A simple example of Java using Zxing to generate QR code

Zxing is a barcode (one-dimensional code, two-dimensional code) parsing tool provided by Google. It provides methods for generating and parsing QR codes. Now I will briefly introduce how to use Zxing to generate and parse QR codes using Java.

1. QR code generation

1.1 Add the Zxing-core.jar package to the classpath.

1.2 The generation of QR code requires the help of the MatrixToImageWriter class, which is provided by Google. You can copy this class into the source code. Here I paste the source code of this class, which can be used directly.

import com.google.zxing.common.BitMatrix;
  
 import javax.imageio.ImageIO;
 import java.io.File;
 import java.io.OutputStream;
 import java.io.IOException;
 import java.awt.image.BufferedImage;
  
  
 public final 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);
   }
  }
  
   
  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);
   }
  }
  
 }

1.3 Write the implementation code to generate the QR code

try {
        
   String content = "120605181003;http://www.cnblogs.com/jtmjx";
   String path = "C:/Users/Administrator/Desktop/testImage";
    
   MultiFormatWriter multiFormatWriter = new MultiFormatWriter();
    
   Map hints = new HashMap();
   hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
   BitMatrix bitMatrix = multiFormatWriter.encode(content, BarcodeFormat.QR_CODE, 400, 400,hints);
   File file1 = new File(path,"餐巾纸.jpg");
   MatrixToImageWriter.writeToFile(bitMatrix, "jpg", file1);
    
 } catch (Exception e) {
   e.printStackTrace();
 }

Now you can generate a QR code image after running it. Isn’t it very simple? Next, let’s see how to parse the QR code

2. Parsing the QR code

2.1 Add the Zxing-core.jar package to the classpath.

2.2 As with generation, we need an auxiliary class (BufferedImageLuminanceSource), which is also provided by Google. Here I will also post the source code of this class. You can copy and use it directly, saving you the trouble of searching.

BufferedImageLuminanceSource 
 import com.google.zxing.LuminanceSource;
  
 import java.awt.Graphics2D;
 import java.awt.geom.AffineTransform;
 import java.awt.image.BufferedImage;
  
 public final class BufferedImageLuminanceSource extends LuminanceSource {
  
  private final BufferedImage image;
  private final int left;
  private final int top;
  
  public BufferedImageLuminanceSource(BufferedImage image) {
   this(image, 0, 0, image.getWidth(), image.getHeight());
  }
  
  public BufferedImageLuminanceSource(BufferedImage image, int left, int top, int width, int height) {
   super(width, height);
  
   int sourceWidth = image.getWidth();
   int sourceHeight = image.getHeight();
   if (left + width > sourceWidth || top + height > sourceHeight) {
    throw new IllegalArgumentException("Crop rectangle does not fit within image data.");
   }
  
   for (int y = top; y < top + height; y++) {
    for (int x = left; x < left + width; x++) {
     if ((image.getRGB(x, y) & 0xFF000000) == 0) {
      image.setRGB(x, y, 0xFFFFFFFF); // = white
     }
    }
   }
  
   this.image = new BufferedImage(sourceWidth, sourceHeight, BufferedImage.TYPE_BYTE_GRAY);
   this.image.getGraphics().drawImage(image, 0, 0, null);
   this.left = left;
   this.top = top;
  }
  
  @Override
  public byte[] getRow(int y, byte[] row) {
   if (y < 0 || y >= getHeight()) {
    throw new IllegalArgumentException("Requested row is outside the image: " + y);
   }
   int width = getWidth();
   if (row == null || row.length < width) {
    row = new byte[width];
   }
   image.getRaster().getDataElements(left, top + y, width, 1, row);
   return row;
  }
  
  @Override
  public byte[] getMatrix() {
   int width = getWidth();
   int height = getHeight();
   int area = width * height;
   byte[] matrix = new byte[area];
   image.getRaster().getDataElements(left, top, width, height, matrix);
   return matrix;
  }
  
  @Override
  public boolean isCropSupported() {
   return true;
  }
  
  @Override
  public LuminanceSource crop(int left, int top, int width, int height) {
   return new BufferedImageLuminanceSource(image, this.left + left, this.top + top, width, height);
  }
  
  @Override
  public boolean isRotateSupported() {
   return true;
  }
  
  @Override
  public LuminanceSource rotateCounterClockwise() {
  
    int sourceWidth = image.getWidth();
   int sourceHeight = image.getHeight();
  
   AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);
  
   BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY);
  
   Graphics2D g = rotatedImage.createGraphics();
   g.drawImage(image, transform, null);
   g.dispose();
  
   int width = getWidth();
   return new BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width);
  }
  
 }

2.3 Write the implementation code for parsing the QR code

try {
             MultiFormatReader formatReader = new MultiFormatReader();
       String filePath = "C:/Users/Administrator/Desktop/testImage/test.jpg";
       File file = new File(filePath);
       BufferedImage image = ImageIO.read(file);;
       LuminanceSource source = new BufferedImageLuminanceSource(image);
       Binarizer binarizer = new HybridBinarizer(source);
       BinaryBitmap binaryBitmap = new BinaryBitmap(binarizer);
       Map hints = new HashMap();
       hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
       Result result = formatReader.decode(binaryBitmap,hints);
        
             System.out.println("result = "+ result.toString());
       System.out.println("resultFormat = "+ result.getBarcodeFormat());
       System.out.println("resultText = "+ result.getText());
              
     } catch (Exception e) {
       e.printStackTrace();
     }

Now after running it, you can see that the console prints out the content of the QR code.

So far, the demonstration of using Zxing to generate and parse QR codes has been completed. It is mainly used as a memo for myself and for the convenience of those in need.

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