什么是ZXing？

ZXing是一个开源的，用Java实现的多种格式的1D/2D条码图像处理库。

利用ZXing这个工具库来生成二维码，具体操作如下：

引入相关资源包

<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>core</artifactId>
    <version>3.4.0</version>
</dependency>
<dependency>
    <groupId>com.google.zxing</groupId>
    <artifactId>javase</artifactId>
    <version>3.4.0</version>
</dependency>

编写工具类

package org.tianshun.common.utils;

import com.google.zxing.*;
import com.google.zxing.client.j2se.BufferedImageLuminanceSource;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.geom.RoundRectangle2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.OutputStream;
import java.util.Hashtable;
import java.util.Random;

/**
 * 生成二维码的工具类
 */
public class QRCodeUtils {

    private static final String CHARSET = "utf-8";
    private static final String FORMAT_NAME = "JPG";
    // 二维码尺寸
    private static final int QRCODE_SIZE = 400;
    // LOGO宽度
    private static final int WIDTH = 60;
    // LOGO高度
    private static final int HEIGHT = 60;

    public static BufferedImage createImage(String content, String logoPath,
                                            boolean needCompress) throws Exception {
        Hashtable<EncodeHintType, Object> hints = new Hashtable<EncodeHintType, Object>();
        hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H);
        hints.put(EncodeHintType.CHARACTER_SET, CHARSET);
        hints.put(EncodeHintType.MARGIN, 1);
        BitMatrix bitMatrix = new MultiFormatWriter().encode(content,
                BarcodeFormat.QR_CODE, QRCODE_SIZE, QRCODE_SIZE, hints);
        int width = bitMatrix.getWidth();
        int height = bitMatrix.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, bitMatrix.get(x, y) ? 0xFF000000
                        : 0xFFFFFFFF);
            }
        }
        if (logoPath == null || "".equals(logoPath)) {


            return image;
        }
        // 插入图片
        QRCodeUtils.insertImage(image, logoPath, needCompress);
        return image;
    }

    /**
     * 插入LOGO
     *
     * @param source       二维码图片
     * @param imgPath      LOGO图片地址
     * @param needCompress 是否压缩
     * @throws Exception
     */
    private static void insertImage(BufferedImage source, String imgPath,
                                    boolean needCompress) throws Exception {
        File file = new File(imgPath);
        if (!file.exists()) {
            System.err.println("" + imgPath + "   该文件不存在！");
            return;
        }
        Image src = ImageIO.read(new File(imgPath));
        int width = src.getWidth(null);
        int height = src.getHeight(null);
        if (needCompress) { // 压缩LOGO
            if (width > WIDTH) {
                width = WIDTH;
            }
            if (height > HEIGHT) {
                height = HEIGHT;
            }
            Image image = src.getScaledInstance(width, height,
                    Image.SCALE_SMOOTH);
            BufferedImage tag = new BufferedImage(width, height,
                    BufferedImage.TYPE_INT_RGB);
            Graphics g = tag.getGraphics();
            g.drawImage(image, 0, 0, null); // 绘制缩小后的图
            g.dispose();
            src = image;
        }
        // 插入LOGO
        Graphics2D graph = source.createGraphics();
        int x = (QRCODE_SIZE - width) / 2;
        int y = (QRCODE_SIZE - height) / 2;
        graph.drawImage(src, x, y, width, height, null);
        Shape shape = new RoundRectangle2D.Float(x, y, width, width, 6, 6);
        graph.setStroke(new BasicStroke(3f));
        graph.draw(shape);
        graph.dispose();
    }

    /**
     * 生成二维码(内嵌LOGO)
     *
     * @param content      内容
     * @param logoPath      LOGO地址
     * @param destPath     存放目录
     * @param needCompress 是否压缩LOGO
     * @throws Exception
     */
    public static String encode(String content, String logoPath, String destPath,
                                boolean needCompress) throws Exception {
        BufferedImage image = QRCodeUtils.createImage(content, logoPath,
                needCompress);
        mkdirs(destPath);
        String file = new Random().nextInt(99999999) + ".jpg";
        ImageIO.write(image, FORMAT_NAME, new File(destPath + "/" + file));
        return file;
    }

