基于 zxing 的二维码生成、解析

　　在很多的场景下我们需要用到二维码，这里就通过google的zxing来对二维码进行实现。

二维码生成：

1.导入依赖：

<dependency>
　　<groupId>com.google.zxing</groupId>
　　<artifactId>core</artifactId>
　　<version>2.2</version>
</dependency>
<dependency>
　　<groupId>com.google.zxing</groupId>
　　<artifactId>javase</artifactId>
　　<version>2.2</version>
</dependency>

2.编写二维码工具类，用于讲生成的二维码图片通过流的形式写到浏览器，同时支持在二维码中间添加定制图片：

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 javax.servlet.http.HttpServletResponse; import java.awt.*; import java.awt.geom.RoundRectangle2D; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import java.util.Hashtable; import static org.apache.catalina.manager.Constants.CHARSET; public class RecodeUtil { private static final int WIDTH = 30; private static final int HEIGHT = 30; public static void creatRrCode(String contents, int width, int height, HttpServletResponse response) throws Exception { Hashtable hints = new Hashtable(); hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.H); //容错级别最高
        hints.put(EncodeHintType.CHARACTER_SET, "utf-8"); //设置字符编码
        hints.put(EncodeHintType.MARGIN, 1); //二维码空白区域,最小为0也有白边,只是很小,最小是6像素左右
        try { BitMatrix bitMatrix = new MultiFormatWriter().encode(contents, BarcodeFormat.QR_CODE, width, height, hints); // 1、读取文件转换为字节数组
            BufferedImage image = toBufferedImage(bitMatrix); //转换成png格式的IO流
            ImageIO.write(image, "png", response.getOutputStream()); } catch (WriterException e) { e.printStackTrace(); } catch (IOException e) { e.printStackTrace(); } } /** * image流数据处理 */
    public static BufferedImage toBufferedImage(BitMatrix matrix) throws Exception { 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++) {//0xFF000000 0xFFFFFFFF //https://blog.csdn.net/cgwcgw_/article/details/21155229 颜色查询
                image.setRGB(x, y, matrix.get(x, y) ? 0xFF000000 : 0xFFFFFFFF); } } insertImage(image,"D:/head.jpg",true,width,height);//调用insertImage函数插入图片
        return image; } /** * 插入内嵌图片 * @param source * @param imgPath 要插入图片路径 * @param needCompress 要插入图片的像素是否大于60 * @throws Exception */
    private static void insertImage(BufferedImage source, String imgPath, boolean needCompress,int qrWidth,int qrHeight) throws Exception { File file = new File(imgPath); if(!file.exists()){ System.err.print(""+imgPath+"路径不存在！"); return; } Image src = ImageIO.read(new File(imgPath)); int width = src.getWidth(null);//获得原宽度
        int height = src.getHeight(null);//获得源高度
        if(needCompress){//比较要插入的图片的宽度是否大于设定的WIDTH=30像素宽
            if(width>WIDTH){ width = WIDTH; } if(height>HEIGHT){//比较要插入的图片的高度是否大于设定的HEIGTH=30像素宽
                height = HEIGHT; } Image image = src.getScaledInstance(width, height, //把image对象的getScaledInstance方法把图片缩小heightXwidth像素大小
 Image.SCALE_SMOOTH); BufferedImage tag = new BufferedImage(width,height,///创建一个透明色的BufferedImage对象
 BufferedImage.TYPE_INT_RGB); Graphics g = tag.getGraphics();//获得画笔
            g.drawImage(image, 0, 0, null);//绘制指定图像中当前可用的image图像，图像的左上角位于该图形上下文坐标（0，0）的 (x, y)
 } //开始画内嵌图片
        Graphics2D graph = source.createGraphics(); //计算绘画坐标
        int x = (qrWidth-width)/2; int y = (qrHeight-height)/2; graph.drawImage(src, x, y, width, height, null);//内嵌坐标为（x,y)的地方
        Shape shape = new RoundRectangle2D.Float(x,y,width,width,6,6); graph.setStroke(new BasicStroke(3f)); graph.draw(shape); graph.dispose(); } 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; } }

3.提供请求控制器：

@RestController public class QRCodeController { @GetMapping("/qrcode") public void qrcode(HttpServletRequest request, HttpServletResponse response) throws Exception { String content = "你是猪"; long l = LocalDateTime.now().toInstant(ZoneOffset.of("+8")).toEpochMilli(); content += String.valueOf(l); if (StringUtils.isBlank(content)) { System.out.println("404"); return; } //调用工具类，生成二维码
        RecodeUtil.creatRrCode(content, 180, 180, response);   //180为图片高度和宽度
 } @PostMapping("/qrcode/parse") public void read(MultipartFile file) throws Exception { File toFile = null; InputStream ins = null; ins = file.getInputStream(); toFile = new File(file.getOriginalFilename()); inputStreamToFile(ins, toFile); ins.close(); RecodeUtil.decode(toFile); } //获取流文件
    private static void inputStreamToFile(InputStream ins, File file) { try { OutputStream os = new FileOutputStream(file); int bytesRead = 0; byte[] buffer = new byte[8192]; while ((bytesRead = ins.read(buffer, 0, 8192)) != -1) { os.write(buffer, 0, bytesRead); } os.close(); ins.close(); } catch (Exception e) { e.printStackTrace(); } } }

4.通过以上的代码就完成了后端代码的编写，接下去看一下前端代码。我前端代码基于  Vue 。：

// ......省略代码 <button v-on:click="qrcode">二维码</button><br/>
<img :src = "qrcodeImage" >
<img src = "http://localhost:8889/qrcode" > export default { name: 'HelloWorld', data () { return { qrcodeImage: '' } }, methods: { qrcode: function () { this.qrcodeImage = null this.$axios({ method: 'get', url: '/api/qrcode', responseType: 'arraybuffer' }).then(function (res) { return 'data:image/png;base64,' + btoa( new Uint8Array(res.data) .reduce((data, byte) => data + String.fromCharCode(byte), '') ) }).then(data => { this.qrcodeImage = data }).catch(function (err) { alert(err) }) } }

5.启动项目，不点击二维码按钮的时候只有一个固定不变的二维码。当点击二维码按钮可以看到一下效果：

　　这样子就可以实现我们的二维码。

二维码解析：

　　二维码解析可以通过调用上述 /qrcode/parse 接口，这里采用 postman作为演示，我们先将上面得到的二维码截图保存：

　　然后就可以得到二维码的内容了。解析的代码上面也已经给出。