Dodatkowa wersja z DataSource

PC27-SklepSpring/src/main/java/sklep/alternatywne_dostepy_do_bazy/ProductController_v0.java

+package sklep.alternatywne_dostepy_do_bazy;
+
+import org.springframework.stereotype.Controller;
+import org.springframework.web.bind.annotation.GetMapping;
+import org.springframework.web.bind.annotation.RequestMapping;
+import org.springframework.web.bind.annotation.ResponseBody;
+
+import java.sql.*;
+
+@Controller
+@RequestMapping("/alt0")
+public class ProductController_v0 {
+    // W tej wersji samodzielnie nawiązuję połączenie z bazą
+
+    @GetMapping(produces = "text/plain;charset=UTF-8")
+    @ResponseBody
+    public String readAll() {
+        StringBuilder sb = new StringBuilder("Lista produktów:\n");
+        try(Connection c = DriverManager.getConnection("jdbc:postgresql://localhost:5432/sklep", "kurs", "abc123");
+            Statement stmt = c.createStatement();
+            ResultSet rs = stmt.executeQuery("SELECT * FROM products ORDER BY product_id")) {
+
+            while(rs.next()) {
+                sb.append("* produkt ")
+                        .append(rs.getString("product_name"))
+                        .append(" za cenę ")
+                        .append(rs.getBigDecimal("price"))
+                        .append('\n');
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+            sb.append("Błąd: ").append(e);
+        }
+        return sb.toString();
+    }
+}

PC27-SklepSpring/src/main/java/sklep/alternatywne_dostepy_do_bazy/ProductController_v1.java

 package sklep.alternatywne_dostepy_do_bazy;
 
+import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.RequestMapping;
 import org.springframework.web.bind.annotation.ResponseBody;
 
+import javax.sql.DataSource;
 import java.sql.*;
 
 @Controller
 @RequestMapping("/alt1")
 public class ProductController_v1 {
+    @Autowired
+    private DataSource dataSource;
+    // W tej wersji Spring dostarcza nam obiekt DataSource na podstawie konfiguracji w pliku application.properties
 
     @GetMapping(produces = "text/plain;charset=UTF-8")
     @ResponseBody
     public String readAll() {
         StringBuilder sb = new StringBuilder("Lista produktów:\n");
-        try(Connection c = DriverManager.getConnection("jdbc:postgresql://localhost:5432/sklep", "kurs", "abc123");
+        try(Connection c = dataSource.getConnection();
             Statement stmt = c.createStatement();
             ResultSet rs = stmt.executeQuery("SELECT * FROM products ORDER BY product_id")) {
 
@@ -28,7 +33,7 @@ public class ProductController_v1 {
             }
         } catch (SQLException e) {
             e.printStackTrace();
-            sb.append("Błąd: " + e);
+            sb.append("Błąd: ").append(e);
         }
         return sb.toString();
     }