Estou enfrentando um problema para conectar o gerenciador de entidades com o bean presente no contexto do aplicativo. sempre que eu faço alguma operação, dá NullPointerException.

este é meu arquivo applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-3.0.xsd">

    <context:component-scan base-package="com.ajit.retail"/>

    <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="org.postgresql.Driver"/>
        <property name="url" value="jdbc:postgresql://localhost/retail"/>
        <property name="username" value="retail_user"/>
        <property name="password" value="password"/>
    </bean>

    <bean id="entityManagerOne" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
        <property name="dataSource" ref="dataSource"/>
        <property name="jpaVendorAdapter">
            <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
                <property name="showSql" value="true"/>
                <property name="databasePlatform" value="org.hibernate.dialect.PostgreSQL82Dialect"/>
            </bean>
        </property>
    </bean>

    <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
        <property name="entityManagerFactory" ref="entityManagerOne"/>
    </bean>

    <tx:annotation-driven transaction-manager="transactionManager"/>

    </beans>

este é o arquivo java em que estou criando o gerenciador de entidades

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

public class AbstractRepository {

    @PersistenceContext
    EntityManager entityManager;
}

então sempre que eu uso este gerenciador de entidades, ele dá exceção de ponteiro nulo, por favor, ajude!