ProductController_v2 - wersja bez StringBuildera, ze streamem

PC27-SklepSpring/src/main/java/sklep/alternatywne_dostepy_do_bazy/ProductController_v2.java

 package sklep.alternatywne_dostepy_do_bazy;
 
-import java.util.List;
+import java.util.stream.Collectors;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
@@ -22,33 +22,21 @@ public class ProductController_v2 {
     @GetMapping(produces = "text/plain;charset=UTF-8")
     @ResponseBody
     public String readAll() {
-        List<Product> products = em.createNamedQuery("Product.findAll", Product.class).getResultList();
-        StringBuilder sb = new StringBuilder("Lista produktów:\n");
-        for(Product product : products) {
-            sb.append(" * ")
-                    .append(product.getProductName())
-                    .append(" za cenę ")
-                    .append(product.getPrice())
-                    .append('\n');
-        }
-        return sb.toString();
+        return em.createNamedQuery("Product.findAll", Product.class)
+                .getResultStream()
+                .map(product -> product.getProductName() + " za cenę " + product.getPrice() + "\n")
+                .collect(Collectors.joining());
     }
 
     @GetMapping(path = "/{id}", produces = "text/plain;charset=UTF-8")
     @ResponseBody
     public String readOne(@PathVariable("id") Integer productId) {
         Product product = em.find(Product.class, productId);
-        StringBuilder sb = new StringBuilder();
         if(product != null) {
-            sb.append("Znaleziony produkt:\n")
-                    .append(product.getProductName())
-                    .append(" za cenę ")
-                    .append(product.getPrice())
-                    .append('\n');
+            return product.getProductName() + " za cenę " + product.getPrice();
         } else {
-            sb.append("Nie ma produktu o numerze ").append(productId);
+            return "Nie ma produktu o numerze " + productId;
         }
-        return sb.toString();
     }
 
     @GetMapping(path = "/szukaj", produces = "text/plain;charset=UTF-8")
@@ -57,17 +45,11 @@ public class ProductController_v2 {
         TypedQuery<Product> query = em.createQuery("SELECT p FROM Product p WHERE productName = :nazwa", Product.class);
         query.setParameter("nazwa", name);
         Product product = query.getSingleResult();
-        StringBuilder sb = new StringBuilder();
         if(product != null) {
-            sb.append("Znaleziony produkt:\n")
-                    .append(product.getProductName())
-                    .append(" za cenę ")
-                    .append(product.getPrice())
-                    .append('\n');
+            return product.getProductName() + " za cenę " + product.getPrice();
         } else {
-            sb.append("Nie ma produktu o nazwie ").append(name);
+            return "Nie ma produktu o nazwie " + name;
         }
-        return sb.toString();
     }
 
 }