QRCodeGenerator.java

package src;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.WriterException;
import com.google.zxing.qrcode.QRCodeWriter;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;



public class QRCodeGenerator {

    public static void main(String[] args) throws WriterException, IOException {
        var qrCodeData = "hola";
        var filePath = "qr.png";
        var size = 250;
        var fileType = "png";
        var qrFile = new File(filePath);

        var hintMap = new HashMap<EncodeHintType, Object>();
        hintMap.put(EncodeHintType.CHARACTER_SET, "UTF-8");

        var qrCodeWriter = new QRCodeWriter();
        var byteMatrix = qrCodeWriter.encode(qrCodeData, BarcodeFormat.QR_CODE, size, size, hintMap);
        var matrixWidth = byteMatrix.getWidth();
        var image = new BufferedImage(matrixWidth, matrixWidth, BufferedImage.TYPE_INT_RGB);
        image.createGraphics();

        var graphics = (Graphics2D) image.getGraphics();
        graphics.setColor(Color.WHITE);
        graphics.fillRect(0, 0, matrixWidth, matrixWidth);
        graphics.setColor(Color.BLACK);

        for (int i = 0; i < matrixWidth; i++) {
            for (int j = 0; j < matrixWidth; j++) {
                if (byteMatrix.get(i, j)) {
                    graphics.fillRect(i, j, 1, 1);
                }
            }
        }

        ImageIO.write(image, fileType, qrFile);
    }
}