Spring + Hibernate Usefuls

The below custom BaseDAOHibernate class should reduce most of the common DAO related coding. The search and searchAdvanced will be used to wrap the select query related method calls.

package com.xmp.web2.dao;


public class BaseDAOHibernate extends HibernateDaoSupport implements DAO {

private static final Log LOGGER = LogFactory.getLog(BaseDAOHibernate.class);

protected DataSource dataSource;

public void setDataSource(DataSource dataSource) {
this.dataSource = dataSource;
}

public void saveObject(final Object object) {
getHibernateTemplate().saveOrUpdate(object);
}

public Object getObject(final Class clazz, final Serializable id) {
Object object = getHibernateTemplate().get(clazz, id);

return object;
}

public List getObjects(final Class clazz) {
return getHibernateTemplate().loadAll(clazz);
}

public void removeObject(final Class clazz, final Serializable id) {
getHibernateTemplate().delete(getObject(clazz, id));
}

public List findObject(final Class clazz, final String columnName, final String articleID) {
return getHibernateTemplate().find("from " + clazz.getName() + " tableAlias where tableAlias." + columnName + " in ( " + articleID + " )");
}

/**
* Accepts a HQL and ordered map of parameters.
*
* @param query
* @param parameters
* @return
*/
public List search(String query, LinkedHashMap parameters) throws xmpWebException {
boolean keepSessionOpen=false;
return search(query, parameters, keepSessionOpen);
}

/**
* Accepts a HQL and ordered map of parameters.
* The caller of this method should explicitly close the session.
* @param query
* @param parameters
* @parm keepSessionOpen -boolean to instruct if the session should be closed or not.
* @return
*/
protected List search(String query, LinkedHashMap parameters, boolean keepSessionOpen) throws xmpWebException {
List objList = null;
Session session = null;
try {
 if (LOGGER.isInfoEnabled()) {
  LOGGER.info(new StringBuilder().append("Searching ( query = ").append(query).append(" ,parameters =").append(parameters).append(")").toString());
 }
 session = getHibernateTemplate().getSessionFactory().openSession();
 Query queryObj = session.createQuery(query);
  queryObj.setCacheable(true);

 if (parameters != null) {
  for (Iterator iter = parameters.keySet().iterator(); iter.hasNext();) {
   String key = (String) iter.next();
   Object value = parameters.get(key);
   queryObj.setParameter(key, value);
  }
 }
 objList = queryObj.list();

} catch (Exception e) {
 String msg = new StringBuilder("Search failed ( query = ").append("Searching ( query = ").append(query).append(" ,parameters =").append(parameters).append(")").toString();
 LOGGER.error(msg, e);
 throw new xmpWebException(msg, e);
} finally {
 if (!keepSessionOpen) {
  if (session != null && session.isOpen())
   session.close();
 }
}
return objList;
}

/**
* Accepts a HQL and ordered map of parameters. Useful with pagination as it
* accepts pageNo and pagesize.
*
* @param query
* @param parameters
* @param pageNo - The starting page number
* @param pageSize - The max record size.
* @return
*/
protected List searchAdvanced(final String query, final LinkedHashMap parameters, final int pageNo, final int pageSize) throws xmpWebException {

boolean keepSessionOpen = false;
return searchAdvanced(query, parameters, pageNo, pageSize, keepSessionOpen);
}
/**
* Accepts a HQL and ordered map of parameters. Useful with pagination as it
* accepts pageNo and pagesize.
*
* @param query
* @param parameters
* @param pageNo - The starting page number
* @param pageSize - The max record size.
* @param keepSessionOpen - boolean to identify if session needs to be kept open or not.
* @return
*/
protected List searchAdvanced(final String query, final LinkedHashMap parameters, final int pageNo, final int pageSize, boolean keepSessionOpen) throws xmpWebException {
if (LOGGER.isInfoEnabled()) {
 LOGGER.info(new StringBuilder("Searching with ( query = ").append(query).append(" ,parameters =").append(parameters).append(" ,pageNo =").append(pageNo).append(" ,pageSize= ").append(
   pageSize).append(" )").toString());
}
Session session = null;
try {
 session = getHibernateTemplate().getSessionFactory().openSession();
 Query queryObject = session.createQuery(query);
 // queryObj.setCacheable(true);
 if (parameters != null) {
  for (Iterator iter = parameters.keySet().iterator(); iter.hasNext();) {
   String key = (String) iter.next();
   Object value = parameters.get(key);
   queryObject.setParameter(key, value);
  }
 }
 queryObject.setMaxResults((pageSize < msg =" new" query = ").append(query).append(" parameters =").append(parameters).append(" pageno =").append(pageNo).append(" pagesize= ").append(      pageSize).append(">                                                                                             

