Integrating Spring and Hibernate

The Spring framework provides extensive support for data access through the use of support classes (JdbcDaoSupport, JdbcTemplate etc.), and extensive exception hierarchy to wrap any platform specific SQLException into an exception in the spring exception hierarchy. Additionally Spring framework also provides good support for integrating with ORM technologies like Hibernate and iBatis etc.

 

Prerequisite jars for this example

• commons-logging-1.1.1.jar
• hibernate3.jar
• dom4j-1.6.1.jar
• ojdbc14.jar
• commons-collections-3.2.jar
• log4j-1.2.15.jar
• commons-dbcp.jar
• commons-pool.jar
• spring.jar
• cglib-nodep-2.1_3.jar
• antlr-2.7.6.jar
• jta.jar

Example Code

1. Create the entity bean: The bean here represents a simple stock quote

package com.vaani.entity;

public class StockQuoteBean {
private String quoteId;

private String stockSymbol;

private String name;

public String getQuoteId() {
return quoteId;
}

public void setQuoteId(String quoteId) {
this.quoteId = quoteId;
}

public String getStockSymbol() {
return stockSymbol;
}

public void setStockSymbol(String stockSymbol) {
this.stockSymbol = stockSymbol;
}

public String getName() {
return name;
}

public void setName(String name) {
this.name = name;
}
}

2. Create a Hibernate Mapping file (hbm) for the entity:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="com.vaani.entity.StockQuoteBean" table="STOCK_QUOTES" lazy="false">
<id name="quoteId" column="quote_id">
 <generator class="assigned" />
</id>

<property name="stockSymbol">
 <column name="stock_symbol" />
</property>
<property name="name">
 <column name="name" />
</property>
</class>
</hibernate-mapping>

The one important thing to note here is that in the declaration, a [lazy="false"] has been added to the mapping for the stockquote bean. The reason for this is that in hibernate 3, lazy initialization is turned on by default. This raises a problem when used with spring's HibernateCallback. The spring HibernateTemplate.execute() by default closes any open sessions upon completion. When used with lazy initialization you may get a LazyInitializationException like the following

org.hibernate.LazyInitializationException: could not initialize proxy - no Session

If you want to use lazy initialization with HibernateCallback, you will have to use this within a transaction context. The javadoc for HibernateTemplate specifies this explicitly.

Note that operations that return an Iterator (i.e. iterate) are supposed
to be used within Spring-driven or JTA-driven transactions (with
HibernateTransactionManager, JtaTransactionManager, or EJB CMT). Else, the
Iterator won't be able to read results from its ResultSet anymore, as the
underlying Hibernate Session will already have been closed.

Lazy loading will also just work with an open Hibernate Session, either within a
transaction or within OpenSessionInViewFilter/Interceptor. Furthermore, some
operations just make sense within transactions, for example: contains, evict,
lock, flush, clear.

3. Create the service class: The service class simply acts as an intermediary between the client and the DAO classes.

package com.vaani.springhibernate;

import com.vaani.entity.StockQuoteBean;
import com.vaani.hibernate.dao.PortfolioDAO;

public class PortfolioService {
private PortfolioDAO portfolioDAO;

public StockQuoteBean getStockQuote(String id) {
StockQuoteBean result = portfolioDAO.getStockQuote(id);
return result;
}

public void updateStockQuote(StockQuoteBean stockQuoteBean) {
portfolioDAO.updateStockQuote(stockQuoteBean);
}

public PortfolioDAO getPortfolioDAO() {
return portfolioDAO;
}

public void setPortfolioDAO(PortfolioDAO portfolioDAO) {
this.portfolioDAO = portfolioDAO;
System.out.println("Setting portfolio DAO to : " + portfolioDAO.getClass());
}

}

4. The DAO interface:

package com.vaani.hibernate.dao;

import com.vaani.entity.StockQuoteBean;

public interface PortfolioDAO {
public StockQuoteBean getStockQuote(String id);
public void updateStockQuote(StockQuoteBean bean);
public StockQuoteBean getStockQuote_hibernateTemplate(String id);
public void updateStockQuote_hibernateTemplate(StockQuoteBean bean);
}

5. The DAO Classes: The DAO classes shows the different ways in which the Hibernate calls can be made using the Spring support classes. There are three primary ways in which these calls can be made

1. Using the HibernateCallback
   
2. Using the HibernateTemplate directly
   
3. Using the hibernate native calls using Session

Spring also provides two different ways to create the Data access objects that interact with Hibernate.

1. Using Composition, with HibernateTemplate
   
2. Using Inheritance by extending HibernateDaoSupport

All these methods will be explained when used in the following sections.

