前言：创建EntityManager对象，需要先创建创建EntityManagerFactory对象
方式一：直接通过persistenceUnitName创建
1 String persistenceUnitName = "Jpa-1"; 2 EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory(persistenceUnitName);
方式二：通过persistenceUnitName和properties一起创建
1 String persistenceUnitName = "Jpa-1"; 2 Map<String, Object> properties = new HashMap<String, Object>(); 3 properties.put("hibernate.show_sql", false); 4 EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory(persistenceUnitName, properties);
2.创建一个测试增删改查的JPA项目
1 package com.jtfr.jpa.test; 2 3 import javax.persistence.EntityManager; 4 import javax.persistence.EntityManagerFactory; 5 import javax.persistence.EntityTransaction; 6 import javax.persistence.Persistence; 7 8 import org.junit.After; 9 import org.junit.Before; 10 import org.junit.Test; 11 12 public class JpaTest { 13 14 private EntityManagerFactory entityManagerFactory; 15 private EntityManager entityManager; 16 private EntityTransaction transaction; 17 18 @Before 19 public void create(){ 20 entityManagerFactory = Persistence.createEntityManagerFactory("Jpa-1"); 21 entityManager = entityManagerFactory.createEntityManager(); 22 transaction = entityManager.getTransaction(); 23 transaction.begin(); 24 } 25 26 @Test 27 public void testFind(){ 28 System.out.println("没问题"); 29 } 30 31 @After 32 public void end(){ 33 transaction.commit(); 34 entityManager.close(); 35 entityManagerFactory.close(); 36 } 37 }
