Java parses QR code through opencv (WeChat open source decoding tool)

        In the past, google.zxing was used to parse QR codes in Java, but the success rate of zxing in parsing QR codes was relatively low, and many beautified or personalized QR codes could not be parsed.

        WeChat open sourced its QR code decoding function and contributed it to the OpenCV community. Its open source wechat_qrcode project is included in the OpenCV contrib project. Starting from OpenCV version 4.5.2, it can be used directly.

Import dependent packages first

<dependency>
   <groupId>org.bytedeco</groupId>
   <artifactId>javacpp</artifactId>
   <version>1.5.7</version>
   <classifier>windows-x86_64</classifier>
</dependency>
<dependency>
    <groupId>org.bytedeco</groupId>
    <artifactId>openblas</artifactId>
    <version>0.3.19-1.5.7</version>
    <classifier>windows-x86_64</classifier>
</dependency>
<dependency>
    <groupId>org.bytedeco</groupId>
    <artifactId>opencv</artifactId>
    <version>4.5.5-1.5.7</version>
</dependency>
<dependency>
     <groupId>org.bytedeco</groupId>
     <artifactId>opencv</artifactId>
      <version>4.5.5-1.5.7</version>
      <classifier>windows-x86_64</classifier>
</dependency>

The above dependencies are for windows systems. If you want to publish to liunx systems, change windows-x86_64 to liunx-x86_64.

The following is the parsing code

package com.dyserver.bean;

import org.bytedeco.opencv.opencv_core.Mat;
import org.bytedeco.opencv.opencv_core.StringVector;
import org.bytedeco.opencv.opencv_wechat_qrcode.WeChatQRCode;

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;

import javax.imageio.ImageIO;

import static org.bytedeco.opencv.global.opencv_imgcodecs.imread;

/**
 * @author ChenYi
 */
public class WeChatDeCode {

	public static void main(String... args) {
		Mat img = imread("d:\\img" + "\\" + "1.png");
		System.out.println(deCode(img));
		
		//下载二维码到本地识别
		String url="";
		System.out.println(openPic(url));
	}

	public static String openPic(String url) {

		String savePath = "d:\\img";
		String filename = UUID.randomUUID().toString() + ".jpg";
		String re="0";
		try {
			dxz(url, savePath, filename);		
			Mat img = imread(savePath + "\\" + filename);
			re=deCode(img);
			//如果识别失败那么尝试放大缩小图片尝试识别，提高准确率
			if(re.equals("0")) {
				ys(savePath, filename);
				Mat img1 = imread(savePath + "\\1_" + filename);
				re=deCode(img1);
			}
			if(re.equals("0")) {
				fd(savePath, filename);
				Mat img2 = imread(savePath + "\\2_" + filename);
				re=deCode(img2);
			}
			return re;
			
			
			
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
			return "0";
		}
	}

	private static void ys(String savePath, String filename) throws Exception {
		try {
			// 读取原始图片
			BufferedImage image = ImageIO.read(new FileInputStream(savePath + "\\" + filename));
			System.out.println("Width: " + image.getWidth());
			System.out.println("Height: " + image.getHeight());
			// 调整图片大小
			BufferedImage newImage = ImageUtils.resizeImage(image, image.getWidth()*2, image.getHeight()*2);
			// 图像缓冲区图片保存为图片文件(文件不存在会自动创建文件保存，文件存在会覆盖原文件保存)
			ImageIO.write(newImage, "jpg", new File(savePath + "\\1_" + filename));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private static void fd(String savePath, String filename) throws Exception {
		try {
			// 读取原始图片
			BufferedImage image = ImageIO.read(new FileInputStream(savePath + "\\" + filename));
			System.out.println("Width: " + image.getWidth());
			System.out.println("Height: " + image.getHeight());
			// 调整图片大小
			BufferedImage newImage = ImageUtils.resizeImage(image, 200, 200);
			// 图像缓冲区图片保存为图片文件(文件不存在会自动创建文件保存，文件存在会覆盖原文件保存)
			ImageIO.write(newImage, "jpg", new File(savePath + "\\2_" + filename));
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private static void dxz(String urlString, String savePath, String filename) throws Exception {
		// 构造URL
		URL url = new URL(urlString);
		// 打开连接
		URLConnection con = url.openConnection();
		// 设置请求超时为20s
		con.setConnectTimeout(20 * 1000);
		// 文件路径不存在 则创建
		File sf = new File(savePath);
		if (!sf.exists()) {
			sf.mkdirs();
		}
		// jdk 1.7 新特性自动关闭
		try (InputStream in = con.getInputStream();
				OutputStream out = new FileOutputStream(sf.getPath() + "\\" + filename)) {
			// 创建缓冲区
			byte[] buff = new byte[1024];
			int n;
			// 开始读取
			while ((n = in.read(buff)) >= 0) {
				out.write(buff, 0, n);
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
	}

	private static String deCode(Mat img) {
		// 微信二维码对象，要返回二维码坐标前2个参数必传；后2个在二维码小或不清晰时必传。
		WeChatQRCode we = new WeChatQRCode();
		List<Mat> points = new ArrayList<Mat>();
		// 微信二维码引擎解码，返回的valList中存放的是解码后的数据，points中Mat存放的是二维码4个角的坐标
		StringVector stringVector = we.detectAndDecode(img);

		if (stringVector.empty()) {
			return "0";
		}

		System.out.println(stringVector.get(0).getString(StandardCharsets.UTF_8));
		return stringVector.get(0).getString(StandardCharsets.UTF_8);
	}

}