Using HibernateTemplate

package com.vaani.hibernate.dao;

import java.sql.SQLException;
import java.util.List;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.springframework.orm.hibernate3.HibernateCallback;
import org.springframework.orm.hibernate3.HibernateTemplate;

import beans.StockQuoteBean;

public class PortfolioDAOTemplate implements PortfolioDAO{
private HibernateTemplate hibernateTemplate;

public PortfolioDAOTemplate() {
System.out.println("Init transaction dao");
}


public StockQuoteBean getStockQuote(final String id) {

HibernateCallback callback = new HibernateCallback() {
   public Object doInHibernate(Session session) throws HibernateException, SQLException {
    return session.load(StockQuoteBean.class, id);
   }
  };
return (StockQuoteBean) hibernateTemplate.execute(callback);
}

 public void updateStockQuote(final StockQuoteBean StockQuoteBean) {
  HibernateCallback callback = new HibernateCallback() {
   public Object doInHibernate(Session session) throws HibernateException, SQLException {
    session.saveOrUpdate(StockQuoteBean);
    return null;
   }
  };
  hibernateTemplate.execute(callback);
  
 }

 public void updateStockQuote_hibernateTemplate(StockQuoteBean StockQuoteBean) {
  hibernateTemplate.update(StockQuoteBean);

 }
 public StockQuoteBean getStockQuote_hibernateTemplate(String id) {
  List<StockQuoteBean> transactions = hibernateTemplate.find("from beans.StockQuoteBean stockQuoteBean where stockQuoteBean.quoteId=?", id);
  return transactions.get(0);
 }


public HibernateTemplate getHibernateTemplate() {
return hibernateTemplate;
}


public void setHibernateTemplate(HibernateTemplate hibernateTemplate) {
this.hibernateTemplate = hibernateTemplate;
}



}

This class shows how to use the HibernateTemplate to make calls to Hibernate. The getStockQuote() and updateStockQuote() methods use HibernateCallback class, note that when using HibernateCallback, it is necessary to either do it in a transactional context or turn off lazy initialization. While the getStockQuote_hibernateTemplate() and updateStockQuote_hibernateTemplate() make calls using hibernateTemplate directly. Also note that the parameters to the getStockQuote(), and updateStockQuote() methods are marked final.

 

Using HibernateDaoSupport

package com.vaani.hibernate.dao;

import java.util.List;

import org.hibernate.Query;
import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

import beans.StockQuoteBean;

public class PortfolioDAOSupport extends HibernateDaoSupport implements PortfolioDAO {

public void updateStockQuote(StockQuoteBean stockQuoteBean) {
  Query query = getSession().createQuery("update beans.StockQuoteBean set stockSymbol=? where quoteId=?");
  query.setString(0, stockQuoteBean.getStockSymbol());
  query.setString(1, stockQuoteBean.getQuoteId());
  query.executeUpdate();
 }
 public StockQuoteBean getStockQuote(String id) {
  Query query = getSession().createQuery("from beans.StockQuoteBean stockQuoteBean where stockQuoteBean.quoteId=?");
  query.setString(0, id);
  List results = query.list();
  if(results == null || results.size() == 0) {
   throw new RuntimeException("No result");
  }
  return (StockQuoteBean)results.get(0);
 }

public void updateStockQuote_hibernateTemplate(StockQuoteBean StockQuoteBean) {
getHibernateTemplate().update(StockQuoteBean);

}
public StockQuoteBean getStockQuote_hibernateTemplate(String id) {
List<StockQuoteBean> transactions = getHibernateTemplate().find("from beans.StockQuoteBean stockQuoteBean where stockQuoteBean.quoteId=?", id);
return transactions.get(0);
}

}

This class uses HibernateDaoSupport to get instances of HibernateTemplate, and the Hibernate Session. The getStockQuote() and updateStockQuote() in this class make calls to hibernate session directly.

 

6. The application context

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd">

 <bean id="portfolioDAOTemplate" class="com.vaani.hibernate.dao.PortfolioDAOTemplate">
  <property name="hibernateTemplate" ref="hibernateTemplate" />
 </bean>
 
 <bean id="portfolioDAOSupport" class="com.vaani.hibernate.dao.PortfolioDAOSupport">
  <property name="hibernateTemplate" ref="hibernateTemplate" />
 </bean>

<bean id="portfolioService" class="com.vaani.springhibernate.PortfolioService">
<property name="portfolioDAO" ref="portfolioDAOSupport"></property>
</bean>

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />
<property name="url" value="jdbc:oracle:thin:@localhost:1521/xe" />
<property name="username" value="appUser" />
<property name="password" value="password" />
</bean>
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
  <property name="dataSource" ref="dataSource" />
  <property name="mappingResources">
   <list>
    <value>stockquote.hbm.xml</value>
   </list>
  </property>

  <property name="hibernateProperties">
   <props>
    <prop key="hibernate.dialect">org.hibernate.dialect.Oracle9Dialect</prop>
    <prop key="hibernate.show_sql">true</prop>
    <prop key="hibernate.generate_statistics">true</prop>
   </props>
  </property>
 </bean>
 <bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate">
  <property name="sessionFactory" ref="sessionFactory" />
 </bean>
</beans>

• The SessionFactory is defined with the datasource and mapping-resources. The hibernate specific properties are defined under the hibernateProperties property.
  
• The HibernateTemplate uses are reference to the SessionFactory.
  
• The HibernateTemplate is used as a reference to the DAO classes.
  
• The porfolioService bean in uses a reference to the PortfolioDAO, which can be switched between the dao.PortfolioDAOSupport and dao.PortfolioDAOTemplate beans

7 . The main class

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;

import com.vaani.entity.StockQuoteBean;


public class SpringHibernateTest {


public static void main(String[] args) {
Resource resource = new FileSystemResource("applicationContext.xml");
BeanFactory factory = new XmlBeanFactory(resource);

PortfolioService portfolioService = (PortfolioService) factory.getBean("portfolioService");

StockQuoteBean result = portfolioService.getStockQuote("123");
System.out.println(result.getStockSymbol());

empResult.setStockSymbol("GOOG");
portfolioService.updateStockQuote(result);
}


}