step1 導包

        <!-- 二維碼 -->
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.3.0</version>
        </dependency>

 step2 建立二維碼生成工具類 QRCodeUtil

package com.cmft.eams.app.common.util;


import com.google.zxing.*;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import javax.imageio.ImageIO;
import javax.print.*;
import javax.print.attribute.DocAttributeSet;
import javax.print.attribute.HashDocAttributeSet;
import javax.print.attribute.HashPrintRequestAttributeSet;
import javax.print.attribute.PrintRequestAttributeSet;
import javax.print.attribute.standard.Copies;
import javax.print.attribute.standard.MediaPrintableArea;
import javax.print.attribute.standard.MediaSizeName;
import javax.servlet.http.HttpServletResponse;
import java.awt.*;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Map;

/**
 * @Author: hg
 * @Date: 2018/12/17 16:19
 * @Version 1.0
 * Description: 二維碼生成工具類
 */
public final class QRCodeUtil extends LuminanceSource {

    private static final Logger logger = LoggerFactory.getLogger(QRCodeUtil.class);

    // 二維碼顏色
    private static final int BLACK = 0xFF000000;
    // 二維碼顏色
    private static final int WHITE = 0xFFFFFFFF;

    private final BufferedImage image;
    private final int left;
    private final int top;

    public QRCodeUtil(BufferedImage image) {
        this(image, 0, 0, image.getWidth(), image.getHeight());
    }

    public QRCodeUtil(BufferedImage image, int left, int top, int width, int height) {
        super(width, height);
        int sourceWidth = image.getWidth();
        int sourceHeight = image.getHeight();
        if (left + width > sourceWidth || top + height > sourceHeight) {
            throw new IllegalArgumentException("Crop rectangle does not fit within image data.");
        }
        for (int y = top; y < top + height; y++) {
            for (int x = left; x < left + width; x++) {
                if ((image.getRGB(x, y) & 0xFF000000) == 0) {
                    image.setRGB(x, y, 0xFFFFFFFF); // = white
                }
            }
        }
        this.image = new BufferedImage(sourceWidth, sourceHeight, 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("Requested row is outside the image: " + y);
        }
        int width = getWidth();
        if (row == null || row.length < width) {
            row = new byte[width];
        }
        image.getRaster().getDataElements(left, top + y, width, 1, row);
        return row;
    }

    @Override
    public byte[] getMatrix() {
        int width = getWidth();
        int height = getHeight();
        int area = width * height;
        byte[] matrix = new byte[area];
        image.getRaster().getDataElements(left, top, width, height, matrix);
        return matrix;
    }

    @Override
    public boolean isCropSupported() {
        return true;
    }

    @Override
    public LuminanceSource crop(int left, int top, int width, int height) {
        return new QRCodeUtil(image, this.left + left, this.top + top, width, height);
    }

    @Override
    public boolean isRotateSupported() {
        return true;
    }

    @Override
    public LuminanceSource rotateCounterClockwise() {
        int sourceWidth = image.getWidth();
        int sourceHeight = image.getHeight();
        AffineTransform transform = new AffineTransform(0.0, -1.0, 1.0, 0.0, 0.0, sourceWidth);
        BufferedImage rotatedImage = new BufferedImage(sourceHeight, sourceWidth, BufferedImage.TYPE_BYTE_GRAY);
        Graphics2D g = rotatedImage.createGraphics();
        g.drawImage(image, transform, null);
        g.dispose();
        int width = getWidth();
        return new QRCodeUtil(rotatedImage, top, sourceWidth - (left + width), getHeight(), width);
    }

    /**
     * @param matrix
     * @return
     */
    private static BufferedImage toBufferedImage(BitMatrix matrix) {
        int width = matrix.getWidth();
        int height = matrix.getHeight();
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        for (int x = 0; x < width; x++) {
            for (int y = 0; y < height; y++) {
                image.setRGB(x, y, matrix.get(x, y) ? BLACK : WHITE);
            }
        }
        return image;
    }

    /**
     * 生成二維碼圖片
     *
     * @param matrix
     * @param format
     * @param file
     * @throws IOException
     */
    public static void writeToFile(BitMatrix matrix, String format, File file) throws IOException {
        BufferedImage image = toBufferedImage(matrix);
        if (!ImageIO.write(image, format, file)) {
            throw new IOException("Could not write an image of format " + format + " to " + file);
        }
    }

    /**
     * 生成二維碼圖片流
     *
     * @param matrix
     * @param format
     * @param stream
     * @throws IOException
     */
    public static void writeToStream(BitMatrix matrix, String format, OutputStream stream) throws IOException {
        BufferedImage image = toBufferedImage(matrix);

        if (!ImageIO.write(image, format, stream)) {
            throw new IOException("Could not write an image of format " + format);
        }
    }

