Hi Fabien,

I know this thread is old. However you find the below link useful if you want to access the data uploaded in static resource in your apex class and use it as test data or record creation/processing.

https://www.forcetree.com/2010/08/read-and-insert-records-from-csv-file.html
 

public class FileUploader 
{
    public string nameFile{get;set;}
    public Blob contentFile{get;set;}
    String[] filelines = new String[]{};
    List<Account> accstoupload;
    
    /***This function reads the CSV file and inserts records into the Account object. ***/
    public Pagereference ReadFile()
    {
        try{
                //Convert the uploaded file which is in BLOB format into a string
                nameFile =blobToString( contentFile,'ISO-8859-1');
                
                //Now sepatate every row of the excel file
                filelines = nameFile.split('\n');
                
                //Iterate through every line and create a Account record for each row
                accstoupload = new List<Account>();
                for (Integer i=1;i<filelines.size();i++)
                {
                    String[] inputvalues = new String[]{};
                    inputvalues = filelines[i].split(',');
                    
                    Account a = new Account();
                    a.Name = inputvalues[0];
                    a.ShippingStreet = inputvalues[1];       
                    a.ShippingCity = inputvalues[2];
                    a.ShippingState = inputvalues[3];
                    a.ShippingPostalCode = inputvalues[4];
                    a.ShippingCountry = inputvalues[5];
        
                    accstoupload.add(a);
                }
         }
         catch(Exception e){
                 ApexPages.Message errormsg = new ApexPages.Message(ApexPages.severity.ERROR,'An error has occured reading the CSV file'+e.getMessage());
                ApexPages.addMessage(errormsg);
         }       
        //Finally, insert the collected records
        try{
            insert accstoupload;
        }
        catch (Exception e)
        {
            ApexPages.Message errormsg = new ApexPages.Message(ApexPages.severity.ERROR,'An error has occured inserting the records'+e.getMessage());
            ApexPages.addMessage(errormsg);
        }    
        return null;
    }
   
   /**** This function sends back to the visualforce page the list of account records that were inserted ****/ 
    public List<Account> getuploadedAccounts()
    {
        if (accstoupload!= NULL)
            if (accstoupload.size() > 0)
                return accstoupload;
            else
                return null;                    
        else
            return null;
    }  
        /**
         This function convers the input CSV file in BLOB format into a string
        @param input    Blob data representing correct string in @inCharset encoding
        @param inCharset    encoding of the Blob data (for example 'ISO 8859-1')
     */
    public static String blobToString(Blob input, String inCharset){
        String hex = EncodingUtil.convertToHex(input);
        System.assertEquals(0, hex.length() & 1);
        final Integer bytesCount = hex.length() >> 1;
        String[] bytes = new String[bytesCount];
        for(Integer i = 0; i < bytesCount; ++i)
            bytes[i] =  hex.mid(i << 1, 2);
        return EncodingUtil.urlDecode('%' + String.join(bytes, '%'), inCharset);
    }         
}

Thanks,
Subhasini
Lightning Champion