Question

I’m having issues properly setting up my Hibernate configuration. After trying to extend the HibernateDaoSupport into a GenericDao and extending those to class-specific daos, but when I call findByNamedQuery in my dao, getSession() throws an NPE.

When I tried switching to extending HibernateTemplate, the hibernateTemplate doesn’t get instantiated properly, and is still null:

java.lang.NullPointerException
at org.springframework.orm.hibernate3.support.HibernateDaoSupport.getSession(HibernateDaoSupport.java:143)
at com.jmt.hibernate.dao.GenericDaoImpl.findByNamedQuery(GenericDaoImpl.java)

What am I missing??

I used maven2 to build the project,
1. added the hibernate plugin into my pom.xml:

   <plugin>
    <groupId>org.codehaus.mojo</groupId>
    <artifactId>hibernate3-maven-plugin</artifactId>
    <version>3.0</version>

    <configuration>
        <components>
            <component>
            <name>hb2ddl</name>
            <implementation>jpaconfiguration</implementation>
            </component>
        </components>
        <componentProperties>
        <drop>true</drop>
        <outputfilename>output.sql</outputfilename>
        <format>false</format>
        <persistenceunit>MyEntityManager</persistenceunit>
        <ejb3>true</ejb3>
        </componentProperties>

    </configuration>
</plugin>

2. defined my entity manager in persistence.xml:

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd"
             version="2.0">

   <persistence-unit name="MyEntityManager" transaction-type="RESOURCE_LOCAL"> <!-- "JTA"> -->
      <provider>org.hibernate.ejb.HibernatePersistence</provider>
      <jta-data-source>java:/DefaultDS</jta-data-source>

        <class>com.jmt.model.UserEntity</class>

      <shared-cache-mode>ENABLE_SELECTIVE</shared-cache-mode>
      <validation-mode>CALLBACK</validation-mode>
      <properties>

            <property name="hibernate.archive.autodetection" value="class"/>
            <property name="hibernate.connection.driver_class" value="org.postgresql.Driver"/>
         <property name="hibernate.dialect" value="org.hibernate.dialect.PostgreSQLDialect"/><!-- org.hibernate.dialect.HSQLDialect" -->
         <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
         <property name="hibernate.connection.url"  value="${jdbc.url}"/>
         <property name="hibernate.connection.username" value="${jdbc.username}"/>
         <property name="hibernate.connection.password" value="${jdbc.password}"/>

      </properties>
   </persistence-unit>
</persistence>

3. wired up my daos in applicationContext.xml:

 <bean id="hibernateDaoSupport" abstract="true"
class="org.springframework.orm.hibernate3.support.HibernateDaoSupport">
<property name="sessionFactory" ref="sessionFactory"/>
</bean>
    <bean id="hibernateHelper" class="org.springframework.orm.hibernate3.HibernateTemplate" >
        <constructor-arg ref="sessionFactory"/>
    </bean>
    <bean id="transactionManager" class="org.springframework.orm.hibernate3.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory"/>
    <property name="hibernateManagedSession" value="true"/>
</bean>

    <bean class="com.jmt.model.UserEntity"/>

    <bean id="multipartResolver"
        class="org.springframework.web.multipart.commons.CommonsMultipartResolver" />

    <bean
        class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping">
        <property name="order" value="1" />
    </bean>

    <bean
        class="org.springframework.web.servlet.handler.BeanNameUrlHandlerMapping">
        <property name="order" value="2" />
    </bean>

    <bean id="messageSource" class="org.springframework.context.support.ResourceBundleMessageSource">
            <property name="basename"><value>messages</value></property>
    </bean>

    <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="org.postgresql.Driver"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="poolPreparedStatements" value="true"/>
        <property name="defaultAutoCommit" value="true"/>
        <property name="maxActive" value="100"/>
        <property name="maxIdle" value="30"/>
        <property name="maxWait" value="1000"/>
        <property name="removeAbandoned" value="true"/>
        <property name="removeAbandonedTimeout" value="60"/>
        <property name="logAbandoned" value="true"/>
        <property name="testOnBorrow" value="false"/>
        <property name="testWhileIdle" value="true"/>
        <property name="timeBetweenEvictionRunsMillis" value="10000"/>
        <property name="minEvictableIdleTimeMillis" value="60000"/>        
    </bean>   


    <tx:annotation-driven mode="aspectj" transaction-manager="transactionManager"/>
    <bean id="sessionFactory" class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</prop>
                <prop key="hibernate.query.substitutions">true 'Y', false 'N'</prop>
                <prop key="hibernate.jdbc.batch_size">15</prop>   
                <prop key="hibernate.connection.isolation">2</prop>
            </props>       
        </property>
         <property name="packagesToScan">
            <list>
                <value>com.jmt.model</value>
                <value>com.jmt.hibernate.dao</value>
            </list>
        </property>        
    </bean>
    <bean id="userDao" class="com.jmt.hibernate.dao.UserDaoImpl">
        <constructor-arg value="com.jmt.hibernate.dao.UserDaoImpl"/>
        <property name="sessionFactory" ref="sessionFactory"/>
    </bean>

4. even added a filter into my web.xml hoping that would inject the session properly:

<filter>
        <filter-name>sessionLoadingFilter</filter-name>
        <filter-class>org.springframework.orm.hibernate3.support.OpenSessionInViewFilter</filter-class>
    </filter>  

I didn’t add in a manager yet, hoping that fewer layers would make SOMETHING work…

Any help/ideas would be much appreciated!

Answer 1

Yuck, I did not think about where the call to the dao was being made, and yes, that’s why there wasn’t an open session. Someone had used spring dwr to call the dao directly from a jsp file. Once I got rid of that and made the call from my Controller, the session was finally being instantiated properly. Thanks for the help, Japs!