在公司项目中，经常会遇到一些页面需要弹出一个二维码，然后让用户手机扫描跳转到新页面或者显示内容

本文介绍如何 通过 Java 返回一个二维码图片，当然正常这个活应该让前端做，前端也有相关的轮子

一、引入依赖

<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>

二、Java Demo

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;

import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.Path;

public class QRDemo {

    private static final String QR_CODE_IMAGE_PATH = "D:/桌面/MyQRCode.png"; // 图片生成到一个目录

    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 {
            // 如果内容是链接，扫码会直接跳转
//            generateQRCodeImage("二维码内容", 350, 350, QR_CODE_IMAGE_PATH);
            generateQRCodeImage("https://liuyanzhao.com", 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());
        }

    }
    
}

三、SpringBoot（SpringMVC）版本返回图片

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;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;

import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;

/**
 *  二维码生成
 * @author 言曌
 * @since 2022/10/9 10:36
 */
@Controller
public class QrCodeController {
    
    @GetMapping("/generateQRCode")
    public void generateQRCode(HttpServletResponse response) throws IOException, WriterException {
        String content = "https://liuyanzhao.com";
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        BitMatrix bitMatrix = qrCodeWriter.encode(content, BarcodeFormat.QR_CODE, 350, 350);
        OutputStream os = response.getOutputStream();
        MatrixToImageWriter.writeToStream(bitMatrix, "PNG", os);
        os.flush();
        os.close();
    }
}

效果图如下：