How to Read Or Parse QR Code in Java

摘要：有个群友在群里问，二维码生成和解析用java怎么做，正好有空，我也写了下，记录一下，有需要的同学可以参考下，这里主要是使用了Google的一个开源包zxing。

一：导入zxing的依赖，如下：

<dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.2.1</version>
        </dependency>

二：ZxingUtils工具类，其中包括生成二维码，解析二维码方法：

package com.micai.springboot.util;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.EnumMap;
import java.util.Map;

import javax.imageio.ImageIO;

import com.google.zxing.*;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.QRCodeReader;
import com.google.zxing.qrcode.QRCodeWriter;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

/**
 * @Auther: zhaoxinguo
 * @Date: 2018/7/24 15:00
 * @Description: 二维码工具类
 */
public class ZxingUtils {

    /**
     * 生成二维码
     * @param fromUrl
     * @param toUrl
     */
    public static void createQrCode(String fromUrl, String toUrl) {
        String myCodeText = fromUrl;
        String filePath = toUrl;
        int size = 250;
        String fileType = "png";
        File myFile = new File(filePath);
        try {

            Map<EncodeHintType, Object> hintMap = new EnumMap<EncodeHintType, Object>(EncodeHintType.class);
            hintMap.put(EncodeHintType.CHARACTER_SET, "UTF-8");

            // Now with zxing version 3.2.1 you could change border size (white border size to just 1)
            hintMap.put(EncodeHintType.MARGIN, 1); /* default = 4 */
            hintMap.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);

            QRCodeWriter qrCodeWriter = new QRCodeWriter();
            BitMatrix byteMatrix = qrCodeWriter.encode(myCodeText, BarcodeFormat.QR_CODE, size, size, hintMap);
            int CrunchifyWidth = byteMatrix.getWidth();
            BufferedImage image = new BufferedImage(CrunchifyWidth, CrunchifyWidth, BufferedImage.TYPE_INT_RGB);
            image.createGraphics();

            Graphics2D graphics = (Graphics2D) image.getGraphics();
            graphics.setColor(Color.WHITE);
            graphics.fillRect(0, 0, CrunchifyWidth, CrunchifyWidth);
            graphics.setColor(Color.BLACK);

            for (int i = 0; i < CrunchifyWidth; i++) {
                for (int j = 0; j < CrunchifyWidth; j++) {
                    if (byteMatrix.get(i, j)) {
                        graphics.fillRect(i, j, 1, 1);
                    }
                }
            }
            ImageIO.write(image, fileType, myFile);
        } catch (WriterException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        System.out.println("\n\nYou have successfully created QR Code.");
    }

    /**
     * 解析二维码
     * @param filePath
     * @return
     */
    public static String readQRCode(String filePath) {

        File file = new File(filePath);
        BufferedImage image = null;
        BinaryBitmap bitmap = null;
        Result result = null;

        try {
            image = ImageIO.read(file);
            int[] pixels = image.getRGB(0, 0, image.getWidth(), image.getHeight(), null, 0, image.getWidth());
            RGBLuminanceSource source = new RGBLuminanceSource(image.getWidth(), image.getHeight(), pixels);
            bitmap = new BinaryBitmap(new HybridBinarizer(source));
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        if (bitmap == null)
            return null;

        QRCodeReader reader = new QRCodeReader();
        try {
            result = reader.decode(bitmap);
            return result.getText();
        } catch (NotFoundException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (ChecksumException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } catch (FormatException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        return null;
    }

    public static void main(String [] args) {
        String myCodeText = "https://blog.csdn.net/sxdtzhaoxinguo/";
        String filePath = "D://CrunchifyQR.png";
//        createQrCode(myCodeText, filePath);
        String readQRCode = readQRCode(filePath);
        System.out.println(readQRCode);
    }
}

三：运行结果：

1.生成二维码：

2.解析二维码：

这样就实现了java生成二维码和解析二维码，这里只是简单的实现，zxing里面包含了好多api，有兴趣的同学可以自己研究，这里放个zxing的api地址：https://zxing.github.io/zxing/apidocs/index.html