Hibernate访问多个数据库

今天开会讨论的时候. 项目中要用到通过Hibernate访问多个数据库..以为系统集成了其他子系统,所以几个不同数据库进行数据访问和存取..

 

在有限的时间内,做一个比较简单的例子..便于以后参考:有些地方,未考虑,请大家拍砖..

 

 

Hibernate访问多个数据库的设计思路：其实就是利用 Hibernate中config = new
Configuration().configure(configFile);

 

可以加载不同数据库配置信息的原理，编写一个通过的 数据库操作类，再编写一个数据库管理程序[map],

将加载的数据库连接实例put早数据库管
理程序中，

 

具体实现见下面：

 

在做测试之前,需要在oracle和mysql中建立表Student;

见表语句:

oracle:

Create table Student(
      id varchar2(10) not null,
      name varchar2(10)not null,
      sex varchar2(4) not null,
      age number 
)

commit;

 

mySql:

create table `student` (
	`id` varchar (30),
	`name` varchar (30),
	`sex` varchar (12),
	`age` int (4)
); 
commit;

 

 

 

这里针对于两个不同数据库..一个文件是对oracle数据库操作,取名叫oracle.cfg.xml

另外一个针对于MySql数据库操作..取名叫做mySql.cfg.xml

 

oracle.cfg.xml配置如下:

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

<session-factory>
	<property name="connection.url">
		jdbc:oracle:thin:@localhost:1521:ORCL
	</property>
	<property name="dialect">
		org.hibernate.dialect.Oracle9Dialect
	</property>
	<property name="connection.username">scott</property>
	<property name="connection.password">tiger</property>
	<property name="connection.driver_class">oracle.jdbc.driver.OracleDriver</property>
	<property name="show_sql">true</property>
    <property name="format_sql">true</property>
    <mapping resource = "pack/java/model/Student.hbm.xml"/>
</session-factory>

</hibernate-configuration>

 

 

mySql.cfg.xml配置如下:'

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                                         "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>
 <session-factory name="">
  <property name="connection.url">jdbc:mysql://127.0.0.1/mysql</property>
  <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
  <property name="connection.username">root</property>
  <property name="connection.password">password</property>
  <property name="connection.driver_class">com.mysql.jdbc.Driver</property>
  <property name="show_sql">true</property>
  <property name="format_sql">true</property>
  <mapping resource = "pack/java/model/Student.hbm.xml"/>
 </session-factory>
</hibernate-configuration>

 

 

之后,建立一个Student VO对象.

package pack.java.model;

import java.io.Serializable;
/**
 * Student VO * @author Administrator
 *
 */
public class Student implements Serializable{
	
	private static final long serialVersionUID = 1034231412171686357L;
	
	private String id;
	private String name;
	private String sex;
	private long age;
	
	public String getId() {
		return id;
	}
	public void setId(String id) {
		this.id = id;
	}
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public String getSex() {
		return sex;
	}
	public void setSex(String sex) {
		this.sex = sex;
	}
	public long getAge() {
		return age;
	}
	public void setAge(long age) {
		this.age = age;
	}
	
	public Student() {
		super();
		// TODO Auto-generated constructor stub
	}
	
	public Student(String id, String name, String sex, long age) {
		super();
		this.id = id;
		this.name = name;
		this.sex = sex;
		this.age = age;
	}
}

 、建立 一个DataBaseManager 管理SessionManager；

package pack.java.basedao;

import java.util.HashMap;
/**
 * 建立 一个DataBaseManager 管理SessionManager；
 * 用于存放多个SessionFactory；
 * @author Administrator
 *
 */
public class DataBaseManager extends HashMap{
	private static final long serialVersionUID = 2939313139367007154L;
	private static DataBaseManager dbinstance = new DataBaseManager();

	public static DataBaseManager getDbinstance() {
		return dbinstance;
	}
	
	public static void setDbinstance(DataBaseManager dataBaseManager){
		DataBaseManager.dbinstance = dataBaseManager;
	}
	
	public SessionManager get(Object key){
		return (SessionManager) super.get(key);
	}

	@SuppressWarnings("unchecked")
	@Override
	public Object put(Object key, Object value) {
		// TODO Auto-generated method stub
		return super.put(key, value);
	}
}

 

、 建立一个SessionManager；从SessionFactory中获取Session，以及定义一些，基本的CRUD的操作;

