05_ServiceClass

Code-Dateien

DateinameAktion
CODECode_Bank.zipDownload
CODECode_Pizza.zipDownload
CODECode_Urlaub.zipDownload

Videos

DateinameAktion
VIDEOVideo_Pizza_EAbspielen
VIDEOVideo_Urlaub_DAbspielen

Lernmaterialien

Service

Service Class

@Service (org.springframework.stereotype.Service)

A service class is a class that contains the business logic of your application.

👉 It sits between:

  • the controller (input / UI / API)
  • and the data layer (repository / database)

Simple idea

  • Entity (PizzaOrder) → data
  • Service → logic (what to do with the data)

What the service does

  • creates orders
  • calculates price
  • applies rules (business logic)

For your pizza example:

  • in a small practice program, the service class can hold an ArrayList<PizzaOrder>
  • in a real database application, the service class should not permanently hold the data itself; the data is usually stored in a repository/database
001.png 
@Service
public class PizzaOrderService {
    private ArrayList<PizzaOrder> orders;

    public PizzaOrderService() {
        orders = new ArrayList<>(1000);
    }

    @Override
    public String toString() {
        return orders.stream()
                .map(order -> order.toString())
                .collect(Collectors.joining("\n"));
    }
}

Faker Data

https://github.com/DiUS/java-faker

https://www.javadoc.io/doc/com.github.javafaker/javafaker/latest/com/github/javafaker/Faker.html

Faker is a Java class from a library that creates fake test data.

It is used when you want sample values for testing, for example:

  • names
  • cities
  • countries
  • phone numbers
  • prices
  • random text

So instead of typing test data by hand, Faker generates it for you.

Faker faker = new Faker();
System.out.println(faker.address().country());
System.out.println(faker.address().cityName());
System.out.println(faker.number().randomDouble(2, 10, 50));


Austria
Vienna
24.75

pom.xml

        <dependency>
            <groupId>com.github.javafaker</groupId>
            <artifactId>javafaker</artifactId>
            <version>1.0.2</version>
        </dependency>
002.png 
    public void fillTestData(int anz) {
        PizzaOrder p;
        Faker faker;
        String[] PIZZAS = {"Margherita", "Salami", "Tonno", "Hawaii", "Funghi", "Diavolo"};
        String[] SIZES = { "Small", "Medium", "Large", "Family" };

        faker = new Faker();
        orders.clear();

        for (int i = 0; i < anz; i++) {
            p = new PizzaOrder();
            p.setOrderId((long) (i + 1));

            p.setOrderDate(LocalDate.now().minusDays(faker.number().numberBetween(0, 30)));
            p.setPizza(PIZZAS[faker.number().numberBetween(0, PIZZAS.length)]);
            p.setSize(SIZES[faker.number().numberBetween(0, SIZES.length)]);
            p.setPrice(faker.number().randomDouble(2, 6, 20));
            p.setQuantity(faker.number().numberBetween(1, 6));
            p.setGarlic(faker.bool().bool());

            orders.add(p);
        }
            firstName = faker.address().firstName();
            openingDate = LocalDate.now().minusDays((int) Math.random() * 3650);
            accountType = accounttypes[faker.random().nextInt(0, accounttypes.length - 1)];
            amount = faker.number().randomDouble(2, 0, 50000);
            active = faker.bool().bool();
            a = new Account(firstName, openingDate, accountType, amount, active);
            accounts.add(a);

Test

    @Test
    public void testFillTestData() {
        PizzaOrderService orders = new PizzaOrderService();
        System.out.println(orders);
    }

GIT!!!