In this post, we’ll learn how to generate barcodes and QR codes and expose them as an endpoint in the Spring Boot API.
· Prerequisites
· Overview
∘ Barcodes
∘ QR Codes
· Getting Started
∘ Add Dependencies
∘ Create a Service for Barcode and QR Code Generation
∘ Create a REST Controller
· Test the REST APIs
∘ Generate a QR Code
∘ Generate a Barcode
· Conclusion
· References
Prerequisites
This is the list of all the prerequisites:
Overview
Barcodes
A barcode or bar code is a method of representing data in a visual, machine-readable form. Initially, barcodes represented data by varying the widths, spacings, and sizes of parallel lines.
Types of Barcodes
1D Barcodes (Linear Barcodes): These are the traditional barcodes with parallel lines. They represent data using the width and spacing of the bars. Examples include:
- UPC (Universal Product Code): Used on most retail products.
- EAN (European Article Number): Similar to UPC, used internationally.
- Code 39: Often used in automotive and defense industries.
- Code 128: Used for shipping labels and packaging.
QR Codes
A QR code, quick-response code,[1] is a type of two-dimensional matrix barcode invented in 1994 by Masahiro Hara of Japanese company Denso Wave for labelling automobile parts.
Structure of QR Codes
- 2D Barcodes: QR codes (Quick Response codes) are two-dimensional codes with black squares arranged on a white grid. They can store significant data, including URLs, text, and other information.
How QR Codes Work
- Data Encoding: QR codes can encode various data types, including numeric, alphanumeric, binary, and Kanji characters. The data is converted into a binary format and then represented as a pattern of squares.
- QR Code Generation: QR code generation software converts the encoded data into a visual QR code format. It can be used with various libraries or online tools.
- Printing: The generated QR code can be printed on labels, packaging, or displayed on screens.
- A QR code scanner (often a smartphone camera or a dedicated QR code reader) captures the image of the QR code.
- The scanner analyzes the pattern of squares and converts it into a binary format.
- The binary data is then decoded back into the original information.
- Data Retrieval: The decoded data can be used to perform various actions, such as opening a URL in a web browser, displaying text, or adding a contact to a phone.
Getting Started
Let’s create a simple Spring Boot project from start.spring.io, with the following dependencies: Spring Web.
Add Dependencies
We’ll use the ZXing library for 1D Barcode and QR Code Generation.
Add the necessary dependencies for barcode and QR code generation to your pom.xml
<dependency>
<groupId>com.google.zxing</groupId>
<artifactId>javase</artifactId>
<version>3.4.4</version>
</dependency>
<dependency>
<groupId>com.google.zxing</groupId>
<artifactId>core</artifactId>
<version>3.4.4</version>
</dependency>Create a Service for Barcode and QR Code Generation
Create a service class to handle barcode and QR code generation.
@Service
public class BarcodeServiceImpl implements BarcodeService {
private static final String DEFAULT_IMAGE_FORMAT = "png";
@Override
public byte[] generateQRCode(String text) throws WriterException, IOException {
QRCodeWriter qrCodeWriter = new QRCodeWriter();
BitMatrix bitMatrix = qrCodeWriter.encode(text, BarcodeFormat.QR_CODE, 400, 400);
var qrcodeImage = MatrixToImageWriter.toBufferedImage(bitMatrix);
ByteArrayOutputStream pngOutputStream = new ByteArrayOutputStream();
ImageIO.write(qrcodeImage, DEFAULT_IMAGE_FORMAT, pngOutputStream);
return pngOutputStream.toByteArray();
}
@Override
public byte[] generateBarcode(String text) throws IOException, WriterException {
var height = 200;
var width = 400;
EnumMap<EncodeHintType, Object> hints = new EnumMap<>(EncodeHintType.class);
hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
MultiFormatWriter writer = new MultiFormatWriter();
BitMatrix bitMatrix = writer.encode(text, BarcodeFormat.EAN_13, width, height, hints);
BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
image.setRGB(x, y, bitMatrix.get(x, y) ? 0 : 0xFFFFFF);
}
}
ByteArrayOutputStream pngOutputStream = new ByteArrayOutputStream();
ImageIO.write(image, DEFAULT_IMAGE_FORMAT, pngOutputStream);
return pngOutputStream.toByteArray();
}
}Create a REST Controller
Finally, we create a controller that exposes endpoints for generating barcodes and QR codes.
@RestController
@RequestMapping(value = "/api")
public class BarcodeController {
private final BarcodeService barcodeService;
public BarcodeController(BarcodeService barcodeService) {
this.barcodeService = barcodeService;
}
@GetMapping(value = "/{type}", produces = MediaType.IMAGE_PNG_VALUE)
public ResponseEntity<byte[]> generateCode(@PathVariable String type, @RequestParam String text) {
byte[] code;
try {
return switch (type.toLowerCase()) {
case "qrcode" -> {
code = barcodeService.generateQRCode(text);
yield ResponseEntity.ok(code);
}
case "barcode" -> {
code = barcodeService.generateBarcode(text);
yield ResponseEntity.ok(code);
}
default -> ResponseEntity.badRequest().body(null); // 400 Bad Request for invalid type
};
} catch (WriterException | IOException e) {
return ResponseEntity.status(HttpStatus.INTERNAL_SERVER_ERROR).body(null);
}
}
}Test the REST APIs
Generate a QR Code
- URL:
http://localhost:8080/api/qrcode?text=helloword - Method:
GET - Response: A PNG image of the QR code.
Generate a Barcode
- URL:
http://localhost:8080/api/barcode?text=6923450657713 - Method:
GET - Response: A PNG image of the barcode
Conclusion
Well done! In this post, we learned how to generate barcodes and QR codes in a Spring Boot 3 REST API and expose them via endpoints.
The complete source code is available on GitHub.
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Thank you for reading!! See you in the next post.
