org.hibernate.HibernateException: Could not obtain transaction-synchronized Session for current thread

<bean id="userDAO" class="com.my.portal.user.UserDAOImpl">
    <property name="sessionFactory" ref="sessionFactory"/>
</bean>

<context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>/WEB-INF/spring/*.xml</param-value>
</context-param>

<!-- Creates the Spring Container shared by all Servlets and Filters -->
<listener>
    <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class>
</listener>

<!-- Processes application requests -->
<servlet>
    <servlet-name>appServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>WEB-INF/spring/servlet-context.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>appServlet</servlet-name>
    <url-pattern>/</url-pattern>
</servlet-mapping>

<!-- Data Source Setup -->
<bean id="myDS" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
    <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
    <property name="url" value="jdbc:mysql://localhost:3306/mydb"/>
    <property name="username" value="root"/>
    <property name="password" value=""/>
    <property name="maxIdle" value="5"/>
    <property name="maxActive" value="10"/>
</bean>

<!-- Hibernate Sessionfactory Bean Definition -->
<bean id="sessionFactory" class="org.springframework.orm.hibernate4.LocalSessionFactoryBean">
    <property name="dataSource" ref="myDS"/>
    <property name="annotatedClasses">
        <list>
            <value>com.my.portal.user.User</value>
        </list>
    </property>
    <property name="hibernateProperties">
        <props>
            <prop key="hibernate.dialect">org.hibernate.dialect.MySQL5InnoDBDialect</prop>
            <prop key="hibernate.show_sql">true</prop>
        </props>
    </property>
</bean>

<!-- Hibernate Transaction Setup -->
<bean id="transactionManager" class="org.springframework.orm.hibernate4.HibernateTransactionManager">
    <property name="sessionFactory" ref="sessionFactory"/>
</bean>

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

@Entity

@Id
@Column(name="UserId")
@GeneratedValue(strategy=GenerationType.IDENTITY)
private int UserId;
private String FirstName;
private String LastName;
public int getUserId() {
    return UserId;
}
public void setUserId(int userId) {
    UserId = userId;
}
public String getFirstName() {
    return FirstName;
}
public void setFirstName(String firstName) {
    FirstName = firstName;
}
public String getLastName() {
    return LastName;
}
public void setLastName(String lastName) {
    LastName = lastName;
}
@Override
public String toString(){
    return "UserId="+UserId+", FirstName="+FirstName+", LastName="+LastName;
}

@Controller

private static final Logger logger = LoggerFactory.getLogger(UserController.class);

private UserService userService;

@Autowired
public UserController(UserService userService){
    this.userService = userService;
}

@RequestMapping(value = "/user", method = RequestMethod.GET)
public String user(Locale locale, Model model){
    model.addAttribute("getUser",userService.getUser());
    return "user";

}

@Repository

public List<User> getUser();

private static final Logger logger = LoggerFactory.getLogger(UserDAOImpl.class);

private SessionFactory sessionFactory;

@Autowired
public void setSessionFactory(SessionFactory sessionFactory){
    this.sessionFactory = sessionFactory;
}

private Session currentSession() {
    return sessionFactory.getCurrentSession();
}

@SuppressWarnings("unchecked")
@Override
public List<User> getUser() {
    List<User> userList = currentSession().createQuery("from User").list();
    return userList;
}

@Service

public String getMessage();

@Service

private UserDAO userDAO;

@Autowired
public void setUserDAO(UserDAO userDAO) {
    this.userDAO = userDAO;
}

public String getMessage(){
    return "User Registration Page";
}

@SuppressWarnings("unchecked")
@Override
@Transactional
public List<User> getUser(){
    logger.info("getUser()");
    return this.userDAO.getUser();
}