    /**
     * 当文件夹不存在时，mkdirs会自动创建多层目录，区别于mkdir．(mkdir如果父目录不存在则会抛出异常)
     *
     * @param destPath 存放目录
     * @date 2013-12-11 上午10:16:36
     */
    public static void mkdirs(String destPath) {
        File file = new File(destPath);
        //当文件夹不存在时，mkdirs会自动创建多层目录，区别于mkdir．(mkdir如果父目录不存在则会抛出异常)
        if (!file.exists() && !file.isDirectory()) {
            file.mkdirs();
        }
    }

    /**
     * 生成二维码(内嵌LOGO)
     *
     * @param content  内容
     * @param imgPath  LOGO地址
     * @param destPath 存储地址
     * @throws Exception
     */
    public static void encode(String content, String imgPath, String destPath)
            throws Exception {
        QRCodeUtils.encode(content, imgPath, destPath, false);
    }

    /**
     * 生成二维码
     *
     * @param content      内容
     * @param destPath     存储地址
     * @param needCompress 是否压缩LOGO
     * @throws Exception
     */
    public static void encode(String content, String destPath,
                              boolean needCompress) throws Exception {
        QRCodeUtils.encode(content, null, destPath, needCompress);
    }

    /**
     * 生成二维码
     *
     * @param content  内容
     * @param destPath 存储地址
     * @throws Exception
     */
    public static void encode(String content, String destPath) throws Exception {
        QRCodeUtils.encode(content, null, destPath, false);
    }

    /**
     * 生成二维码(内嵌LOGO)
     *
     * @param content      内容
     * @param imgPath      LOGO地址
     * @param output       输出流
     * @param needCompress 是否压缩LOGO
     * @throws Exception
     */
    public static void encode(String content, String imgPath,
                              OutputStream output, boolean needCompress) throws Exception {
        BufferedImage image = QRCodeUtils.createImage(content, imgPath,
                needCompress);
        ImageIO.write(image, FORMAT_NAME, output);
    }

    /**
     * 生成二维码
     *
     * @param content 内容
     * @param output  输出流
     * @throws Exception
     */
    public static void encode(String content, OutputStream output)
            throws Exception {
        QRCodeUtils.encode(content, null, output, false);
    }

    /**
     * 解析二维码
     *
     * @param file 二维码图片
     * @return
     * @throws Exception
     */
    public static String decode(File file) throws Exception {
        BufferedImage image;
        image = ImageIO.read(file);
        if (image == null) {
            return null;
        }
        BufferedImageLuminanceSource source = new BufferedImageLuminanceSource(
                image);
        BinaryBitmap bitmap = new BinaryBitmap(new HybridBinarizer(source));
        Result result;
        Hashtable<DecodeHintType, Object> hints = new Hashtable<DecodeHintType, Object>();
        hints.put(DecodeHintType.CHARACTER_SET, CHARSET);
        result = new MultiFormatReader().decode(bitmap, hints);
        String resultStr = result.getText();
        return resultStr;
    }

    /**
     * 解析二维码
     *
     * @param path 二维码图片地址
     * @return
     * @throws Exception
     */
    public static String decode(String path) throws Exception {
        return QRCodeUtils.decode(new File(path));
    }

    public static void main(String[] args) throws Exception {
        String text ="www.baidu.com";
        String logoPath = "C:\\Users\\admin\\Desktop\\test\\test.jpg";
        String destPath = "D:\\";
        System.out.println(QRCodeUtils.encode(text, null, destPath, true));
    }
}

执行main方法生成二维码图片并保存到本地相应位置。