急 考试中 这个sessionFactory老是为NULL

 <context:annotation-config/>
	 <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
	 	<property name="driverClassName">
	 		<value>oracle.jdbc.driver.OracleDriver</value>
	 	</property>
	 	<property name="url">
	 		<value>jdbc:oracle:thin:@localhost:1521:orcl</value>
	 	</property>
	 	<property name="username">
	 		<value>scott</value>
	 	</property>
	 	<property name="password">
	 		<value>admin</value>
	 	</property>
	 </bean>
	 <bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
	 	<property name="dataSource">
	 		<ref bean="dataSource"/>
	 	</property>
	 	 <property name="hibernateProperties">
	        <props>
	     		<prop key="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</prop>
	     		<prop key="hibernate.show_sql">true</prop>
	        </props>
	     </property>
	     <property name="packagesToScan">
				<value>com.entity</value>
			</property>
	 </bean>