1.创建maven工厂导入依赖
junit junit4.12 test org.hibernate hibernate-entitymanager5.0.12.Final org.hibernate hibernate-c3p05.0.12.Final mysql mysql-connector-java5.1.49
2.在resources下创建META-INF文件夹,然后在创建persistence.xml配置文件
org.hibernate.jpa.HibernatePersistenceProvider
3.编写实体类完成 表和实体类的映射关系
@Entity
@Table(name = "t_user")
public class User {
public User() {
}
public User(Integer id, String userName, Integer age) {
this.id = id;
this.userName = userName;
this.age = age;
}
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private Integer id;
@Column(name = "user_name")
private String userName;
private Integer age;
set..
get..
}
4.编写测试类进行测试
public class JpaTest {
private static EntityManagerFactory entityManagerFactory;
static {
entityManagerFactory = Persistence.createEntityManagerFactory("myJPA");
}
//提取成一个工具类
public static EntityManager createEntityManager(){
return entityManagerFactory.createEntityManager();
}
@Test
public void testSave() throws IOException {
//1.加载配置创建工厂对象
EntityManagerFactory entityManagerFactory = Persistence.createEntityManagerFactory("myJPA");
//2.工厂创建实体管理对象
EntityManager entityManager = entityManagerFactory.createEntityManager();
EntityTransaction transaction = entityManager.getTransaction();
//3.管理对象开启事务
transaction.begin();
try {
User user = new User(null,"张大宝2",18);
//4.管理对象完成CRUD
entityManager.persist(user); //保存操作
//5.管理对象完成事务提交
transaction.commit();
}catch (Exception e){
//6.管理对象回滚事务
transaction.rollback();
}finally {
//7.管理对象释放事务
if(entityManager != null){
entityManager.close();
}
if(entityManagerFactory != null){
entityManagerFactory.close();
}
}
}
//查询方法
@Test
public void find(){
//2.工厂创建实体管理对象
EntityManager entityManager = JpaTest.createEntityManager();
//立即查询sql
User user = entityManager.find(User.class, 1);
System.out.println(user);
//延迟查询sql
User user2 = entityManager.getReference(User.class, 1);
System.out.println(user2);
if(entityManager != null){
entityManager.close();
}
}
//更新方法
@Test
public void update(){
EntityManager entityManager = JpaTest.createEntityManager();
EntityTransaction transaction = entityManager.getTransaction();
User user = entityManager.getReference(User.class, 1);
user.setUserName("new王大宝");
transaction.begin();
User merge = entityManager.merge(user);
transaction.commit();
if(entityManager != null){
entityManager.close();
}
}
//删除方法
@Test
public void remove(){
EntityManager entityManager = JpaTest.createEntityManager();
EntityTransaction transaction = entityManager.getTransaction();
transaction.begin();
User user = entityManager.getReference(User.class, 1);
entityManager.remove(user);
transaction.commit();
if(entityManager != null){
entityManager.close();
}
}
}
提示
表是不用自己创建的,只需要指定好数据库即可
1.JPQL基本使用语法,JPQL和SQL语法区别是JPQL操作的都是对象名和属性,SQL操作表和字段
public class JpqlTest {
@Test
public void find(){
EntityManager entityManager = JpaTest.createEntityManager();
//查询全部
System.out.println("====================查询全部====================");
String jpql="from com.yujie.model.User";
Query query = entityManager.createQuery(jpql);
List resultList = query.getResultList();
for (Object o : resultList) {
System.out.println(o);
}
//统计个数
System.out.println("====================统计个数====================");
jpql="select count(id) from com.yujie.model.User";
query = entityManager.createQuery(jpql);
Object singleResult = query.getSingleResult();
System.out.println(singleResult);
//分页查询
System.out.println("====================分页查询====================");
jpql="From com.yujie.model.User";
query = entityManager.createQuery(jpql);
query.setFirstResult(0);
query.setMaxResults(5);
List resultLimit = query.getResultList();
for (Object o : resultLimit) {
System.out.println(o);
}
//倒序查询
System.out.println("====================倒序查询====================");
jpql="from com.yujie.model.User order by id desc";
query = entityManager.createQuery(jpql);
List resultDesc= query.getResultList();
for (Object o : resultDesc) {
System.out.println(o);
}
//条件查询
System.out.println("====================条件查询====================");
jpql="from com.yujie.model.User where id=? and userName=?";
query = entityManager.createQuery(jpql);
query.setParameter(1,1);
query.setParameter(2,"张大宝");
List resultList1 = query.getResultList();
for (Object o : resultList1) {
System.out.println(o);
}
//模糊查询
System.out.println("====================模糊查询====================");
jpql="from com.yujie.model.User where userName like ?";
query = entityManager.createQuery(jpql);
query.setParameter(1,"老%");
List resultLike = query.getResultList();
for (Object o : resultLike) {
System.out.println(o);
}
}
}
打印结果
====================查询全部====================
Hibernate: select user0_.id as id1_0_, user0_.age as age2_0_, user0_.user_name as user_nam3_0_ from t_user user0_
User{id=1, userName='张大宝', age=18}
User{id=2, userName='老六', age=18}
====================统计个数====================
Hibernate: select count(user0_.id) as col_0_0_ from t_user user0_
2
====================分页查询====================
Hibernate: select user0_.id as id1_0_, user0_.age as age2_0_, user0_.user_name as user_nam3_0_ from t_user user0_ limit ?
User{id=1, userName='张大宝', age=18}
User{id=2, userName='老六', age=18}
====================倒序查询====================
Hibernate: select user0_.id as id1_0_, user0_.age as age2_0_, user0_.user_name as user_nam3_0_ from t_user user0_ order by user0_.id desc
User{id=2, userName='老六', age=18}
User{id=1, userName='张大宝', age=18}
====================条件查询====================
Hibernate: select user0_.id as id1_0_, user0_.age as age2_0_, user0_.user_name as user_nam3_0_ from t_user user0_ where user0_.id=? and user0_.user_name=?
User{id=1, userName='张大宝', age=18}
====================模糊查询====================
Hibernate: select user0_.id as id1_0_, user0_.age as age2_0_, user0_.user_name as user_nam3_0_ from t_user user0_ where user0_.user_name like ?
User{id=2, userName='老六', age=18}
