Initial commit

src/main/java/jpa/EntityManagerHelper.java

@@ -0,0 +1,50 @@
+package jpa;
+
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.EntityManagerFactory;
+import jakarta.persistence.Persistence;
+
+public class EntityManagerHelper {
+
+    private static final EntityManagerFactory emf; 
+    private static final ThreadLocal<EntityManager> threadLocal;
+
+    static {
+        emf = Persistence.createEntityManagerFactory("dev");      
+        threadLocal = new ThreadLocal<EntityManager>();
+    }
+
+    public static EntityManager getEntityManager() {
+        EntityManager em = threadLocal.get();
+
+        if (em == null) {
+            em = emf.createEntityManager();
+            threadLocal.set(em);
+        }
+        return em;
+    }
+
+    public static void closeEntityManager() {
+        EntityManager em = threadLocal.get();
+        if (em != null) {
+            em.close();
+            threadLocal.set(null);
+        }
+    }
+
+    public static void closeEntityManagerFactory() {
+        emf.close();
+    }
+
+    public static void beginTransaction() {
+        getEntityManager().getTransaction().begin();
+    }
+
+    public static void rollback() {
+        getEntityManager().getTransaction().rollback();
+    }
+
+    public static void commit() {
+        getEntityManager().getTransaction().commit();
+    } 
+}

src/main/java/jpa/JpaTest.java

@@ -0,0 +1,42 @@
+package jpa;
+
+
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.EntityTransaction;
+
+public class JpaTest {
+
+
+	private EntityManager manager;
+
+	public JpaTest(EntityManager manager) {
+		this.manager = manager;
+	}
+	/**
+	 * @param args
+	 */
+	public static void main(String[] args) {
+			EntityManager manager = EntityManagerHelper.getEntityManager();
+
+		JpaTest test = new JpaTest(manager);
+
+		EntityTransaction tx = manager.getTransaction();
+		tx.begin();
+		try {
+
+			// TODO create and persist entity
+		} catch (Exception e) {
+			e.printStackTrace();
+		}
+		tx.commit();
+
+			
+   	 manager.close();
+		EntityManagerHelper.closeEntityManagerFactory();
+		System.out.println(".. done");
+	}
+
+
+
+
+}