spring - applicationContext.xml with datasource or hibernate.cfg.xml. Difference?

Question

Want to clear some confusion. I have applicationContext.xml.

Question 1: Whats the difference between 1 & 2. Are they both same with different approach?

Question 2:

I asked question on Spring forum regarding some problem. Onething he mentioned about pooling is below

if you need/want to use the internal connection pooling for hibernate I would advice against it and simply configure a datasource which supports connection pooling and inject that into your sessionfactorybean.

internal connection pooling for hibernate = This is number 2 below. Right?

simply configure a datasource which supports connection pooling and inject that into your sessionfactorybean = This is number 1 below. right?

1# -

<bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
        <property name="driverClassName" value="${jdbc.driverClassName}"/>
        <property name="url" value="${jdbc.url}"/>
        <property name="username" value="${jdbc.username}"/>
        <property name="password" value="${jdbc.password}"/>
        <property name="maxActive" value="100"/>
        <property name="maxIdle" value="30"/>
        <property name="maxWait" value="16000"/>
        <property name="minIdle" value="0"/>
    </bean>

 <!-- Hibernate SessionFactory -->
    <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="annotatedClasses">
            <list>
                <value>com.mkyong.customer.model.Customer</value>
            </list>
        </property>
        <property name="hibernateProperties">
            <props>
                <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</prop>
                <prop key="hibernate.show_sql">true</prop>
                <prop key="hibernate.format_sql">false</prop>
                <prop key="hibernate.generate_statistics">true</prop>
            </props>
        </property>
    </bean>

2# -

Pooling and connection info is in hibernate.cfg.xml

<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
        <property name="configLocation" value="classpath:hibernate.cfg.xml" />
    </bean>

Answer 1

Answer 1:

Both approaches are the same. By default , hibernate reads the configuration from classpath:hibernate.cfg.xml to build SessionFactory . LocalSessionFactoryBean just allows you to setup hibernate configuration inside applicationContext.xml instead of hibernate.cfg.xml .

If a same property is specified in both files , depending on the property , it will has addictive effect or the properties specified in applicationContext.xml will take higher priority such that those values in hibernate.cfg.xml will be ignored.

For method 1, annotatedClasses and hibernateProperties should have the addictive effect with the corresponding values in hibernate.cfg.xml . The DBCP dataSouruce in applicationContext.xml should cause the related properties in hibernate.cfg.xml being ignored.

Answer 2:

For method 2 , if you don't specify any properties of LocalSessionFactoryBean , all the hibernate configurations are specified by the hibernate.cfg.xml. If there are no connection pool configured in hibernate.cfg.xml , hibernate's own connection pooling algorithm is used by default , which is quite rudimentary and not intended for use in a production system, or even for performance testing.