使用zxing生成二维码去除白边

生成二维码的时候，我们通常使用google.zxing包，使用google提供的工具类生成二维码的时候通常会带有白色边框，有的人觉得白色的边框很难看，那么怎么去除白色的边框呢？
我们先把zxing的源码下载下来。然后看下这个白边是如果产生的。

首先是创建比特矩阵(位矩阵)的QR码编码的字符串的代码：

new QRCodeWriter().encode(content, BarcodeFormat.QR_CODE, qrCodeSize, qrCodeSize, hintMap);

encode方法源码如下：

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

    if (contents.isEmpty()) {
      throw new IllegalArgumentException("Found empty contents");
    }

    if (format != BarcodeFormat.QR_CODE) {
      throw new IllegalArgumentException("Can only encode QR_CODE, but got " + format);
    }

    if (width < 0 || height < 0) {
      throw new IllegalArgumentException("Requested dimensions are too small: " + width + 'x' +
          height);
    }

    ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;
    int quietZone = QUIET_ZONE_SIZE;
    if (hints != null) {
      ErrorCorrectionLevel requestedECLevel = (ErrorCorrectionLevel) hints.get(EncodeHintType.ERROR_CORRECTION);
      if (requestedECLevel != null) {
        errorCorrectionLevel = requestedECLevel;
      }
      Integer quietZoneInt = (Integer) hints.get(EncodeHintType.MARGIN);
      if (quietZoneInt != null) {
        quietZone = quietZoneInt;
      }
    }

    QRCode code = Encoder.encode(contents, errorCorrectionLevel, hints);
    return renderResult(code, width, height, quietZone);
  }

在方法的最后两行我们看到调用renderResult方法，源码如下

private static BitMatrix renderResult(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();
    //以下两行源码是原始代码中控制边距的参数
    //int qrWidth = inputWidth + (quietZone << 1);
    //int qrHeight = inputHeight + (quietZone << 1);
   //以下两行源码是修改后的控制边距的参数
    int qrWidth = inputWidth + 2;
    int qrHeight = inputHeight + 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;
  }

修改代码位置如下，具体想要使用多大的间距可以自行调整qrWidth 以及qrHeight ：

image.png

测试类：

/**
 * 二维码生成和读的工具类
 */
public class QRCodeUtil {

    /**
     * 生成包含字符串信息的二维码图片
     *
     * @param outputStream 文件输出流路径
     * @param content      二维码携带信息
     * @param qrCodeSize   二维码图片大小
     * @param imageFormat  二维码的格式
     * @throws WriterException
     * @throws IOException
     */
    public static boolean createQrCode(OutputStream outputStream, String content, int qrCodeSize, String imageFormat) throws WriterException, IOException {
        //设置二维码纠错级别ＭＡＰ
        Hashtable<EncodeHintType, ErrorCorrectionLevel> hintMap = new Hashtable<EncodeHintType, ErrorCorrectionLevel>();
        hintMap.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);  // 矫错级别
        QRCodeWriterUtil qrCodeWriterUtil = new QRCodeWriterUtil();
        //创建比特矩阵(位矩阵)的QR码编码的字符串
        BitMatrix byteMatrix = qrCodeWriterUtil.encode(content, BarcodeFormat.QR_CODE, qrCodeSize, qrCodeSize, hintMap);
        // 使BufferedImage勾画QRCode  (matrixWidth 是行二维码像素点)
        int matrixWidth = byteMatrix.getWidth();
        BufferedImage image = new BufferedImage(matrixWidth - 20, matrixWidth - 20, BufferedImage.TYPE_INT_RGB);
        image.createGraphics();
        Graphics2D graphics = (Graphics2D) image.getGraphics();
        graphics.setColor(Color.WHITE);
        graphics.fillRect(0, 0, matrixWidth, matrixWidth);
        // 使用比特矩阵画并保存图像
        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 - 10, j - 10, 1, 1);
                }
            }
        }

        return ImageIO.write(image, imageFormat, outputStream);
    }

    /**
     * 读二维码并输出携带的信息
     */
    public static void readQrCode(InputStream inputStream) throws IOException {
        //从输入流中获取字符串信息
        BufferedImage image = ImageIO.read(inputStream);
        //将图像转换为二进制位图源
        LuminanceSource source = new BufferedImageLuminanceSource(image);
        BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
        QRCodeReader reader = new QRCodeReader();
        Result result = null;
        try {
            result = reader.decode(bitmap);
        } catch (ReaderException e) {
            e.printStackTrace();
        }
        System.out.println(result.getText());
    }

    /**
     * 测试代码
     *
     * @throws Exception
     */
    public static void main(String[] args) throws Exception {
        String fileName = "F:\\tmp" + StringUtils.generateUUID() + ".jpg";
        File workFile = new File(fileName);
        createQrCode(new FileOutputStream(workFile), "https://www.baidu.com", 500, "JPEG");

        readQrCode(new FileInputStream(ResourceUtils.getFile(fileName)));
    }

}

测试结果：