Coder's Block

Problem:

Here’s the code

@Transactional
void outer(){
   inner1();    // @Transactional
   inner2();    // @Transactional
}

Both inner methods are transactional. Now, what I wanted to happen was, when outer() is called and if inner2() is rolled back, inner1() too should roll back.

Solution:

Use the NESTED option for the @Transactional annotation. As in the documentation, this is what happens when you do that,

Execute within a nested transaction if a current transaction exists, behave like PROPAGATION_REQUIRED else.

And PROPAGATION_REQUIRED or REQUIRED option  means,

Support a current transaction, create a new one if none exists.

Based on that the code changes as follows,

@Transactional(propagation = Propagation.NESTED)
void outer(){
   inner1();    // @Transactional
   inner2();    // @Transactional
}

You can read about the other options in Spring Doc. I found another decent explanation here.

The steps below guides how to set up the back end of a Java Webapp on Tomcat while using Spring with Hibernate as the ORM.

Configure Connection String

In the /WEB-INF/classes/conf/jdbc.properties, we store the connection info,

jdbc.driverClassName=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost/JTest
jdbc.username=root
jdbc.password=admin
hib.dialect=org.hibernate.dialect.MySQLDialect
Configure Spring for Hibernate related beans: SessionFactory, Transaction Manager and HibernateTemplate
In the /WEB-INF/classes folder have the applicationContext.xml file.
<beans>
<!-- ========================= HIBERNATE CONFIG ========================= -->
<!-- Configurer that replaces ${...} placeholders with values from a properties file -->
<!-- (in this case, JDBC-related settings for the dataSource definition below) -->
<bean id="propertyConfigurer">
<property name="location"><value>conf/jdbc.properties</value></property>
</bean>
<!-- Local DataSource that works in any environment -->

<!-- Note that DriverManagerDataSource does not pool; it is not intended for production -->
<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
<property name="driverClassName"><value>${jdbc.driverClassName}</value></property>
<property name="url"><value>${jdbc.url}</value></property>
<property name="username"><value>${jdbc.username}</value></property>
<property name="password"><value>${jdbc.password}</value></property>
</bean>
<!-- Hibernate SessionFactory -->
<bean id="sessionFactory" class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
<property name="dataSource"><ref local="dataSource"/></property>
<property name="mappingResources">
<list>
<value>Product.hbm.xml</value>
</list>
</property>
<property name="hibernateProperties">
<props>
<prop key="hibernate.dialect">${hib.dialect}</prop>
<prop key="hibernate.show_sql">true</prop>
</props>
</property>
</bean>
<!-- Transaction manager for a single Hibernate SessionFactory (alternative to JTA) -->
<bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
<property name="sessionFactory"><ref local="sessionFactory"/></property>
</bean>
<bean id="hibernateTemplate" class="org.springframework.orm.hibernate3.HibernateTemplate">
<property name="sessionFactory">
<ref bean="sessionFactory"/>
</property>
</bean>
</beans>
HibernateTemplate is a Spring class to bridge between Hibernate. More details here
Configure the Persistence classes and DAO classes
In the <beans> tag of applicationContext, have the following
<!-- ========================= APP BEANS ========================= -->
<bean id="Product" class="gunith.jtest.model.impl.BasicProduct"></bean>
<bean id="ProductDao" class="gunith.jtest.dao.hibernate.ProductHibernateDao">
<property name="hibernateTemplate">
<ref bean="hibernateTemplate"/>
</property>
</bean>
Create the Mapping File
This is the definition of spring beans related to the business logic. BasicProduct is a persistence POJ class, the realization of an interface Product. The 2 are mapped in the /WEB-INF/classes/Product.hbm.xml. (Here we have another class called MeasurableProduct)
<hibernate-mapping>
<class name="gunith.jtest.model.Product" table="product">
<id name="id">
<generator class="native"></generator>
</id>
<discriminator column="type"></discriminator>
<property name="name"></property>
<property name="price"></property>
<many-to-one name="brand" class="gunith.jtest.model.Brand" column="brand_id" lazy="false"></many-to-one>
<subclass name="gunith.jtest.model.impl.BasicProduct" discriminator-value="0"></subclass>
<subclass name="gunith.jtest.model.impl.MeasurableProduct" discriminator-value="1">
<property name="unit"></property>
</subclass>
</class>
</hibernate-mapping>
Create The DAO
The Database operations of Product is done by the gunith.jtest.dao.hibernate.ProductHibernateDao.  It extends org.springframework.orm.hibernate3.support.HibernateDaoSupport. (Note that there’s a setter for hibernateTemplate in spring config)
public abstract class ProductHibernateDao extends HibernateDaoSupport {
/** Saves an object in the DB */
public Serializable add(Object obj) {
   return getHibernateTemplate().save(obj);
}
/** Gets all objects of a given class */
public List getAllObjects(Class entityClass) {
   List all = getHibernateTemplate().loadAll(entityClass);
   return all;
}
}
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While I was deploying Spring, I got the following Exception,

java.security.AccessControlException: access denied (java.util.PropertyPermission cglib.debugLocation read)

The fix for such “access denied” is as follows,

• Open [CATALINA_HOME]/conf/policy.d/04webapps.policy (ON UBUNTU)
• Add the following to that file inside the grant{} block

permission java.util.PropertyPermission "cglib.debugLocation","read";

Likewise, for

access denied (java.lang.RuntimePermission getProtectionDomain)

Add this,

permission java.lang.RuntimePermission "getProtectionDomain";