一，引入依赖

       <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.3.3</version>
        </dependency>

二，生成二维码工具类

public class MatrixToImageWriter {
    private static final int BLACK = 0xFF000000;
    private static final int WHITE = 0xFFFFFFFF;

    private MatrixToImageWriter() {
    }

    public static BufferedImage toBufferedImage(BitMatrix matrix) {
        int width = matrix.getWidth();
        int height = matrix.getHeight();
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        for (int x = 0; x < width; x++) {
            for (int y = 0; y < height; y++) {
                image.setRGB(x, y, matrix.get(x, y) ? BLACK : WHITE);
            }
        }
        return image;
    }

    public static void writeToFile(BitMatrix matrix, String format, File file) throws 
  IOException {
        BufferedImage image = toBufferedImage(matrix);
        if (!ImageIO.write(image, format, file)) {
            throw new IOException("Could not write an image of format " + format + " to " + file);
        }
    }

}

三，生成二维码例子

    private void generatePicture(Device item) {

        try {
            String content = item.getQrCode();//二维码详情,手机扫描时,二维码显示的内容
            String path = "D:/pics/uploadFiles/qrUrl";// 二维码保存的路径
            String codeName = UUID.randomUUID().toString();// 二维码的图片名
            String imageType = "jpg";// 图片类型
            MultiFormatWriter multiFormatWriter = new MultiFormatWriter();
            Map<EncodeHintType, String> hints = new HashMap<EncodeHintType, String>();
            hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
            BitMatrix bitMatrix = multiFormatWriter.encode(content, BarcodeFormat.QR_CODE, 400, 400, hints);
            File file1 = new File(path, codeName + "." + imageType);
            if(!file1.exists()){
                file1.mkdirs();
            }
            MatrixToImageWriter.writeToFile(bitMatrix, imageType, file1);
            item.setQrCodeUrl("/uploadFiles/qrUrl/"+codeName+".jpg");
        } catch (WriterException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }