      {  
         "price":"21.00",
      },
      {  
         "price":"24.00",
      }
   ]
}

-> For each variant we create a pricebookEntry in salesforce.

Here we have some JSONParser methods, which we are going to use to parse the above string.

1). JSON.createParser(jsonString) : Create new Parser

2). nextToken() : Locate  cursor to next token.

3). getCurrentToken() : To get the current token value.

4). getCurrentName() : To get the current field name.

5). nextValue() :Locate  cursor to next value.

6). getText() : To get the text value of the token.

1). Create a new pricebook (Name= ‘Demo’) from Pricebook>>New Pricebook>>Name= ‘Demo’>> Save.

2). Create an apex class jsonParserExample to parse the above string.

public class jsonParserExample {
	
    /**
    * Webkul Software.
    *
    * @category  Webkul
    * @author    Webkul
    * @copyright Copyright (c) 2010-2016 Webkul Software Private Limited (https://webkul.com)
    * @license   https://store.webkul.com/license.html
    */
   
    public jsonParserExample() {
        
        Pricebook2 pb = [SELECT Id FROM Pricebook2 WHERE isStandard = true limit 1]; // Get the standard Pricebook Id
        Pricebook2 cpb = [SELECT Id FROM Pricebook2 WHERE Name = 'Demo' limit 1];	 // Get the Custom Pricebook Id
        Product2 prod = new Product2();												 // New Product Object  	
        PricebookEntry pbe = new PricebookEntry();									 // New PricebookEntry Object
        List<PricebookEntry> list_pbe = new List<PricebookEntry>();                  // List of pricebook Entry
        
        // Dummy String to Parse
        
        String jsonString = '{\"title\":\"Shirt\",\"body_html\":\"This is products description field\",\"variants\":[{\"price\":\"21.00\"},{\"price\":\"24.00\"} ]}';
        
        // Create parser of dummy string
        
        JSONParser parser = JSON.createParser(jsonString);
        
        // Parsing of string
        
        while(parser.nextToken()!= null) {
            if(parser.getCurrentToken() == JSONToken.FIELD_NAME) {
                parser.nextValue();
                if(parser.getCurrentName() == 'title') {
                    prod.Name = parser.getText();
                } else if (parser.getCurrentName() == 'body_html') {
                    prod.Description = parser.getText();
                } else if (parser.getCurrentName() == 'variants') {
                    while(parser.nextToken()!= JSONToken.END_ARRAY) {
                        if(parser.getCurrentToken() == JSONToken.FIELD_NAME) {
                			parser.nextValue();
                            if(parser.getCurrentName() == 'price') {
                                pbe.UnitPrice = Decimal.valueOf(parser.getText());
                            }  
                        } else if(parser.getCurrentToken() == JSONToken.END_OBJECT) {
                            if(pbe.UnitPrice != null)
                            {
                             	list_pbe.add(pbe);   
                            }
                            pbe = new PricebookEntry();
                            continue;
                        } else if (parser.getCurrentToken() == JSONToken.START_OBJECT) {
                            continue;
                        }
                    }
                }
            }
        }
        
        // Create the Product in salesforce.
        if(prod.name != null) {
            try{
                insert prod;
            } catch(Exception ex) {
                system.debug(ex);
            }
        }
        
        // Create the pricebookEntry
        if(prod.Id != null && list_pbe.size()>0) {
            for(PricebookEntry p : list_pbe) {
                p.Product2Id = prod.Id;
            }
            list_pbe[0].Pricebook2Id = pb.Id;
            list_pbe[1].Pricebook2Id = cpb.Id;
            
            try{
                insert list_pbe;
            } catch(Exception ex) {
                system.debug(ex);
            }
        }
    }
}

2). Now open Execute Anonymous window (Ctrl+E) and execute the following code.

jsonParserExample a = new jsonParserExample();

Now, go to Product and check the created record.