Java如何实现二维码？【附源码】

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：

xml version="1.0" encoding="UTF-8"?> <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

http://www.baidu.com (二维码自动识别)

源码奉上

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