a lazyInitalizationException problem

[crazysheep]

I am trying to use the Struts ,Hibernate and Spring framework in a webapp.I have added the OpenSessenInViewFilter in the web.xml.There is a problem occured.After the user logged on to the system (A User object saved in the session scope) there is a welcome page and in this page I used user.getKnowledges().size() method,then a lazyInitalizationException occured.
Here is a part of the error message:

Servlet.service() for servlet jsp threw exception
org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: com.lab1000.project.pojo.Member.knowledges - no session or session was closed
at org.hibernate.collection.AbstractPersistentCollect ion.throwLazyInitializationException(AbstractPersi stentCollection.java:191)
at org.hibernate.collection.AbstractPersistentCollect ion.initialize(AbstractPersistentCollection.java:1 83)
at org.hibernate.collection.AbstractPersistentCollect ion.read(AbstractPersistentCollection.java:48)
at org.hibernate.collection.PersistentSet.size(Persis tentSet.java:110)
at org.apache.jsp.admin.welcome_jsp._jspService(welco me_jsp.java:93)
at org.apache.jasper.runtime.HttpJspBase.service(Http JspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:803)
at org.apache.jasper.servlet.JspServletWrapper.servic e(JspServletWrapper.java:393)
at org.apache.jasper.servlet.JspServlet.serviceJspFil e(JspServlet.java:320)
at org.apache.jasper.servlet.JspServlet.service(JspSe rvlet.java:266)
at javax.servlet.http.HttpServlet.service(HttpServlet .java:803)

After asking my classmate ,I haved created a class inherited the org.springframework.orm.hibernate3.support.OpenSes sionInViewFilter class and overrided the getSession() method ,before return the session,I haved setted the session.flushMode to be Hibernate.AUTO.
But the lazyInitalizationException still coccured.

[crazysheep]

Is there something i did not make explicit? Why is there no reply for my question?Someone can help me? I am a chinese college student and I will be very happy to make friends with college student from other countries.

[techfoundry]

The OpenSessionInViewFilter closes the session (associated with the thread handling the HTTP request) at the end of each HTTP request AFAIK (based upon the behaviour of OpenEntityManagerInViewInterceptor which does the same when using JPA and I assume a Hibernate session is equivalent to a EntityManager here).

A session object has a longer lifetime than a single HTTP request, so when the session is closed at the end of the HTTP request in which the session object was created, you will not be able to fetch any lazy fields in the session object without a lazy initialization exception occurring.

Solutions to this design problem are -

1. Eagerly fetch all fields of the object to be stored in the session in the HTTP request that fetches the object from the database.

2. Don't store the object in the session, store an identifier for the object and fetch the object from the database using the identifier when it's required.

3. Erm, can't think of a third solution

Andy.

[al0]

Why, 3rd solution is to reattach (or merge) this object.

The OpenSessionInViewFilter closes the session (associated with the thread handling the HTTP request) at the end of each HTTP request AFAIK (based upon the behaviour of OpenEntityManagerInViewInterceptor which does the same when using JPA and I assume a Hibernate session is equivalent to a EntityManager here).

A session object has a longer lifetime than a single HTTP request, so when the session is closed at the end of the HTTP request in which the session object was created, you will not be able to fetch any lazy fields in the session object without a lazy initialization exception occurring.

Solutions to this design problem are -

1. Eagerly fetch all fields of the object to be stored in the session in the HTTP request that fetches the object from the database.

2. Don't store the object in the session, store an identifier for the object and fetch the object from the database using the identifier when it's required.

3. Erm, can't think of a third solution

Andy.

[prince5140]

I had the same issue but I resolved it. It was a configuration problem. Can you attach your configuration files.

[crazysheep]

Thanks for your help.
And dear prince1540 here is my web.xml configuration file:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4" xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>/WEB-INF/classes/system.xml,/WEB-INF/classes/beans.xml</param-value>
</context-param>

<servlet>
<servlet-name>SpringContextServlet</servlet-name>
<servlet-class>
org.springframework.web.context.ContextLoaderServl et
</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>

<servlet>
<servlet-name>action</servlet-name>
<servlet-class>org.apache.struts.action.ActionServlet</servlet-class>
<init-param>
<param-name>config</param-name>
<param-value>/WEB-INF/struts-config.xml</param-value>
</init-param>
<init-param>
<param-name>debug</param-name>
<param-value>3</param-value>
</init-param>
<init-param>
<param-name>detail</param-name>
<param-value>3</param-value>
</init-param>
<load-on-startup>0</load-on-startup>
</servlet>

<servlet-mapping>
<servlet-name>action</servlet-name>
<url-pattern>*.html</url-pattern>
</servlet-mapping>

<filter>
<filter-name>hibernateFilter</filter-name>
<filter-class>
org.springframework.orm.hibernate3.support.OpenSes sionInViewFilter
</filter-class>
<init-param>
<param-name>singleSession</param-name>
<param-value>true</param-value>
</init-param>
</filter>

<filter>
<filter-name>Set Character Encoding</filter-name>
<filter-class>com.lab1000.project.system.CharsetEncodingFi lter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>GB2312</param-value>
</init-param>
</filter>

<filter-mapping>
<filter-name>Set Character Encoding</filter-name>
<servlet-name>action</servlet-name>
</filter-mapping>

<filter-mapping>
<filter-name>hibernateFilter</filter-name>
<url-pattern>*.html</url-pattern>
</filter-mapping>

<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>

[prince5140]

