Add dependencies

		<!-- ZXing Core -->
		<dependency>
			<groupId>com.google.zxing</groupId>
			<artifactId>core</artifactId>
			<version>3.5.1</version>
		</dependency>

		<!-- ZXing Java SE -->
		<dependency>
			<groupId>com.google.zxing</groupId>
			<artifactId>javase</artifactId>
			<version>3.5.1</version>
		</dependency>

A QR Generator class

package com.example.qr_generator.util;

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.ByteArrayOutputStream;
import java.io.IOException;

public class QRCodeGenerator {

    public static byte[] generateQRCodeImage(String text, int width, int height) throws WriterException, IOException {
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        BitMatrix bitMatrix = qrCodeWriter.encode(text, BarcodeFormat.QR_CODE, width, height);

        try (ByteArrayOutputStream pngOutputStream = new ByteArrayOutputStream()) {
            MatrixToImageWriter.writeToStream(bitMatrix, "PNG", pngOutputStream);
            return pngOutputStream.toByteArray();
        }
    }
}

Controller and business logic

package com.example.qr_generator.controller;

import com.example.qr_generator.util.QRCodeGenerator;
import com.google.zxing.WriterException;
import lombok.extern.slf4j.Slf4j;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.io.IOException;

@RestController
@RequestMapping("/api")
@Slf4j
public class QRController {

    @GetMapping(value = "/qr", produces = MediaType.IMAGE_PNG_VALUE)
    public ResponseEntity<byte[]> generateQRCode(@RequestParam("url") String url) {
        try {
            // Generate a 250x250 QR code image for the provided URL
            byte[] qrImage = QRCodeGenerator.generateQRCodeImage(url, 250, 250);
            return ResponseEntity.ok().contentType(MediaType.IMAGE_PNG).body(qrImage);
        } catch (WriterException | IOException e) {
            log.error("Failed to generate QR code message: {}, rootCause: ", e.getMessage(), e.getCause());
            return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).build();
        }
    }
}