使用zxing生成二維碼去除白邊

生成二維碼的時候，我們通常使用google.zxing包，使用google提供的工具類生成二維碼的時候通常會帶有白色邊框，有的人覺得白色的邊框很難看，那麼怎麼去除白色的邊框呢？
我們先把zxing的源碼下載下來。然後看下這個白邊是如果產生的。

首先是創建比特矩陣(位矩陣)的QR碼編碼的字符串的代碼：

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

encode方法源碼如下：

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);
  }

在方法的最後兩行我們看到調用renderResult方法，源碼如下

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();
    //以下兩行源碼是原始代碼中控制邊距的參數
    //int qrWidth = inputWidth + (quietZone << 1);
    //int qrHeight = inputHeight + (quietZone << 1);
   //以下兩行源碼是修改後的控制邊距的參數
    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;
  }

修改代碼位置如下，具體想要使用多大的間距可以自行調整qrWidth 以及qrHeight ：

測試類：

/**
 * 二維碼生成和讀的工具類
 */
public class QRCodeUtil {

    /**
     * 生成包含字符串信息的二維碼圖片
     *
     * @param outputStream 文件輸出流路徑
     * @param content      二維碼攜帶信息
     * @param qrCodeSize   二維碼圖片大小
     * @param imageFormat  二維碼的格式
     * @throws WriterException
     * @throws IOException
     */
    public static boolean createQrCode(OutputStream outputStream, String content, int qrCodeSize, String imageFormat) throws WriterException, IOException {
        //設置二維碼糾錯級別ＭＡＰ
        Hashtable<EncodeHintType, ErrorCorrectionLevel> hintMap = new Hashtable<EncodeHintType, ErrorCorrectionLevel>();
        hintMap.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);  // 矯錯級別
        QRCodeWriterUtil qrCodeWriterUtil = new QRCodeWriterUtil();
        //創建比特矩陣(位矩陣)的QR碼編碼的字符串
        BitMatrix byteMatrix = qrCodeWriterUtil.encode(content, BarcodeFormat.QR_CODE, qrCodeSize, qrCodeSize, hintMap);
        // 使BufferedImage勾畫QRCode  (matrixWidth 是行二維碼像素點)
        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);
        // 使用比特矩陣畫並保存圖像
        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);
    }

    /**
     * 讀二維碼並輸出攜帶的信息
     */
    public static void readQrCode(InputStream inputStream) throws IOException {
        //從輸入流中獲取字符串信息
        BufferedImage image = ImageIO.read(inputStream);
        //將圖像轉換爲二進制位圖源
        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());
    }

    /**
     * 測試代碼
     *
     * @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)));
    }

}

測試結果：