[JAVA] Generate barcode with Spring Boot

things to do

I want to create a one-dimensional barcode with the values entered in the form You can create barcodes and QR codes using a library called ZXing. https://github.com/zxing/zxing

This time, it is assumed that a one-dimensional barcode (CODE_39) will be output on the detail screen.

Addition of ZXing library

Add ZXing library to pom.xml Specify javase when developing with Java SE Specify android for development on Android Use commons-codec for Base64 encoding separately from Zxing library

pom.xml

<dependencies>
	<dependency>
		<groupId>com.google.zxing</groupId>
		<artifactId>javase</artifactId>
		<version>3.4.0</version>
	</dependency>
	<devendency>
		<groupId>com.google.zxing</groupId>
		<artifactId>core</artifactId>
		<version>3.4.0</version>		
	</devendency>
	<devendency>
		<groupId>commons-codec</groupId>
		<artifactId>commons-codec</artifactId>
		<version>1.10</version>
	</devendency>
</dependencies>

Preparation

Prepare Entity and Repository

UsersEntity.java

@Entity
@Table(name="Users")
public class UsersEntity{
  @Id
  private Integer id;
  private String name;

  public Integer getId(){
    return id;
  }

  public String getName(){
    return name;
  }
}

UsersRepository.java

import com.example.entities.UsersEntity;
import org.springframework.data.jpa.repository.JpaRepository;

public interface UsersRepository extends JpaRepository<UsersEntity, Integer>{
}

Describe Controller

It is assumed that there is a list screen and a detail screen, and a barcode is output on the detail screen.

UsersController.java

Controller
public class UsersController {
	@Autowired
	private UsersRepository usersRepository;

	@RequestMapping("/user/index")
	public String index(Model model) {
		List<UsersEntity> users = usersRepository.findAll();
		model.addAttribute("userlist",users);
		return "view/user/index";
	}

	@GetMapping("/user/{id}")
	public String show(@PathVariable Integer id, Model model) {
		UsersEntity user = usersRepository.findById(id).get();
		model.addAttribute("user",user);
		barcode(String.valueOf(id), model);
		return "/view/user/show";
	}

	@GetMapping
	public String barcode(@PathVariable(value="id") String id, Model model) {
		try {
			byte[] res = toByteArray(id);
			String encodedStr64 = Base64.encodeBase64String(res);
			model.addAttribute("dataUrl", encodedStr64);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return "Image/data";
	}

	private byte[] toByteArray(String contents) throws IOException, WriterException{
		BarcodeFormat format = BarcodeFormat.CODE_39;
		int width = 180;
		int height = 40;	
		Hashtable<EncodeHintType, Object> hints = new Hashtable<EncodeHintType, Object>();
		hints.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.M);

		try (ByteArrayOutputStream output = new ByteArrayOutputStream()){
			Code39Writer writer = new Code39Writer();
			BitMatrix bitMatrix = writer.encode(contents, format, width, height, hints);
			MatrixToImageWriter.writeToStream(bitMatrix,  "png",  output);
			return output.toByteArray();
		}
	}

View description

index.html

<tr th:each="users : ${userlist}">
	<td th:text="${users.id}"></td>
	<td th:text="${users.name}"></td>
	<td><a th:href="@{/user/{id}(id=${users.id})}">Details</a></td>
</tr>

show.html

<tr th:object="${user}">
	<td th:text="*{id}"></td>
	<td th:text="*{name}"></td>
	<td><img th:src="|data:image/png;base64, ${dataUrl}|" class="barcode"></td>
</tr>

Contents that I was allowed to refer to

https://qiita.com/rubytomato@github/items/187e277b964b14f77179 https://weblabo.oscasierra.net/java-zxing-2/