Java 如何实现二维码？

Love The Way You Lie 2021-09-01 09:35 338阅读 0赞

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作者：红颜祸水nvn

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：

<?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>4.0.0</modelVersion>
 
     <groupId>org.javaboy</groupId>
     <artifactId>QRCode</artifactId>
     <version>1.0-SNAPSHOT</version>
 
 
     <dependencies>
         
         <dependency>
             <groupId>com.google.zxing</groupId>
             <artifactId>core</artifactId>
             <version>3.3.0</version>
         </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。![format_png][]

## 工具类1 (BufferedImageLuminanceSource) ##

不废话，直接上代码

/**
  * @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。

/**
  * @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。

/**
  * @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 ##

![format_png 1][]

## 源码奉上 ##

码云：https://gitee.com/jian\_bo\_bai/QRCode

--------------------

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