Hello crazysheep,

can you attach system.xml and beans.xml

Thanks

[crazysheep]

Oh sorry.Here are my spring configuration files:

system.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>

<bean id="classficationDao"
class="com.lab1000.project.dao.impl.ClassficationD aoImpl" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="classficationDaoProxy"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
abstract="false" >
<property name="target" ref="classficationDao" />
<property name="transactionManager" ref="txm" />
<property name="proxyTargetClass" value="true"/>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save">PROPAGATION_REQUIRED</prop>
<prop key="update">PROPAGATION_REQUIRED</prop>
<prop key="delete">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="newsDao" class="com.lab1000.project.dao.impl.NewsDaoImpl" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="newsDaoProxy"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
abstract="false" >
<property name="target" ref="newsDao" />
<property name="transactionManager" ref="txm" />
<property name="proxyTargetClass" value="true"/>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save">PROPAGATION_REQUIRED</prop>
<prop key="update">PROPAGATION_REQUIRED</prop>
<prop key="delete">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="knowledgeDao"
class="com.lab1000.project.dao.impl.KnowledgeDaoIm pl" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="knowledgeDaoProxy"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
abstract="false" lazy-init="default" autowire="default"
dependency-check="default">
<property name="target">
<ref bean="knowledgeDao" />
</property>
<property name="transactionManager">
<ref bean="txm" />
</property>
<property name="proxyTargetClass">
<value>true</value>
</property>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save">PROPAGATION_REQUIRED</prop>
<prop key="delete">PROPAGATION_REQUIRED</prop>
<prop key="update">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="memberDao"
class="com.lab1000.project.dao.impl.MemberDaoImpl" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="memberDaoProxy"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
abstract="false" >
<property name="target" ref="memberDao" />
<property name="transactionManager" ref="txm" />
<property name="proxyTargetClass" value="true"/>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save">PROPAGATION_REQUIRED</prop>
<prop key="update">PROPAGATION_REQUIRED</prop>
<prop key="delete">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="questionDao"
class="com.lab1000.project.dao.impl.QuestionDaoImp l" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="productDao"
class="com.lab1000.project.dao.impl.ProductDaoImpl " abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

</beans>

beans.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>

<bean id="classficationDao"
class="com.lab1000.project.dao.impl.ClassficationD aoImpl" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="classficationDaoProxy"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
abstract="false" >
<property name="target" ref="classficationDao" />
<property name="transactionManager" ref="txm" />
<property name="proxyTargetClass" value="true"/>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save">PROPAGATION_REQUIRED</prop>
<prop key="update">PROPAGATION_REQUIRED</prop>
<prop key="delete">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="newsDao" class="com.lab1000.project.dao.impl.NewsDaoImpl" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="newsDaoProxy"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
abstract="false" >
<property name="target" ref="newsDao" />
<property name="transactionManager" ref="txm" />
<property name="proxyTargetClass" value="true"/>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save">PROPAGATION_REQUIRED</prop>
<prop key="update">PROPAGATION_REQUIRED</prop>
<prop key="delete">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="knowledgeDao"
class="com.lab1000.project.dao.impl.KnowledgeDaoIm pl" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="knowledgeDaoProxy"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
abstract="false" lazy-init="default" autowire="default"
dependency-check="default">
<property name="target">
<ref bean="knowledgeDao" />
</property>
<property name="transactionManager">
<ref bean="txm" />
</property>
<property name="proxyTargetClass">
<value>true</value>
</property>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save">PROPAGATION_REQUIRED</prop>
<prop key="delete">PROPAGATION_REQUIRED</prop>
<prop key="update">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="memberDao"
class="com.lab1000.project.dao.impl.MemberDaoImpl" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="memberDaoProxy"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
abstract="false" >
<property name="target" ref="memberDao" />
<property name="transactionManager" ref="txm" />
<property name="proxyTargetClass" value="true"/>
<property name="transactionAttributes">
<props>
<prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
<prop key="save">PROPAGATION_REQUIRED</prop>
<prop key="update">PROPAGATION_REQUIRED</prop>
<prop key="delete">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="questionDao"
class="com.lab1000.project.dao.impl.QuestionDaoImp l" abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

<bean id="productDao"
class="com.lab1000.project.dao.impl.ProductDaoImpl " abstract="false">
<property name="sessionFactory" ref="sessionFactory" />
</bean>

</beans>

Here is the connectionConfig.properties

connectionConfig.user=root
connectionConfig.password=007
connectionConfig.driver=com.mysql.jdbc.Driver
connectionConfig.url=jdbc:mysql://localhost/labdb

Here productDaoImpl,newsDaoImpl and the questionDaoImpl are not completed ,so there are no their transactionManagerProxy classes.

[prince5140]

So do you any business layer or you are calling daos directly from struts actions. beans.xml and system.xml looks identical? Also you dont have to define transaction proxy each and everytime. Please look below:


<bean id="abstractTxDefinition"
class="org.springframework.transaction.interceptor .TransactionProxyFactoryBean"
lazy-init="true">
<property name="transactionManager">
<ref local="mdmTransactionManager" />
</property>
<property name="transactionAttributes">
<props>
<prop key="*">PROPAGATION_REQUIRED</prop>
</props>
</property>
</bean>

<bean id="sampleService1" parent="abstractTxDefinition">
<property name="target">
<ref bean="sampleService1Target" />
</property>
</bean>

<bean id="sampleService2" parent="abstractTxDefinition">
<property name="target">
<ref bean="sampleService2Target" />
</property>
</bean>