第一个Hibernate应用

1.创建配置文件

hibernate.cfg.xml：

<?xml version="1.0" encoding="utf-8" ?><!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd"><hibernate-configuration>  <session-factory >    <property name="dialect">org.hibernate.dialect.MySQLDialect</property>    <property name="connection.driver_class">com.mysql.jdbc.Driver</property>    <property name="connection.url">jdbc:mysql://localhost:3306/sampledb</property>    <property name="connection.username">root</property>    <property name="connection.password">1234</property>    <property name="show_sql">true</property>    <mapping resource="com.mypack/Customer.hbm.xml" />  </session-factory></hibernate-configuration>

2.创建持久化类

Customer.java：

package com.mypack;import java.util.Date;public class Customer  implements java.io.Serializable {     private long id;     private String name;     private Date registeredTime;     private int age;     private char sex;     private boolean married;     private String description;    public Customer() {    }    public Customer(String name, int age) {        this.name = name;        this.age = age;    }    public Customer(String name, Date registeredTime, int age, char sex, boolean married, String description) {       this.name = name;       this.registeredTime = registeredTime;       this.age = age;       this.sex = sex;       this.married = married;       this.description = description;    }       public long getId() {        return this.id;    }        private void setId(long id) {        this.id = id;    }    public String getName() {        return this.name;    }        public void setName(String name) {        this.name = name;    }        public Date getRegisteredTime() {        return this.registeredTime;    }        public void setRegisteredTime(Date registeredTime) {        this.registeredTime = registeredTime;    }        public int getAge() {        return this.age;    }        public void setAge(int age) {        this.age = age;    }    public char getSex() {        return this.sex;    }        public void setSex(char sex) {        this.sex = sex;    }        public boolean isMarried() {        return this.married;    }        public void setMarried(boolean married) {        this.married = married;    }    public String getDescription() {        return this.description;    }        public void setDescription(String description) {        this.description = description;    }       public String toString() {             StringBuffer buffer = new StringBuffer();      buffer.append(getClass().getName()).append("@").append(Integer.toHexString(hashCode())).append(" [");      buffer.append("name").append("='").append(getName()).append("' ");      buffer.append("registeredTime").append("='").append(getRegisteredTime()).append("' ");      buffer.append("age").append("='").append(getAge()).append("' ");      buffer.append("married").append("='").append(isMarried()).append("' ");      buffer.append("description").append("='").append(getDescription()).append("' ");      buffer.append("]");            return buffer.toString();     }}

注：Hibernate要求持久化类必须提供一个不带参数的默认构造方法。

3.创建数据库Schema

drop table if exists CUSTOMERS;create table CUSTOMERS (ID bigint not null auto_increment, NAME varchar(15) not null unique, REGISTERED_TIME timestamp, AGE integer not null check (AGE>10), SEX char(1), IS_MARRIED bit, DESCRIPTION text, primary key (ID));create index IDX_REGISTERED_TIME on CUSTOMERS (REGISTERED_TIME);

4.创建对象-关系映射文件

Customer.hbm.xml：

<?xml version="1.0"?><!DOCTYPE hibernate-mappingPUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN""http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"><hibernate-mapping>  <class name="com.mypack.Customer" table="CUSTOMERS" >        <id name="id" type="long" column="ID" >      <meta attribute="scope-set">private</meta>      <generator class="native"/>    </id>    <property name="name" type="string" >      <meta attribute="use-in-tostring">true</meta>      <column name="NAME" length="15" not-null="true" unique="true" />    </property>        <property name="registeredTime" type="timestamp" >      <meta attribute="use-in-tostring">true</meta>      <column name="REGISTERED_TIME" index="IDX_REGISTERED_TIME" sql-type="timestamp" />    </property>             <property name="age" type="int">      <meta attribute="use-in-tostring">true</meta>      <column name="AGE" check="AGE>10" not-null="true"/>    </property>        <property name="sex" type="char" column="SEX"/>        <property name="married" type="boolean" column="IS_MARRIED">      <meta attribute="use-in-tostring">true</meta>    </property>    <property name="description" type="string">       <meta attribute="use-in-tostring">true</meta>       <column name="DESCRIPTION" sql-type="text"/>    </property>  </class> </hibernate-mapping>

注：在<class>元素中，<id>子元素必须存在且只能存在一次，必须先定义<id>子元素，再定义<property>子元素。

<id>子元素设定持久化类的OID和表的主键的映射，<property>子元素设定类的属性和表的字段的映射。

5.通过Hibernate API操作数据库

package com.mypack;import org.hibernate.*;import org.hibernate.cfg.Configuration;import java.io.*;import java.sql.Time;import java.util.*;public class BusinessService{  public static SessionFactory sessionFactory;  static{     try{      Configuration config = new Configuration().configure();      config.addClass(Customer.class);      StandardServiceRegistryBuilder builder = new StandardServiceRegistryBuilder().applySettings(config.getProperties());      sessionFactory = config.buildSessionFactory(builder.build());    }catch(RuntimeException e){e.printStackTrace();throw e;}  }  public void saveCustomer(Customer customer){    Session session = sessionFactory.openSession();    Transaction tx = null;    try {      tx = session.beginTransaction();      session.save(customer);      tx.commit();    }catch (RuntimeException e) {      if (tx != null) {        tx.rollback();      }      throw e;    } finally {      session.close();    }  }  public Customer loadCustomer(Long id){    Session session = sessionFactory.openSession();    Transaction tx = null;    try {      tx = session.beginTransaction();      Customer customer=(Customer)session.get(Customer.class,id);      tx.commit();      return customer;    }catch (RuntimeException e) {      if (tx != null) {        tx.rollback();      }      throw e;    } finally {      session.close();    }  }  public void printCustomer(Customer customer){    System.out.println(customer);  }  public void test(){    Customer customer=new Customer();    customer.setName("Tom");    customer.setAge(new Integer(21));    customer.setSex(new Character('M'));    customer.setMarried(new Boolean(false));    customer.setDescription("I am very honest.");    saveCustomer(customer);    customer=loadCustomer(customer.getId());    printCustomer(customer);  }  public static void main(String args[]){    new BusinessService().test();    sessionFactory.close();  }}