obsługa koszyka

PC37-SklepSpring/src/main/java/sklep/basket/Basket.java

+package sklep.basket;
+
+import java.math.BigDecimal;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import sklep.model.Product;
+
+public class Basket {
+    private final Map<Integer, ProductInBasket> elementy = new HashMap<>();
+    
+    public synchronized void addProduct(Product product, int quantity) {
+        if(elementy.containsKey(product.getId())) {
+            // jeśli w słowniku jest już taki element, to tylko zwiększamy ilość
+            elementy.get(product.getId()).increaseQuantity(quantity);
+        } else {
+            // jeśli jeszcze nie ma, to tworzymy
+            elementy.put(product.getId(),
+                    new ProductInBasket(product.getId(), product.getProductName(), product.getPrice(), quantity));
+        }
+    }
+
+    public synchronized void addProduct(Product product) {
+        // "domyślną ilością, o którą zwiększamy, jest 1"
+        addProduct(product, 1);
+    }
+
+    public synchronized void removeProduct(int productId) {
+        elementy.remove(productId);
+    }
+    
+    public synchronized Collection<ProductInBasket> getElements() {
+        return Collections.unmodifiableCollection(elementy.values());
+    }
+
+    public synchronized BigDecimal getTotalValue() {
+        return getElements().stream()
+                .map(ProductInBasket::getValue)
+                .reduce(BigDecimal.ZERO, BigDecimal::add);
+    }
+    
+    @Override
+    public synchronized String toString() {
+        return "Koszyk o rozmiarze " + getElements().size()
+                + " i wartości " + getTotalValue();
+    }
+    
+}

PC37-SklepSpring/src/main/java/sklep/basket/BasketConfiguration.java

+package sklep.basket;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+import jakarta.servlet.http.HttpSession;
+import jakarta.servlet.http.HttpSessionEvent;
+import jakarta.servlet.http.HttpSessionListener;
+
+@Configuration
+public class BasketConfiguration {
+    // Adnotacja Configuration powoduje, że:
+    // - Spring tworzy obiekt tej klasy (BasketConfiguration)
+    // - dla każdej meody oznaczonej @Bean uruchamia tę metodę, a jej wynik rejestruje jako bean
+    // - gdy typ wynikowy "znaczy dla Springa coś specjalnego", to Spring weźmie to pod uwagę,
+    //   właśnie w ten sposób często podaje się Springowi elementy konfiguracji
+    
+    @Bean
+    HttpSessionListener createListener() {
+        return new HttpSessionListener() {
+            @Override
+            public void sessionCreated(HttpSessionEvent se) {
+                HttpSession sesja = se.getSession();
+//		        sesja.setMaxInactiveInterval(30); // pół minuty i sesja wygasa
+//		        System.out.println("sessionCreated " + sesja.getId());
+                Basket basket = new Basket();
+                sesja.setAttribute("basket", basket);
+            }
+        };
+    }
+
+}

PC37-SklepSpring/src/main/java/sklep/basket/ProductInBasket.java

+package sklep.basket;
+
+import java.math.BigDecimal;
+import java.util.Objects;
+
+public class ProductInBasket {
+    private final int productId;
+    private String productName;
+    private BigDecimal price;
+    private int quantity;
+    
+    public ProductInBasket(int productId, String productName, BigDecimal price, int quantity) {
+        this.productId = productId;
+        this.productName = productName;
+        this.price = price;
+        this.quantity = quantity;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    public int getQuantity() {
+        return quantity;
+    }
+
+    public void setQuantity(int quantity) {
+        this.quantity = quantity;
+    }
+
+    public int getProductId() {
+        return productId;
+    }
+
+    public String getProductName() {
+        return productName;
+    }
+
+    @Override
+    public String toString() {
+        return "ElementKoszyka [productId=" + productId + ", productName=" + productName + ", price=" + price
+                + ", quantity=" + quantity + "]";
+    }
+    
+    @Override
+    public int hashCode() {
+        return Objects.hash(price, productId, productName, quantity);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        ProductInBasket other = (ProductInBasket) obj;
+        return Objects.equals(price, other.price) && productId == other.productId
+                && Objects.equals(productName, other.productName) && quantity == other.quantity;
+    }
+
+    public BigDecimal getValue() {
+        return price.multiply(BigDecimal.valueOf(quantity));
+    }
+
+    public void increaseQuantity(int change) {
+        quantity += change;
+    }
+    
+}

PC37-SklepSpring/src/main/java/sklep/controller/ProductController.java

@@ -11,7 +11,9 @@ import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.SessionAttribute;
 
+import sklep.basket.Basket;
 import sklep.model.Product;
 import sklep.repository.ProductRepository;
 
@@ -66,6 +68,18 @@ public class ProductController {
         }
     }
     
+    @GetMapping("/{id}/add-to-basket")
+    public String addToBasket(@PathVariable("id") Integer productId,
+                              @SessionAttribute Basket basket) {
+        Optional<Product> product = productRepository.findById(productId);
+        if(product.isPresent()) {
+            basket.addProduct(product.get());
+        } else {
+            System.err.println("Nieznany produkt dodawany do koszyka: " + productId);
+        }
+        return "redirect:/products";
+    }
+    
     @GetMapping(produces="text/plain")
     @ResponseBody
     public String getProductsTxt() {