java实现生成二维码

时间 2021-05-21

标签 javascript css html java jquery web bootstrap 数组 app maven 栏目 Java 繁體版

原文原文链接

本篇文章将介绍java中如何生成二维码，二维码的展现主要包括两各方面：
1.直接生成图片（直接生成图片不须要web程序，maven工程便可）
2.将二维码转为字节数组，而后在web页面显示。web项目的目录结构之前面的一篇文章中的目录结构为基础（传送门）。javascript

生成二维码的功能主要是依赖Google的Zxing包。

1.添加Zxing的依赖（maven工程为例）css

<dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>javase</artifactId>
            <version>3.3.0</version>
        </dependency>

2.保存信息为二维码图片html

名为generateQRCodeImage方法，将字符串封装成二维码、设置二维码的宽度和高度、声明二维码保存的路径与图片名称。java

package org.thinkingingis.utils;
 
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;
 
import com.google.zxing.BarcodeFormat;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
 
public class QRCodeGenerator {
    
    private static final String QR_CODE_IMAGE_PATH = "/Users/gisboy/Desktop/MyQRCode.png";
    
    private static void generateQRCodeImage(String text, int width, int height, String filePath) throws WriterException, IOException {
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        
        BitMatrix bitMatrix = qrCodeWriter.encode(text, BarcodeFormat.QR_CODE, width, height);
        
        Path path = FileSystems.getDefault().getPath(filePath);
        
        MatrixToImageWriter.writeToPath(bitMatrix, "PNG", path);
        
    }
    
    public static void main(String[] args) {
        try {
            generateQRCodeImage("This is my first QR Code", 350, 350, QR_CODE_IMAGE_PATH);
        } catch (WriterException e) {
            System.out.println("Could not generate QR Code, WriterException :: " + e.getMessage());
        } catch (IOException e) {
            System.out.println("Could not generate QR Code, IOException :: " + e.getMessage());
        }
        
    }
    
 
}

上面的代码将会生成一个内容为“This is my first QR Code”二维码，并保存在桌面，以下图：jquery

上面的方法是将二维码保存为图片，若是你不想将二维码保存为图片，也能够将其保存为字节数组，能够用zxing 库提供的MatrixToImageWriter.writeToStream()方法：web

public static byte[] getQRCodeImage(String text, int width, int height) throws WriterException, IOException {
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        BitMatrix bitMatrix = qrCodeWriter.encode(text, BarcodeFormat.QR_CODE, width, height);
        
        ByteArrayOutputStream pngOutputStream = new ByteArrayOutputStream();
        MatrixToImageWriter.writeToStream(bitMatrix, "PNG", pngOutputStream);
        byte[] pngData = pngOutputStream.toByteArray(); 
        return pngData;
    }

这个方法能够将字节数组在web页面展现为图片形式。结合Spring Boot + Thymeleaf搭建的web工程，若是想在页面显示该二维码信息的话，须要在html页面和controller中完成以下代码：bootstrap

qrcode.html数组

<!DOCTYPE HTML>
<html xmlns:th="http://www.thymeleaf.org">
<head>
    <link rel="stylesheet" type="text/css" href="webjars/bootstrap/3.3.7/css/bootstrap.min.css"/>
    <script type="text/javascript" src="webjars/jquery/2.2.4/jquery.min.js"></script>
</head>
<body>
<div th:replace="fragments/header :: header"></div>
<div class="container">
    <div class="starter-template">
        <h1>QrCodeImage</h1>
    </div>
</div>
<div class="container">
    <img alt="qrcode" th:src="@{'/qrimage'}" />
    <footer>
        <p>
            © <a >ThinkingInGIS</a> 2019
        </p>
    </footer>
</div>
</body>
</html>

DefaultController.javaapp

@GetMapping("qrcode")
    public String qrcode() {
        return "/qrcode";
    }
    
    @GetMapping(value="/qrimage")
    public ResponseEntity<byte[]> getQRImage() {
        
        //二维码内的信息
        String info = "This is my first QR Code";
        
        byte[] qrcode = null;
        try {
            qrcode = QRCodeGenerator.getQRCodeImage(info, 360, 360);
        } catch (WriterException e) {
            System.out.println("Could not generate QR Code, WriterException :: " + e.getMessage());
            e.printStackTrace();
        } catch (IOException e) {
            System.out.println("Could not generate QR Code, IOException :: " + e.getMessage());
        } 
 
        // Set headers
        final HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.IMAGE_PNG);
 
        return new ResponseEntity<byte[]> (qrcode, headers, HttpStatus.CREATED);
    }

请注意qrcode.html中<img>标签中 src属性的值。maven