Java基于zxing生成二维码矩阵过程解析

<dependency>
      <groupId>com.google.zxing</groupId>
      <artifactId>core</artifactId>
      <version>3.2.0</version>
    </dependency>

* 生成二维码图片
   * @param dir    存放的目录
   * @param fileName 文件名要以.jpg结尾
   * @param content 这个内容可以是文字或链接
   */
  public static void generateQRCode(String dir, String fileName, String content) {
    //生成二维码的宽高
    int size = 400;
    Map<EncodeHintType, Object> hints = new Hashtable<EncodeHintType, Object>();
    // 指定纠错等级
    hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);
    // 指定编码格式
    hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
    // 指定二维码的边距，设置后无效，，设置纠错等级ErrorCorrectionLevel.H为高等级时，无效    //hints.put(EncodeHintType.MARGIN, 1);
    try {
      //encode(String contents, BarcodeFormat format, int width, int height, Map<EncodeHintType, ?> hints)
      BitMatrix bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, size, size, hints);

      //bitMatrix = updateBit(bitMatrix, 20);
      File file1 = new File(dir);
      if (!file1.exists()) {
        file1.mkdirs();
      }

      //将生成的矩阵像素写入到指定文件中，这里是以jpg结尾
      MatrixToImageWriter.writeToStream(bitMatrix, "jpg", new FileOutputStream(dir + "/" + fileName));
      System.out.println("创建成功");
    } catch (UnsupportedEncodingException e) {
      e.printStackTrace();
    } catch (WriterException e) {
      e.printStackTrace();
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

/** L = ~7% correction */
 L(0x01),
 /** M = ~15% correction */
 M(0x00),
 /** Q = ~25% correction */
 Q(0x03),
 /** H = ~30% correction */
 H(0x02);

private static BitMatrix updateBit(BitMatrix matrix, int margin) {

    int tempM = margin * 2;

    //left,top,width,height 
    // 0  1  2   3  对应的数组下标
    //这里的width和height是指去除白色边框后的真实的二维码长宽，而不是图片长宽。
    int[] rec = matrix.getEnclosingRectangle(); // 获取二维码图案的属性

    int resWidth = rec[2] + tempM;//真实宽度加左右边距
    int resHeight = rec[3] + tempM;

    BitMatrix resMatrix = new BitMatrix(resWidth, resHeight); // 按照自定义边框生成新的BitMatrix

    resMatrix.clear();
    //从上->下按列进行值得复制，即一列一列的扫描到新的二维矩阵中
    for (int i = margin; i < resWidth - margin; i++) { // 循环，将二维码图案绘制到新的bitMatrix中

      for (int j = margin; j < resHeight - margin; j++) {
        //margin + rec[0]
        if (matrix.get(i - margin + rec[0], j - margin + rec[1])) {
          resMatrix.set(i, j);
        }
      }
    }
    return resMatrix;
  }

public void insertQRCode(BufferedImage zxingImage, String backgroundPath) {
    InputStream dest = null;

    try {
      dest = new FileInputStream(backgroundPath);
      BufferedImage image = ImageIO.read(dest);

      Graphics g = image.getGraphics();

      int leftMargin = image.getWidth() - zxingImage.getWidth() - 10;
      int topMargin = image.getHeight() - zxingImage.getHeight() - 10;
      g.drawImage(zxingImage, leftMargin, topMargin, zxingImage.getWidth(), zxingImage.getHeight(), null);
      ImageIO.write(image, "jpg", new FileOutputStream("D:\\QRCode\\zengmei.jpg"));
      System.out.println("创建成功");
      
    } catch (IOException e) {
      e.printStackTrace();
    }
  }

/**
   * 
   * @param onColor 二维码的颜色，即黑白二维码的黑色 :0xFF000000 蓝色 0xFF000055
   * @param offColor 二维码的背景色  如白色：0xFFFFFFFF
   */
  public static void generateOtherQRCode(int onColor, int offColor) {
    String content = "小姐姐最棒啦^_^";
    int size = 200;
    Map<EncodeHintType, Object> hints = new Hashtable<EncodeHintType, Object>();
    // 指定纠错等级
    hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.Q);
    // 指定编码格式
    hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
    try {
      BitMatrix bitMatrix = new MultiFormatWriter().encode(content, BarcodeFormat.QR_CODE, size, size, hints);
      BufferedImage image = MatrixToImageWriter.toBufferedImage(bitMatrix,
          new MatrixToImageConfig(onColor, offColor));

      ImageIO.write(image, "png", new FileOutputStream("D:/QRCode/beautiful.png"));
      System.out.println("操作成功");
      
    } catch (IOException e) {
      e.printStackTrace();
    } catch (WriterException e) {
      e.printStackTrace();
    }
  }

public static BufferedImage toBufferedImage(BitMatrix matrix, MatrixToImageConfig config) {
  int width = matrix.getWidth();
  int height = matrix.getHeight();
  BufferedImage image = new BufferedImage(width, height, config.getBufferedImageColorModel());
  int onColor = config.getPixelOnColor();
  int offColor = config.getPixelOffColor();
  for (int x = 0; x < width; x++) {
   for (int y = 0; y < height; y++) {
    image.setRGB(x, y, matrix.get(x, y) ? onColor : offColor);
   }
  }
  return image;
 }

//imageType ， zxing支持的图像类型有三种，黑白颜色的默认为BufferedImage.TYPE_BYTE_BINARY = 12，图像不带透明度alpha  最多是4bit的的图像TYPE_INT_RGB 这个是不带alpha的8bit图像TYPE_INT_ARGB 这个带alpha的8bit图像
java.awt.image.BufferedImage.BufferedImage(int width, int height, int imageType)