使用Java Servlet生成动态二维码的实现步骤

<dependencies>
    <dependency>
        <groupId>com.google.zxing</groupId>
        <artifactId>core</artifactId>
        <version>3.4.0</version>
    </dependency>
    <dependency>
        <groupId>com.google.zxing</groupId>
        <artifactId>javase</artifactId>
        <version>3.4.0</version>
    </dependency>
</dependencies>

package servlet;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.MultiFormatWriter;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

@WebServlet("/qrcode")
public class QRCodeServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // 获取需要生成二维码的数据，这里可以通过请求参数或其他方式获取
        String data = "Hello, QR Code!";
        System.out.println(data + ".....");

        // 生成二维码的 BufferedImage
        BufferedImage image = generateQRCode(data, 150, 150);

        // 设置响应的内容类型为图片
        response.setContentType("image/png");

        // 将二维码写入 HttpServletResponse 的输出流
        assert image != null;
        ImageIO.write(image, "png", response.getOutputStream());
    }

    private BufferedImage generateQRCode(String data, int width, int height) {
        try {

            System.out.println("1..........");
            // 设置二维码参数
            Map<EncodeHintType, Object> hintMap = new HashMap<>();
            hintMap.put(EncodeHintType.CHARACTER_SET, "UTF-8");
            hintMap.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);

            // 创建位矩阵(BitMatrix)来表示二维码
            BitMatrix bitMatrix = new MultiFormatWriter().encode(data, BarcodeFormat.QR_CODE, width, height, hintMap);

            // 将位矩阵渲染成二维码图片
            BufferedImage bufferedImage = MatrixToImageWriter.toBufferedImage(bitMatrix);

            // 返回生成的二维码图片
            return bufferedImage;
        } catch (Exception e) {
            System.err.println("Error generating QR Code: " + e.getMessage());
            return null;
        }
    }
}

String data = request.getParameter("text");