 

package pack.java.basedao;

import java.io.Serializable;
import java.util.List;

import org.hibernate.Criteria;
import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
/**
 * 建立一个SessionManager；从SessionFactory中
 * 获取Session，以及定义一些，基本的CRUD的操作;
 * @author Administrator
 *
 */
public class SessionManager{
	private Configuration configuration = null;
	private SessionFactory sessionFactory = null;
	private Session session = null;
	
	public Criteria createCriteria(Class clazz){
		return session.createCriteria(clazz);
	}
	
	public void buildSession(){
		sessionFactory  = configuration.buildSessionFactory();
		session = sessionFactory.openSession();
	}
	
	public SessionManager(String configFile){
		configuration = new Configuration().configure(configFile);
		buildSession();
	}
	
	public Session getSession(){
		return session;
	}
	
	public void save(Object obj){
		Transaction transaction = session.beginTransaction();
		session.save(obj);
		transaction.commit();
	}
	
	public void update(Object obj){
		Transaction transaction = session.beginTransaction();
		session.update(obj);
		transaction.commit();
	}
	
	@SuppressWarnings("unchecked")
	public <T>List<T> queryAll(Class clazz){
		return session.createQuery("from "+clazz.getName()).list();
	}
	
	@SuppressWarnings("unchecked")
	public Object queryObjectById(Class clazz,Serializable id){
		return session.load(clazz, id);
	}
	
	public void delete(Object obj){
		Transaction transaction = session.beginTransaction();
		session.delete(obj);
		transaction.commit();
	}
	
	@SuppressWarnings("unchecked")
	public void delete(Class clazz,Serializable id){
		Transaction transaction = session.beginTransaction();
		this.delete(this.queryObjectById(clazz, id));
		transaction.commit();
	}
	
	@SuppressWarnings("unchecked")
	public <T>List<T> queryObjectsByHql(String hql,Object...objects){
		Query query = session.createQuery(hql);
		if(objects!= null && objects.length>0){
			for(int i = 0;i<objects.length;i++){
				query.setParameter(i, objects[i]);
			}
		}
		return query.list();
	}
}

 

 

最后，就是测试针对多个数据库进行操作了,

具体代码如下:

package pack.java.test;

import pack.java.basedao.DataBaseManager;
import pack.java.basedao.SessionManager;
import pack.java.model.Student;
/**
 * 测试多个数据源;
 * @author ZhouHaiTao
 *
 */
public class TestHibernateDataSource {
	DataBaseManager baseManager = null;
	public void testDataSource(){
		setDatabase();
		
		SessionManager mysqlSessionManager =  baseManager.get("mysql");
		//Session mysqlSession = mysqlSessionManager.getSession();
		Student student1 = new Student();
		student1.setId("100");
		student1.setName("周海涛");
		student1.setAge(22);
		student1.setSex("男");
		mysqlSessionManager.save(student1);
		System.out.println("成功添加到MySql数据库中!");
		
		SessionManager oracleSessionManager = baseManager.get("oracle");
		//Session oracleSession = oracleSessionManager.getSession();
		Student student2 = new Student();
		student2.setId("101");
		student2.setName("张三");
		student2.setAge(20);
		student2.setSex("女");
		oracleSessionManager.save(student2);
		System.out.println("成功添加到Oracle数据库中!");
	}
	
	public void setDatabase(){
		SessionManager oracleSessionManager = new SessionManager("oracle.cfg.xml");
		SessionManager mysqlSessionManager  = new SessionManager("mysql.cfg.xml");
		
		baseManager = DataBaseManager.getDbinstance();
		baseManager.put("mysql", mysqlSessionManager);
		baseManager.put("oracle", oracleSessionManager);
	}
	
	public static void main(String[] args) {
		new TestHibernateDataSource().testDataSource();
	}
}

 

 

运行之后，生成两条插入的sql语句..

 

Hibernate:
    insert
    into
        STUDENT
        (NAME, SEX, AGE, ID)
    values
        (?, ?, ?, ?)

成功添加到MySql数据库中!

Hibernate:
    insert
    into
        STUDENT
        (NAME, SEX, AGE, ID)
    values
        (?, ?, ?, ?)

成功添加到Oracle数据库中!

 

分别查询oracle和Mysql数据库,

发现数据都已经插入进来了,操作成功!