Service Layer in Spring Data

Question

I'm building a small application in Spring and Spring Data JPA. I need serval layer. I don't know if I'm doing well.

Here is an example:
POJO

@Entity
public class Product {
 @Id
 @GeneratedValue
 private long Id;
 @NotBlank
 private String name;
 @NotNull
 private int price;
 public long getId() {
 return Id;
 }
 public String getName() {
 return name;
 }
 public int getPrice() {
 return price;
 }
 public void setId(long id) {
 Id = id;
 }
 public void setName(String name) {
 this.name = name;
 }
 public void setPrice(int price) {
 this.price = price;
 }
 @Override
 public String toString() {
 return "Product{" +
 "Id=" + Id +
 ", name='" + name + '\'' +
 ", price=" + price +
 '}';
 }
}

REPOSITORY

public interface ProductRepository extends CrudRepository<Product, Long> {
 Product findByName(String name);
 List<Product> getAllProducts();
 Product getProductById(String productId);
 void addProduct(Product product);
}

SERVICE

public interface ProductService {
 List<Product> getAllProducts();
 Product getProductById(String productId);
 void addProduct(Product product);
}

REPOSITORY IMPLEMENTATION

@Service
public class ProductServiceImpl implements ProductService {
 @Autowired
 private ProductRepository productRepository;
 @Override
 public List<Product> getAllProducts() {
 return productRepository.getAllProducts();
 }
 @Override
 public Product getProductById(String productId) {
 return productRepository.getProductById(productId);
 }
 @Override
 public void addProduct(Product product) {
 productRepository.addProduct(product);
 }
}

It is a good? Unless How create communication with database in Spring?

• Pawan: What is the benefit of having Service Interface here?
• New one: @Pawan The use of service interface here is that if someone has to deliver ProductServices in a different way i.e by using a different database or using different business logic then by implementing the interface gives a reason to return the same output without affecting the presentation layer.

Answer 1

Well if I'd review this I'd add the following:

• The Id field in Product could be renamed id to follow java convention
• Generally it's a good practice to have equals & hashcode methods overridden.

As for the database connection it depends on which Spring & database you are using, does it happen to be Spring Boot?

• Mazen Melouk: @MaciejDymarczyk No problem Then it's very simple, assuming you use a mysql database you need: 1. Add dependency <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> ` </dependency>` 2. Add connection properties in application.yml file spring.datasource.url= jdbc:mysql://localhost:3306/YOUR_DB_NAME spring.datasource.username=YOUR_USERNAME spring.datasource.password=YOUR_PASSWORD For more check this