QRcode - swetake.com 提供了一个基于 Java 的 QR Code 编码类库，可在 Java 项目中使用该类库生成和解析二维码。下载页面是日文的，现将下载地址放在这里。

生成 QR Code

通过 Qrcode 类定义的方法实现。

public class QrcodeGen {

    public static void main(String[] args) {

        int width= 67 + 12 * ( 7 -1 );
        int height = 67 + 12 * ( 7 -1 );
        BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
        Graphics2D gs = image.createGraphics();
        gs.setBackground(Color.white);
        gs.setColor(Color.BLACK);
        gs.clearRect(0, 0, width, height);

        Qrcode x = new Qrcode();
        x.setQrcodeErrorCorrect('M');
        x.setQrcodeEncodeMode('B');//N代表数字，A代表a-z,B代表其他字符
        x.setQrcodeVersion(7);

        String qrData = "https://guo-long.github.io/";

        int pixoff = 2;//偏移量

        byte[] d = qrData.getBytes();
        if(d.length>0 && d.length<120){
            boolean[][] s = x.calQrcode(d);

            for(int i = 0; i < s.length; i++){
                for(int j = 0; j < s.length; j++){
                    if(s[j][i]){
                        gs.fillRect(j*3 + pixoff, i*3+pixoff, 3, 3);
                    }
                }
            }
        }

        gs.dispose();
        image.flush();
        try {
            ImageIO.write(image, "png", new File("barcode/qrcode.png"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

解析 QR Code

public class QrcodeReader {

    public static void main(String[] args) {
        File file = new File("barcode/qrcode.png");
        BufferedImage image = null;
        try {
             image = ImageIO.read(file);
             QRCodeDecoder decoder = new QRCodeDecoder();
             String result = new String(decoder.decode(new QRCodeImageImpl(image)),"utf-8");
             System.out.println(result);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

public class QRCodeImageImpl implements QRCodeImage{

    private BufferedImage image;

    public QRCodeImageImpl(BufferedImage image){
        this.image = image;
    }

    @Override
    public int getHeight() {
        return image.getHeight();
    }

    @Override
    public int getPixel(int arg0, int arg1) {
        return image.getRGB(arg0, arg1);
    }

    @Override
    public int getWidth() {
        return image.getWidth();
    }

}