    /**
     * 根據內容，生成指定寬高、指定格式的二維碼圖片
     *
     * @param text   內容
     * @param width  寬
     * @param height 高
     * @param format 圖片格式
     * @return 生成的二維碼圖片路徑
     * @throws Exception
     */
    private static String generateQRCode(String text, int width, int height, String format, String pathName)
            throws Exception {
        Hashtable<EncodeHintType, Object> hints = new Hashtable<>();
        hints.put(EncodeHintType.CHARACTER_SET, "utf-8");// 指定編碼格式
        hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);// 指定糾錯等級
        hints.put(EncodeHintType.MARGIN, 1); // 白邊大小，取值範圍0~4
        BitMatrix bitMatrix = new MultiFormatWriter().encode(text, BarcodeFormat.QR_CODE, width, height, hints);
        File outputFile = new File(pathName);
        writeToFile(bitMatrix, format, outputFile);
        return pathName;
    }

    /**
     * 輸出二維碼圖片流
     *
     * @param text 二維碼內容
     * @param width 二維碼寬
     * @param height 二維碼高
     * @param format 圖片格式eg: png, jpg, gif
     * @param response HttpServletResponse
     * @throws Exception
     */
    public static void generateQRCode(String text, int width, int height, String format, HttpServletResponse response)
            throws Exception {
        Hashtable<EncodeHintType, Object> hints = new Hashtable<>();
        hints.put(EncodeHintType.CHARACTER_SET, "utf-8");// 指定編碼格式
        hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);// 指定糾錯等級
        hints.put(EncodeHintType.MARGIN, 1); // 白邊大小，取值範圍0~4
        BitMatrix bitMatrix = new MultiFormatWriter().encode(text, BarcodeFormat.QR_CODE, width, height, hints);
        writeToStream(bitMatrix, format, response.getOutputStream());
    }

    /**
     * 解析指定路徑下的二維碼圖片
     *
     * @param filePath 二維碼圖片路徑
     * @return
     */
    public static String parseQRCode(String filePath) {
        String content = "";
        try {
            File file = new File(filePath);
            BufferedImage image = ImageIO.read(file);
            LuminanceSource source = new QRCodeUtil(image);
            Binarizer binarizer = new HybridBinarizer(source);
            BinaryBitmap binaryBitmap = new BinaryBitmap(binarizer);
            Map<DecodeHintType, Object> hints = new HashMap<>();
            hints.put(DecodeHintType.CHARACTER_SET, "UTF-8");
            MultiFormatReader formatReader = new MultiFormatReader();
            Result result = formatReader.decode(binaryBitmap, hints);

            logger.info("result 為：" + result.toString());
            logger.info("resultFormat 為：" + result.getBarcodeFormat());
            logger.info("resultText 為：" + result.getText());
            // 設定返回值
            content = result.getText();
        } catch (Exception e) {
            logger.error(e.getMessage());
        }
        return content;
    }


    /**
     * 列印二維碼
     * @param fileName
     * @param count
     */
    public static void drawImage(String fileName, int count) {
        try {
            DocFlavor dof = null;

            if (fileName.endsWith(".gif")) {
                dof = DocFlavor.INPUT_STREAM.GIF;
            } else if (fileName.endsWith(".jpg")) {
                dof = DocFlavor.INPUT_STREAM.JPEG;
            } else if (fileName.endsWith(".png")) {
                dof = DocFlavor.INPUT_STREAM.PNG;
            }
            // 獲取預設印表機
            PrintService ps = PrintServiceLookup.lookupDefaultPrintService();

            PrintRequestAttributeSet pras = new HashPrintRequestAttributeSet();
//			pras.add(OrientationRequested.PORTRAIT);
//			pras.add(PrintQuality.HIGH);
            pras.add(new Copies(count));
            pras.add(MediaSizeName.ISO_A10); // 設定列印的紙張

            DocAttributeSet das = new HashDocAttributeSet();
            das.add(new MediaPrintableArea(0, 0, 1, 1, MediaPrintableArea.INCH));
            FileInputStream fin = new FileInputStream(fileName);

            Doc doc = new SimpleDoc(fin, dof, das);
            DocPrintJob job = ps.createPrintJob();

            job.print(doc, pras);
            fin.close();
        } catch (IOException ie) {
            ie.printStackTrace();
        } catch (PrintException pe) {
            pe.printStackTrace();
        }
    }


    public static void main(String[] args) {
        String text = "hello world!"; // 隨機生成驗證碼
        System.out.println("隨機碼： " + text);
        int width = 100; // 二維碼圖片的寬
        int height = 100; // 二維碼圖片的高
        String format = "png"; // 二維碼圖片的格式


        try {
            // 生成二維碼圖片，並返回圖片路徑
                String pathName = generateQRCode(text, width, height, format, "D:/new.png");
            System.out.println("生成二維碼的圖片路徑： " + pathName);

            String content = parseQRCode(pathName);
            System.out.println("解析出二維碼的圖片的內容為： " + content);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}
 

web 端顯示二維碼

以檔案形式輸出二維碼

此方法在工具類QRCodeUtil.class main方法中