LazyInitializationException: could not initialize proxy - no Session

SpringMVC4+JPA+Hibernate4，设置fetch = FetchType.LAZY后，
报错：org.hibernate.LazyInitializationException: could not initialize proxy - no Session

我不想设置为 fetch = FetchType.EAGER，如何设置fetch = FetchType.LAZY，成功加载所需要的数据？

配置文件如下：

web.xml
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<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">

<display-name>Web Application</display-name>

<filter>
<filter-name>CharacterEncodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>CharacterEncodingFilter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>

<servlet>
<servlet-name>zanwo</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>zanwo</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

<welcome-file-list>
<welcome-file>index.html</welcome-file>
</welcome-file-list>
</web-app>
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spring-servlet.xml
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<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:p="http://www.springframework.org/schema/p" xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:context="http://www.springframework.org/schema/context"
xmlns:util="http://www.springframework.org/schema/util" 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 
            http://www.springframework.org/schema/mvc
            http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd             
            http://www.springframework.org/schema/util
            http://www.springframework.org/schema/util/spring-util-3.0.xsd
            http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx.xsd">

<!-- active @Controller mode -->
<mvc:annotation-driven />

<mvc:default-servlet-handler />

<mvc:resources mapping="/images/**" location="/images/" />
<mvc:resources mapping="/js/**" location="/js/"/>

<context:annotation-config />

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

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

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

<bean class="org.springframework.web.servlet.mvc.annotation.AnnotationMethodHandlerAdapter"/>

<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="persistenceUnitName" value="myPU" />
<property name="persistenceXmlLocation" value="classpath:META-INF/persistence.xml"></property>
</bean>

<bean id="messageSource" class="org.springframework.context.support.ReloadableResourceBundleMessageSource">
<property name="basename" value="classpath:i18n/messages" />
<property name="defaultEncoding" value="UTF-8" />
</bean>

<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"> 
        <property name="maxUploadSize" value="800000"/> 
    </bean>

<bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<property name="exceptionMappings">
<props>
<prop key="org.springframework.web.multipart.MaxUploadSizeExceededException">error</prop>
</props>
</property>
</bean>

<bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
<property name="prefix">
<value>/WEB-INF/pages/</value>
</property>
<property name="suffix">
<value>.jsp</value>
</property>
</bean>
</beans>
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persistence.xml
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<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_1_0.xsd"
version="1.0">
<persistence-unit name="myPU" transaction-type="RESOURCE_LOCAL">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<properties>
<property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver" />
<property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/mysql" />
<property name="hibernate.connection.username" value="root" />
<property name="hibernate.connection.password" value="root" />
<property name="hibernate.show_sql" value="true" />
<property name="hibernate.format_sql" value="false" />
<property name="hibernate.hbm2ddl.auto" value="update" />
</properties>
</persistence-unit>
</persistence>
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其中两个类，shop（店铺）和商品（product）是一对多关系，我是这样定义：
Product.java
@Entity
@Table(name = "product")
public class Product extends BaseEntity implements Serializable {

private static final long serialVersionUID = 4386742079736072275L;

@Id
@GeneratedValue
@Column(name = "prod_id")
private Long prodId;

@ManyToOne(cascade = { CascadeType.ALL }, fetch = FetchType.LAZY, optional = false)
@JoinColumn(name = "shop_id")
private Shop shop;

@Column(name = "prod_name")
private String prodName;

@Column(name = "prod_desc")
private String prodDesc;
   
getter() and setter().....
}


Shop.java
@Entity
@Table(name = "shop")
public class Shop extends BaseEntity implements Serializable {
private static final long serialVersionUID = 2949762130923624926L;
@Id
@GeneratedValue
@Column(name = "shop_id")
private Long shopId;

@Column(name = "shop_name")
private String shopName;

@Column(name = "shop_desc")
private String shopDesc;

@OneToMany(cascade = { CascadeType.ALL }, fetch = FetchType.LAZY, mappedBy = "shop")
private Set<Product> products = new HashSet<Product>(0);

getter() and setter().....

}

当页面访问${product.shop.shopName}就会报错：org.hibernate.LazyInitializationException: could not initialize proxy - no Session