Java QR code

1. QR Code Generator
2. Example to Create QR Code

QR Code Generator

Utilize google QR code generator …
Define the charset, format, and size.
Use MatrixToImageWriter to write a BitMatrix to BufferedImage, file or stream.

toBufferedImage method

public static BufferedImage toBufferedImage(BitMatrix matrix) {...}

encode method

public BitMatrix encode(String contents, BarcodeFormat format, int width, int height, Map<EncodeHintType, ?> hints) throws WriterException {...}

decode method

public Result decode(BinaryBitmap image, Map<DecodeHintType, ?> hints) throws NotFoundException {...}

Available BarcodeFormat

public enum BarcodeFormat {
    AZTEC,
    CODABAR,
    CODE_39,
    CODE_93,
    CODE_128,
    DATA_MATRIX,
    EAN_8,
    EAN_13,
    ITF,
    MAXICODE,
    PDF_417,
    QR_CODE,
    RSS_14,
    RSS_EXPANDED,
    UPC_A,
    UPC_E,
    UPC_EAN_EXTENSION;
}

An example goes here …

import com.google.zxing.*;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

import javax.imageio.ImageIO;
import java.*;

public class ZxingUtil {
    private static final Map<EncodeHintType, ErrorCorrectionLevel> encodeMap = new HashMap<EncodeHintType, ErrorCorrectionLevel>();
    private static final Map<DecodeHintType, ErrorCorrectionLevel> decodeMap = new HashMap<DecodeHintType, ErrorCorrectionLevel>();
    private static final String charset="UTF-8", format="png";
    private static final int size = 150;
    private ZxingUtil() {}

    /**
     * QR code encoder
     *
     * @param data data to be encoded
     * @throws WriterException
     * @throws IOException
     */
    public static BufferedImage createQRCode(String data)
        throws WriterException, IOException {
        return MatrixToImageWriter.toBufferedImage(new MultiFormatWriter()
                .encode(new String(data.getBytes(charset), charset),
                    BarcodeFormat.QR_CODE, size, size, encodeMap));
    }

    /**
     * QR code decoder
     *
     * @param image QR code image
     * @return
     * @throws FileNotFoundException
     * @throws IOException
     * @throws NotFoundException
     */
    public static String readQRCode(byte[] image)
        throws FileNotFoundException, IOException, NotFoundException {
        return new MultiFormatReader().decode(
            new BinaryBitmap(
                new HybridBinarizer(
                    new BufferedImageLuminanceSource(
                        ImageIO.read(new ByteArrayInputStream(image))))), decodeMap).getText();
    }

}

Example to Create QR Code

An example of using above method to create QR code …

/**
 * create user QR scan code
 * @param userScanCodeDTO
 * @return Optional<BufferedImage>
 */
public Optional<Image> createUserQRCode(@NotNull UserScanCodeDTO userScanCodeDTO) {
    log.debug("create user QR code : {}", userScanCodeDTO);
    return Optional.of(userScanCodeDTO)
        .map(usc -> {
            BufferedImage bufferedImage = null;
            try {
                bufferedImage = ZxingUtil.createQRCode(usc.getScanCode());
            } catch (Exception e) {
                log.debug(e.getMessage());
            }

            return bufferedImage;
        })
        .map(bufferedImage -> {
            ByteArrayOutputStream bs = new ByteArrayOutputStream();
            Image image = null;
            try {
                ImageIO.write(bufferedImage, "png", bs);
                 image = new Image()
                    .name(userScanCodeDTO.getScanCode())
                    .image(bs.toByteArray())
                    .imageContentType("image/png");
                bs.close();
            } catch (IOException e) {
                log.debug(e.getMessage());
            }
            return image;
        });
}

Ref:

ZXing 3.3.0 API

QR Code Generator

Example to Create QR Code