SpringBoot - QR generator API

application.properties

server.port=3000
server.ssl.certificate=/Users/mayankc/Work/source/certs/cert.pem
server.ssl.certificate-private-key=/Users/mayankc/Work/source/certs/key.pem

QrApplication.java

package com.example.qr;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.embedded.tomcat.TomcatProtocolHandlerCustomizer;
import org.springframework.context.annotation.Bean;
import java.util.concurrent.Executors;

@SpringBootApplication
public class QrApplication {

  public static void main(String[] args) {
    SpringApplication.run(QrApplication.class, args);
  }

  @Bean
  public TomcatProtocolHandlerCustomizer<?> protocolHandlerVirtualThreadExecutorCustomizer() {
    return protocolHandler -> {
      protocolHandler.setExecutor(Executors.newVirtualThreadPerTaskExecutor());
    };
  }
}

QrController.java

package com.example.qr;

import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.http.ResponseEntity;
import org.springframework.http.HttpStatus;
import org.springframework.http.HttpHeaders;
import org.springframework.web.bind.annotation.RestController;
import java.util.Optional;
import com.example.qr.QrRequest;
import com.example.qr.QrGenerator;

@RestController
public class QrController {

  @PostMapping("/qr")
  public ResponseEntity handleRequest(@RequestBody QrRequest qrRequest) {
    if(qrRequest.getUrlToEmbed() == null) {
      return new ResponseEntity<>(HttpStatus.BAD_REQUEST);
    }

    try {
      HttpHeaders httpHeaders = new HttpHeaders();
      httpHeaders.add(HttpHeaders.CONTENT_TYPE, "image/png");
      return new ResponseEntity<byte[]>(
         QrGenerator.generateQR(qrRequest.getUrlToEmbed(), 512, 512), 
         httpHeaders,
         HttpStatus.OK);
    } catch (Exception e) {
      return new ResponseEntity<>(HttpStatus.INTERNAL_SERVER_ERROR);
    }
  }
}

QrGenerator.java

package com.example.qr;

import java.io.ByteArrayOutputStream;
import java.io.IOException;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.WriterException;
import com.google.zxing.client.j2se.MatrixToImageConfig;
import com.google.zxing.client.j2se.MatrixToImageWriter;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;

public class QrGenerator {

  public static byte[] generateQR(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();
    MatrixToImageConfig con = new MatrixToImageConfig() ;

    MatrixToImageWriter.writeToStream(bitMatrix, "PNG", pngOutputStream, con);
    byte[] pngData = pngOutputStream.toByteArray();
    return pngData;
  }
}

QrRequest.java

package com.example.qr;

public class QrRequest {
  private String urlToEmbed;

  public String getUrlToEmbed() {
    return this.urlToEmbed;
  }

  public void setUrlToEmbed(String urlToEmbed) {
    this.urlToEmbed = urlToEmbed;
  }
}