Java如何实现二维码？【附源码】-技术圈

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来源：http://suo.im/5R6ewH

步骤1

第一步首先创建一个普通的 Maven 项目，然后要实现二维码功能，我们肯定要使用别人提供好的 Jar 包，这里我用的是 google 提供的 jar，pom.xml 文件配置如下：

<project xmlns="http://maven.apache.org/POM/4.0.0"         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">    <modelVersion>4.0.0modelVersion>
    <groupId>org.javaboygroupId>    <artifactId>QRCodeartifactId>    <version>1.0-SNAPSHOTversion>

    <dependencies>                <dependency>            <groupId>com.google.zxinggroupId>            <artifactId>coreartifactId>            <version>3.3.0version>        dependency>    dependencies>
project>

步骤2

然后使用 google 提供的工具类，在项目根目录下创建一个 util 包，将所需要的工具类放进去。

工具类1 (BufferedImageLuminanceSource)

不废话，直接上代码

package org.javaboy.util;
import java.awt.Graphics2D;import java.awt.geom.AffineTransform;import java.awt.image.BufferedImage;
import com.google.zxing.LuminanceSource;
/** * @author bai 
 * @date 2020/7/1 9:27
 */public class BufferedImageLuminanceSource extends LuminanceSource {
    private final BufferedImage image;    private final int left;    private final int top;
    public BufferedImageLuminanceSource(BufferedImage image) {        this(image, 0, 0, image.getWidth(), image.getHeight());    }
    public BufferedImageLuminanceSource(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 BufferedImageLuminanceSource(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 BufferedImageLuminanceSource(rotatedImage, top, sourceWidth - (left + width), getHeight(), width);    }
}

工具类2 (QRCodeUtil)

这里面可以修改一些参数，例如二维码的尺寸，宽高等等。

package org.javaboy.util;

import java.awt.BasicStroke;import java.awt.Graphics;import java.awt.Graphics2D;import java.awt.Image;import java.awt.Shape;import java.awt.geom.RoundRectangle2D;import java.awt.image.BufferedImage;import java.io.File;import java.io.OutputStream;import java.util.Hashtable;import javax.imageio.ImageIO;
import com.google.zxing.BarcodeFormat;import com.google.zxing.BinaryBitmap;import com.google.zxing.DecodeHintType;import com.google.zxing.EncodeHintType;import com.google.zxing.MultiFormatReader;import com.google.zxing.MultiFormatWriter;import com.google.zxing.Result;import com.google.zxing.common.BitMatrix;import com.google.zxing.common.HybridBinarizer;import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
/** * @author bai 
 * @date 2020/7/1 9:29
 */public class QRCodeUtil {    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 = 300;    // LOGO宽度    private static final int WIDTH = 60;    // LOGO高度    private static final int HEIGHT = 60;
    private static BufferedImage createImage(String content, String imgPath, boolean needCompress) throws Exception {        Hashtable hints = new Hashtable();        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 (imgPath == null || "".equals(imgPath)) {            return image;        }        // 插入图片        QRCodeUtil.insertImage(image, imgPath, needCompress);        return image;    }
    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();    }
    public static void encode(String content, String imgPath, String destPath, boolean needCompress) throws Exception {        BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress);        mkdirs(destPath);        // String file = new Random().nextInt(99999999)+".jpg";        // ImageIO.write(image, FORMAT_NAME, new File(destPath+"/"+file));        ImageIO.write(image, FORMAT_NAME, new File(destPath));    }
    public static BufferedImage encode(String content, String imgPath, boolean needCompress) throws Exception {        BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress);        return image;    }
    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();        }    }
    public static void encode(String content, String imgPath, String destPath) throws Exception {        QRCodeUtil.encode(content, imgPath, destPath, false);    }    // 被注释的方法    /*     * public static void encode(String content, String destPath, boolean     * needCompress) throws Exception { QRCodeUtil.encode(content, null, destPath,     * needCompress); }     */
    public static void encode(String content, String destPath) throws Exception {        QRCodeUtil.encode(content, null, destPath, false);    }
    public static void encode(String content, String imgPath, OutputStream output, boolean needCompress)            throws Exception {        BufferedImage image = QRCodeUtil.createImage(content, imgPath, needCompress);        ImageIO.write(image, FORMAT_NAME, output);    }
    public static void encode(String content, OutputStream output) throws Exception {        QRCodeUtil.encode(content, null, output, false);    }
    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 hints = new Hashtable();        hints.put(DecodeHintType.CHARACTER_SET, CHARSET);        result = new MultiFormatReader().decode(bitmap, hints);        String resultStr = result.getText();        return resultStr;    }
    public static String decode(String path) throws Exception {        return QRCodeUtil.decode(new File(path));    }
}

启动类

这一步就是调用方法，一般大家使用这种功能都是为了实现业务，例如常见的扫描二维码跳转链接（页面），扫描二维码出现文字等等。有些二维码中间还带有 Logo 这种图片，将需要嵌入二维码的图片路径准备好就没有问题。

package org.javaboy;
import org.javaboy.util.QRCodeUtil;
/** * @author bai 
 * @date 2020/7/1 9:31
 */public class QRCodeApplication {    public static void main(String[] args) throws Exception {        // 存放在二维码中的内容        // 二维码中的内容可以是文字，可以是链接等        String text = "http://www.baidu.com";        // 嵌入二维码的图片路径        //String imgPath = "C:\\Users\\Administrator\\Pictures\\img\\dog.jpg";        // 生成的二维码的路径及名称        String destPath = "C:\\Users\\bai\\Pictures\\img\\code" + System.currentTimeMillis() + ".jpg";        //生成二维码        QRCodeUtil.encode(text, null, destPath, true);        // 解析二维码        String str = QRCodeUtil.decode(destPath);        // 打印出解析出的内容        System.out.println(str);    }}

效果截图

源码奉上

码云：https://gitee.com/jian_bo_bai/QRCode

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