生成二维码接口

依赖

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

@GetMapping("/qr")
public void testQR(HttpServletResponse response, String msg, Integer size) throws IOException, WriterException {
    response.setContentType("image/png");
    response.setDateHeader("Expires", 0);
    Map<EncodeHintType, Object> hints = new HashMap<>();
    hints.put(EncodeHintType.MARGIN, 0);
    BitMatrix bitMatrix = new MultiFormatWriter().encode(msg, BarcodeFormat.QR_CODE, size, size, hints);
    QrCodeUtil.writeToStream(bitMatrix,"png",response.getOutputStream());
}

public class QrCodeUtil {

    /** 使用说明 **/
    private static String createQrCode(String url, String path, String fileName) {
        try {
            Map<EncodeHintType, Object> hints = new HashMap<>();
            hints.put(EncodeHintType.MARGIN, 0);
            BitMatrix bitMatrix = new MultiFormatWriter().encode(url, BarcodeFormat.QR_CODE, 400, 400, hints);
            File file = new File(path, fileName);
            if (file.exists() || ((file.getParentFile().exists() || file.getParentFile().mkdirs()) && file.createNewFile())) {
                writeToFile(bitMatrix, "jpg", file);
                System.out.println("搞定：" + file);
            }

        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

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

    private static final int BLACK = 0xFF000000;
    private static final int WHITE = 0xFFFFFFFF;
    private 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 BitMatrix getBitMatrix(QRCode code, int width, int height, int quietZone) {
        ByteMatrix input = code.getMatrix();
        if (input == null) {
            throw new IllegalStateException();
        }
        int inputWidth = input.getWidth();
        int inputHeight = input.getHeight();
        int qrWidth = inputWidth + (quietZone * 2);
        int qrHeight = inputHeight + (quietZone * 2);
        int outputWidth = Math.max(width, qrWidth);
        int outputHeight = Math.max(height, qrHeight);

        int multiple = Math.min(outputWidth / qrWidth, outputHeight / qrHeight);
        // Padding includes both the quiet zone and the extra white pixels to accommodate the requested
        // dimensions. For example, if input is 25x25 the QR will be 33x33 including the quiet zone.
        // If the requested size is 200x160, the multiple will be 4, for a QR of 132x132. These will
        // handle all the padding from 100x100 (the actual QR) up to 200x160.
        int leftPadding = (outputWidth - (inputWidth * multiple)) / 2;
        int topPadding = (outputHeight - (inputHeight * multiple)) / 2;

        BitMatrix output = new BitMatrix(outputWidth, outputHeight);

        for (int inputY = 0, outputY = topPadding; inputY < inputHeight; inputY++, outputY += multiple) {
            // Write the contents of this row of the barcode
            for (int inputX = 0, outputX = leftPadding; inputX < inputWidth; inputX++, outputX += multiple) {
                if (input.get(inputX, inputY) == 1) {
                    output.setRegion(outputX, outputY, multiple, multiple);
                }
            }
        }

        return output;
    }

}