Hibernate学习笔记(一)快速入门

<dependency>
      <groupId>org.hibernate</groupId>
      <artifactId>hibernate-core</artifactId>
      <version>5.6.6.Final</version>
 </dependency>
<dependency>
   <groupId>mysql</groupId>
    <artifactId>mysql-connector-java</artifactId>
    <version>5.1.29</version>
</dependency>
<dependency>
            <groupId>org.slf4j</groupId>
            <artifactId>slf4j-simple</artifactId>
            <version>1.7.5</version>
</dependency>

<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
        "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <!-- 这里配置数据相关的信息驱动类  -->
        <property name="connection.driver_class">org.h2.Driver</property>
        <!-- JDBC  -->
        <property name="connection.url">jdbc:h2:mem:db1;DB_CLOSE_DELAY=-1</property>
        <property name="connection.username">sa</property>
        <property name="connection.password"/>
  
        <!-- JDBC connection pool (use the built-in) 连接池大小1 -->
        <property name="connection.pool_size">1</property>
        <!-- SQL dialect 指定方言 不同的数据库有不同的方言 -->
        <property name="dialect">org.hibernate.dialect.H2Dialect</property>
        <!-- Disable the second-level cache 禁用缓存  -->
        <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>
        <!-- Echo all executed SQL to stdout -->
        <property name="show_sql">true</property>
        <!-- 自动根据实体来创建表-->
        <property name="hbm2ddl.auto">create</property>
  
        <!--在这里指定映射关系-->
        <mapping resource="org/hibernate/tutorial/hbm/Event.hbm.xml"/>
    </session-factory>
</hibernate-configuration>

package org.hibernate.tutorial.hbm;
import java.util.Date;
public class Event {
 private Long id;
 private String title;
 private Date date;
 public Event() {
  // this form used by Hibernate
 }
 public Event(String title, Date date) {
  // for application use, to create new events
  this.title = title;
  this.date = date;
 }
 public Long getId() {
  return id;
 }
 private void setId(Long id) {
  this.id = id;
 }
 public Date getDate() {
  return date;
 }
 public void setDate(Date date) {
  this.date = date;
 }
 public String getTitle() {
  return title;
 }
 public void setTitle(String title) {
  this.title = title;
 }
}

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="org.hibernate.tutorial.hbm">
  <!-- 这里将实体类和表名进行绑定 -->
    <class name="Event" table="EVENTS">
        <id name="id" column="EVENT_ID">
        <!--设定ID产生策略-->
            <generator class="increment"/>
        </id>
        <property name="date" type="timestamp" column="EVENT_DATE"/>
        <property name="title"/>
    </class>
</hibernate-mapping>

package org.hibernate.tutorial.hbm;
import java.util.Date;
import java.util.List;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistry;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import junit.framework.TestCase;
/**
 * 
 *
 * 这个会启动setUp 再执行testBasicUsage，再执行 tearDown
 */
public class NativeApiIllustrationTest extends TestCase {
 private SessionFactory sessionFactory;
 
  
 @Override
 protected void setUp() throws Exception {
  // A SessionFactory 在一个应用只设置一次
  final StandardServiceRegistry registry = new StandardServiceRegistryBuilder()
    .configure() // configure可以指定Hibernate的配置文件, 这里让Hibernate去找默认的配置文件
    .build();
  try {
   sessionFactory = new MetadataSources( registry ).buildMetadata().buildSessionFactory();
  }catch (Exception e) { 
            // registry  会被SessionFactory锁销毁,我们会在构建Session可能遇到一些问题
            // 所以要手动销毁它
   StandardServiceRegistryBuilder.destroy( registry );
  }
 }
 @Override
 protected void tearDown() throws Exception {
        // 执行完毕,关闭sessionFactory 
  if ( sessionFactory != null ) {
   sessionFactory.close();
  }
 }
 @SuppressWarnings("unchecked")
 public void testBasicUsage() {
  // 创建一对Event,开启一个Session,
  Session session = sessionFactory.openSession();
        // 开启事务
  session.beginTransaction();
        // 插入一条记录
  session.save( new Event( "Our very first event!", new Date() ) );
        // 插入一条记录
  session.save( new Event( "A follow up event", new Date() ) );
        // 提交事务
  session.getTransaction().commit();
        // 关闭session
  session.close();
  
  session = sessionFactory.openSession();
  session.beginTransaction();
        // 从数据库里面拉取记录,这个语法被称为HQL
  List result = session.createQuery( "from Event" ).list();
  for ( Event event : (List<Event>) result ) {
   System.out.println( "Event (" + event.getDate() + ") : " + event.getTitle() );
  }
        // 提交事务
  session.getTransaction().commit();
        // 关闭
  session.close();
 }
}

create table Contact (
    id integer not null,
    first varchar(255),
    last varchar(255),
    middle varchar(255),
    notes varchar(255),
    starred boolean not null,
    website varchar(255),
    primary key (id)
)

@Entity(name = "Contact")
public static class Contact {
 @Id
 private Integer id;
 private Name name;
 private String notes;
 private URL website;
 private boolean starred;
 //Getters and setters are omitted for brevity
}
@Embeddable
public class Name {
 private String firstName;
 private String middleName;
 private String lastName;
 // getters and setters omitted
}

@Entity(name = "Person")
public static class Person {
 @Id
 private Long id;
 @ElementCollection
 private List<String> phones = new ArrayList<>();
    
 //Getters and setters are omitted for brevity
}
Person person = entityManager.find( Person.class, 1L );
//Throws java.lang.ClassCastException: org.hibernate.collection.internal.PersistentBag cannot be cast to java.util.ArrayList
ArrayList<String> phones = (ArrayList<String>) person.getPhones()

@Entity
@Table(name = "person")
public class Person {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY )
    private Long id;
    private String name;
    private String nickName;
    private String address;
 
    // 这个字段用于将Java的日期类型映射到数据库的类型
    @Temporal(TemporalType.TIMESTAMP )
    private Date createdOn;
    @Version
    private int version;
    //Getters and setters are omitted for brevity
}

<mapping class="org.example.tutorial.hbm.entity.Person"></mapping>

int insertedEntities = session.createQuery(
 "insert into Partner (id, name) " +
 "select p.id, p.name " +
 "from Person p ")
.executeUpdate();

session.createQuery("update from Person set address = :address  where id = :id")
                .setParameter("id",2L).
                 setParameter("address","测试修改").executeUpdate();
session.createQuery("delete from Person where id = :id").setParameter("id",1L).executeUpdate();

List list =  session.createQuery(" select p  from Person p where id = :id").setParameter("id",2L).list();
List<Person> personList = session.createQuery(" select p  from Person p where address is null", Person.class).list();

public class JPATest extends TestCase {
    private EntityManagerFactory entityManagerFactory;
    @Override
    protected void setUp() throws Exception {
        entityManagerFactory = Persistence.createEntityManagerFactory( "org.hibernate.tutorial.jpa" );
    }
    // createQuery的语法与我们上文介绍的相同
    public void test(){
        entityManagerFactory.createEntityManager().createQuery("select p from Person p where id = :id").setParameter("id",2L);
    }
    @Override
    protected void tearDown() throws Exception {
        entityManagerFactory.close();
    }
}