找不到类'Smalot \ PdfParser \ Parser'

I am trying to use Pdfparser library to parse a PDF file but I have some issues with classes inclusion.

I read the documentation but it doesn't works.

I use Windows and XAMPP.

• I created a directory in /xampp/htdocs/pdf_import
• I installed Composer and I've generated the /vendor/autoload.php in pdfparser-master/src
• I use the code example in documentation

Example:

<?php

require 'vendor/autoload.php';

// Parse pdf file and build necessary objects.
$parser = new \Smalot\PdfParser\Parser();
$pdf    = $parser->parseFile('document.pdf');

// Retrieve all pages from the pdf file.
$pages = $pdf->getPages();

// Loop over each page to extract text.
foreach ($pages as $page) {
    echo $page->getText();
}

When I run the php script I obtain this error:

Fatal error: Class 'Smalot\PdfParser\Parser' not found in C:\xampp\htdocs\pdf_import\pdfparser-master\src\import.php on line 8