Java generates a QR code through QRCode

I. Introduction

QR Code is a kind of matrix two-dimensional code symbol developed by Denso in September 1994. It has large information capacity, high reliability, and can represent Chinese characters and images with one-dimensional bar codes and other two-dimensional bar codes. A variety of text information, strong confidentiality and anti-counterfeiting advantages.

Download the QRCode.jar package first: https://pan.baidu.com/s/1Pb9XzWKhumgwaYrE90vyWg

Two, code examples

1. Generate a QR code

//加密：文字信息 -> 二维码
public static void encoderQRCode(String content, String imgPath, String imgType, int size) throws Exception{
    //RenderedImage是一个接口，因此要找到它的实现类 BufferedImage
    //RenderedImage bufferedImage = null;
    //代表内存中的一张图片
    BufferedImage bufferedImage = generateQRCodeCommon(content, imgType, size);
    //设置图片格式，与输出的路径
    ImageIO.write(bufferedImage, "jpg", new File("H:/qrcode.jpg"));
}

//产生一个二维码的BufferedImage
private static BufferedImage generateQRCodeCommon(String content, String imgType, int size) throws Exception{
    //QRCode对象：字符串转为boolean[][]
    Qrcode qrcode = new Qrcode();
    //设置二维码的排错率
    /**
     * 纠错等级分为
     * level L : 最大 7% 的错误能够被纠正；
     * level M : 最大 15% 的错误能够被纠正；
     * level Q : 最大 25% 的错误能够被纠正；
     * level H : 最大 30% 的错误能够被纠正；
     */
    qrcode.setQrcodeErrorCorrect('M');
    qrcode.setQrcodeEncodeMode('B');//注意版本信息 N代表数字 、A代表 a-z,A-Z、B代表 其他)
    qrcode.setQrcodeVersion(size);//尺寸  1-40

    boolean[][] codeOuts = qrcode.calQrcode(content.getBytes("gbk"));

    int imgSize = 67 + 12 * (size - 1);

    BufferedImage bufferedImage = new BufferedImage(imgSize, imgSize, BufferedImage.TYPE_INT_RGB);
    //生成一个画板
    Graphics2D graphics = bufferedImage.createGraphics();
    graphics.setBackground(Color.WHITE);//将画板的背景色设置为白色
    graphics.clearRect(0, 0, imgSize, imgSize);//初始化
    graphics.setColor(Color.BLACK);//设置画板上图像的颜色

    int pixoff = 2;
    for(int j = 0;j<codeOuts.length;j++){
        for(int i = 0;i<codeOuts.length;i++){
            if (codeOuts[j][i]) {
                graphics.fillRect(j * 3 + pixoff, i * 3 + pixoff, 3, 3);
            }
        }
    }
    //增加logo
    Image logo = ImageIO.read(new File("H:\\CSDN\\哪吒.jpg"));
    int maxWidth = bufferedImage.getWidth();
    int maxHeight = bufferedImage.getHeight();
    graphics.drawImage(logo, imgSize/5*2, imgSize/5*2, maxWidth/5, maxHeight/5, null);
    graphics.dispose();//释放空间
    bufferedImage.flush();//清理
    return bufferedImage;
}

Note: The most important thing to type code is the idea. Start with ImageIO.write(bufferedImage, "jpg", new File("H:/qrcode.jpg"));, build the parameters in turn, because RenderedImage is an interface, so you have to find Its implementation class BufferedImage,

2. Analyze the QR code

//解密
public static String decoderQRCode(String imgPath) throws IOException {
    //硬盘中图片加载入内存
    BufferedImage bufferedImage = ImageIO.read(new File(imgPath));
    //解密
    QRCodeDecoder qrCodeDecoder = new QRCodeDecoder();
    QRCodeImage qrCodeImage = new QRCodeImageImpl(bufferedImage);
    byte[] decode = qrCodeDecoder.decode(qrCodeImage);
    return new String(decode, "gbk");
}

package com.guor.qrcode;

import jp.sourceforge.qrcode.data.QRCodeImage;

import java.awt.image.BufferedImage;

public class QRCodeImageImpl implements QRCodeImage {
    BufferedImage bufferedImage;//内存中的二维码
    public QRCodeImageImpl(BufferedImage bufferedImage){
        this.bufferedImage = bufferedImage;
    }

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

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

    //像素
    @Override
    public int getPixel(int x, int y) {
        return bufferedImage.getRGB(x, y);
    }
}

3. Testing

package com.guor.qrcode;

public class QrcodeTest {
    public static void main(String[] args) throws Exception {
        String content = "https://blog.csdn.net/guorui_java/article/details/112391105";//内容信息
        String path = "H:/qrcode.jpg";
        //加密：文字信息 -> 二维码
        QRCodeUtil.encoderQRCode(content, path, "png", 20);
        //解密
        String decoderQRCode = QRCodeUtil.decoderQRCode(path);
        System.out.println(decoderQRCode);
    }
}