------------------------------------------------------------------------------------------------------------------------------------------------------------------------ The above should solve most of the basic coding effort in DAO layer which we do 90% of the time. Spring+Hibernate Junit testing: Spring framework provides a nifty base class (AbstractTransactionalDataSourceSpringContextTests) that provides automatic transaction rollback, exposing a JDBC template to interact with the DB and auto wiring of beans.

Lets take a simple DAO class that save a User object to the database:

public class UserDaoImpl extends HibernateDaoSupport implements UserDao { public void save(User user) { getHibernateTemplate().save(user); } }

Now in order to test this you would write a test class as below extending from AbstractTransactionalDataSourceSpringContextTests class.

public class UserDaoTest extends AbstractTransactionalDataSourceSpringContextTests { private UserDao userDao; private SessionFactory sessionFactory = null; protected String[] getConfigLocations() { return new String[]{"test-spring-config.xml"}; } public void setUserDao(UserDao userDao) { this.userDao = userDao; } public void setSessionFactory(SessionFactory sessionFactory) { this.sessionFactory = sessionFactory; } /** * Test the save method * */ public void testSave(){ String query = "select count(*) from user where first_name = 'Firstname'"; int count = jdbcTemplate.queryForInt(query); assertEquals("A user already exists in the DB", 0, count); User user = new User(); user.setFirstName("Firstname"); userDao.saveUser(user); // flush the session so we can get the record using JDBC template SessionFactoryUtils.getSession(sessionFactory, false).flush(); count = jdbcTemplate.queryForInt(query); assertEquals("User was not found in the DB", 1, count); } }

The test class has to implement the protected String[] getConfigLocations() method from the base class and return a String array of Spring config files which will be used to initialize the Spring context. UserDao and SessionFactory properties are defined with the setter methods and the base class will take care of injecting them automatically from the Spring context. Auto wiring will not work if there are multiple objects implementing the same interface. In such a case you can remove the setter method and retrieve the object using the exposed applicationContext as below.

/** * Overridden method from base class which gets called automatically */ protected void onSetUpBeforeTransaction() throws Exception { super.onSetUpBeforeTransaction(); userDao = (UserDao) applicationContext.getBean("userDao"); }

The base class also exposes a JDBC template object (jdbcTemplate) that can be used to query data or setup test data in the database. Note that you need to have a data source and a transaction manager defined in your Spring config in order to use the AbstractTransactionalDataSourceSpringContextTests base class. The data source defined in the config file will be bound to the exposed JDBC template. In the testSave method first we verify there is no record in the User table where first name equals to 'Firstname' using the jdbc template object. Then we call the save method on the UserDao passing it a User object. Now we simple verify there is a record in the table where first name equals to 'Firstname'. Before running the query we flush the current Hibernate session to make sure jdbcTemplate can see the newly added record. Thats it and when the testSave method exits the current transaction will be rolled back and the record inserted to the User table will not be saved. This is great as your test database will always be at a know state at the start and end of a test method. The spring config file will like below (test-spring-config.xml) :

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>
<bean name="userDao" class="com.dao.UserDaoImpl">
<property name="sessionFactory">
   <ref bean="sessionFactory"/>
</property>
</bean>

<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource">
   <ref bean="dataSource"/>
</property>
<property name="mappingResources">
   <list>
       <value>hibernates/User.hbm.xml</value>
   </list>
</property>
<property name="hibernateProperties">
   <props>
       <prop key="hibernate.query.factory_class">org.hibernate.hql.classic.ClassicQueryTranslatorFactory</prop>
       <prop key="hibernate.dialect">org.hibernate.dialect.OracleDialect</prop>
   </props>
</property>
</bean>


<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
<property name="driverClassName" value="oracle.jdbc.driver.OracleDriver"/>
<property name="url" value="jdbc:oracle:thin:@localhost:1521:ORCL" />
<property name="username" value="test" />
<property name="password" value="test" />
</bean>


<bean id="txManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>

</beans>

Useful stuff: HQL many to many query for retreival from UserTask ut where :journal in elements(ut.journals)