Java ZXing 實現 QR Code 生成與解析完整教程（含輔助類源碼）

依賴準備

<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>core</artifactId>
    <version>3.5.1</version>
</dependency>
<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>javase</artifactId>
    <version>3.5.1</version>
</dependency>

生成 QR Code

public void generateQR(String content, String filePath) throws Exception {
    Map<EncodeHintType, Object> hints = new EnumMap<>(EncodeHintType.class);
    hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
    hints.put(EncodeHintType.MARGIN, 1); // 邊距

    BitMatrix matrix = new MultiFormatWriter()
            .encode(content, BarcodeFormat.QR_CODE, 400, 400, hints);

    MatrixToImageWriter.writeToPath(matrix, "PNG", Paths.get(filePath));
}

MatrixToImageWriter 輔助類（官方未打包，需自行複製）

public final class MatrixToImageWriter {
    private static final int BLACK = 0xFF000000;
    private static final int WHITE = 0xFFFFFFFF;

    public static BufferedImage toBufferedImage(BitMatrix matrix) {
        int w = matrix.getWidth(), h = matrix.getHeight();
        BufferedImage img = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
        for (int x = 0; x < w; x++)
            for (int y = 0; y < h; y++)
                img.setRGB(x, y, matrix.get(x, y) ? BLACK : WHITE);
        return img;
    }
    public static void writeToFile(BitMatrix matrix, String format, File file) throws IOException {
        if (!ImageIO.write(toBufferedImage(matrix), format, file))
            throw new IOException("Could not write " + format + " to " + file);
    }
    public static void writeToStream(BitMatrix matrix, String format, OutputStream stream) throws IOException {
        if (!ImageIO.write(toBufferedImage(matrix), format, stream))
            throw new IOException("Could not write " + format);
    }
    public static void writeToPath(BitMatrix matrix, String format, Path path) throws IOException {
        try (OutputStream os = Files.newOutputStream(path)) { writeToStream(matrix, format, os); }
    }
}

解析 QR Code

public String decodeQR(String imagePath) throws Exception {
    BufferedImage img = ImageIO.read(new File(imagePath));
    LuminanceSource source = new BufferedImageLuminanceSource(img);
    BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
    Map<DecodeHintType, Object> hints = new EnumMap<>(DecodeHintType.class);
    hints.put(DecodeHintType.CHARACTER_SET, "UTF-8");
    Result result = new MultiFormatReader().decode(bitmap, hints);
    return result.getText();
}

BufferedImageLuminanceSource 輔助類（官方未打包，需自行複製）

public final class BufferedImageLuminanceSource extends LuminanceSource {
    private final BufferedImage image;
    private final int left, 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);
        this.image = new BufferedImage(image.getWidth(), image.getHeight(), 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();
        int w = getWidth();
        if (row == null || row.length < w) row = new byte[w];
        image.getRaster().getDataElements(left, top + y, w, 1, row);
        return row;
    }
    @Override public byte[] getMatrix() {
        byte[] m = new byte[getWidth() * getHeight()];
        image.getRaster().getDataElements(left, top, getWidth(), getHeight(), m);
        return m;
    }
    @Override public boolean isCropSupported() { return true; }
    @Override public LuminanceSource crop(int l, int t, int w, int h) {
        return new BufferedImageLuminanceSource(image, left + l, top + t, w, h);
    }
    @Override public boolean isRotateSupported() { return true; }
    @Override public LuminanceSource rotateCounterClockwise() {
        int sw = image.getWidth(), sh = image.getHeight();
        AffineTransform at = new AffineTransform(0, -1, 1, 0, 0, sw);
        BufferedImage rot = new BufferedImage(sh, sw, BufferedImage.TYPE_BYTE_GRAY);
        Graphics2D g = rot.createGraphics();
        g.drawImage(image, at, null); g.dispose();
        return new BufferedImageLuminanceSource(rot, top, sw - (left + getWidth()), getHeight(), getWidth());
    }
}