HibernateDaoSupport

[caravan]

this is my UserDAO,

package org.innolab.entity;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.orm.hibernate3.support.Hiberna teDaoSupport;


public class UserDAO extends HibernateDaoSupport {
private static final Log log = LogFactory.getLog(UserDAO.class);


protected void initDao() {
//do nothing
}

public void save(User transientInstance) {
log.debug("saving User instance");
try {
getHibernateTemplate().save(transientInstance);
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}
}


and there is my 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="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">


<bean id="sessionFactory"
class="org.springframework.orm.hibernate3.LocalSes sionFactoryBean">
<property name="configLocation"
value="classpath:hibernate.cfg.xml">
</property>
</bean>
<bean id="UserDAO" class="org.innolab.entity.UserDAO">
<property name="sessionFactory">
<ref bean="sessionFactory" />
</property>
</bean>
</beans>

and I got null pointer exception when I use my UserDAO, could anybody help me ? I am newbie thanks

[kravicha]

Hi,

Can you attach the stack Trace of the error so that it would be easier to investigate and as well paste the code of your hibernate.cfg.xml file.

Kartik

[caravan]

this is my hibernate.cfg.xml
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<!-- Generated by MyEclipse Hibernate Tools. -->
<hibernate-configuration>

<session-factory>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<property name="connection.url">jdbc:mysql://222.18.63.38:3306/innolab</property>
<property name="connection.username">root</property>
<property name="connection.driver_class">com.mysql.jdbc.Driv er</property>
<property name="myeclipse.connection.profile">com.mysql.jdbc .Driver</property>

<mapping resource="org/innolab/entity/User.hbm.xml"/>
</session-factory>
</hibernate-configuration>



and this is stack

java.lang.NullPointerException
org.innolab.action.LoginAction.execute(LoginAction .java:36)
org.apache.struts.chain.commands.servlet.ExecuteAc tion.execute(ExecuteAction.java:58)
org.apache.struts.chain.commands.AbstractExecuteAc tion.execute(AbstractExecuteAction.java:67)
org.apache.struts.chain.commands.ActionCommandBase .execute(ActionCommandBase.java:51)
org.apache.commons.chain.impl.ChainBase.execute(Ch ainBase.java:190)
org.apache.commons.chain.generic.LookupCommand.exe cute(LookupCommand.java:304)
org.apache.commons.chain.impl.ChainBase.execute(Ch ainBase.java:190)
org.apache.struts.chain.ComposableRequestProcessor .process(ComposableRequestProcessor.java:283)
org.apache.struts.action.ActionServlet.process(Act ionServlet.java:1913)
org.apache.struts.action.ActionServlet.doGet(Actio nServlet.java:449)
javax.servlet.http.HttpServlet.service(HttpServlet .java:617)
javax.servlet.http.HttpServlet.service(HttpServlet .java:717)

and this is my login action


@Override
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
UserDAO userDAO = new UserDAO();
userDAO.save(new User("10","10"));
return mapping.findForward("result");
}


thanks

[Marten Deinum]

Use [ code][/code ] tags when posting code.

Yyou are creating a new instance in the Action yourself instead of using the one from the applicationContext.

@Override
public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {
UserDAO userDAO = new UserDAO();
userDAO.save(new User("10","10"));
return mapping.findForward("result");
}

Next to that is is not recommended to use HibernateDaoSupport or HibernateTemplate anymore, simply use the Sessionfactory. Another note your catch is pretty much useless you shouldn't catch the exception, finally also saving/updating without proper transactionmanagent isn't going to work, unless you are using MyISAM tables which don't support transactions.

public class UserDAO {
	private static final Log log = LogFactory.getLog(UserDAO.class);
	private SessionFactory sf;
	
	public void setSessionFactory(SessionFactory sf) {
		this.sf=sf;
	}

	public void save(User transientInstance) {
		log.debug("saving User instance");
		sf.getCurrentSession().save(transientInstance);
	}
}

[caravan]

thanks for the advice, but I've changed applicationContext.xml as followed

<?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:p="http://www.springframework.org/schema/p"
	xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd">


	<bean id="sessionFactory"
		class="org.springframework.orm.hibernate3.LocalSessionFactoryBean">
		<property name="configLocation"
			value="classpath:hibernate.cfg.xml">
		</property>
	</bean>
	<bean id="UserDAO" class="org.innolab.entity.UserDAO">
		<property name="sessionFactory">
			<ref bean="sessionFactory" />
		</property>
	</bean>

	<bean id="login" class="org.innolab.action.LoginAction">
		<property name="userDAO" >
			<ref bean="UserDAO"/>
		</property>
	</bean>
	</beans>

and here is my

package org.innolab.action;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;
import org.innolab.base.BaseAction;
import org.innolab.entity.User;
import org.innolab.entity.UserDAO;

public class LoginAction extends Action implements BaseAction {
	private UserDAO userDAO;

	@Override
	public ActionForward execute(ActionMapping mapping, ActionForm form,
			HttpServletRequest request, HttpServletResponse response)
			throws Exception {
		userDAO.save(new User("10", "10"));
		return mapping.findForward("result");
	}

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

}

it's still giving me the null point exception...thanks

java.lang.NullPointerException
	org.innolab.action.LoginAction.execute(LoginAction.java:22)
	org.apache.struts.chain.commands.servlet.ExecuteAction.execute(ExecuteAction.java:58)
	org.apache.struts.chain.commands.AbstractExecuteAction.execute(AbstractExecuteAction.java:67)
	org.apache.struts.chain.commands.ActionCommandBase.execute(ActionCommandBase.java:51)
	org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
	org.apache.commons.chain.generic.LookupCommand.execute(LookupCommand.java:304)
	org.apache.commons.chain.impl.ChainBase.execute(ChainBase.java:190)
	org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:283)
	org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
	org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:449)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:617)
	javax.servlet.http.HttpServlet.service(HttpServlet.java:717)

[Marten Deinum]

Actions aren't managed by spring they are managed by struts, I suggest the spring reference guide, especially the struts integration part.

[caravan]

thanks for the advice I will read that part of it...

[caravan]

I've solved my proble, I've add a new line to my struts-config.xml

<controller>
		<set-property property="processorClass"
			value="org.springframework.web.struts.DelegatingRequestProcessor" />
	</controller>

and I've changed my applicationContext.xml to

<bean name="/login" class="org.innolab.action.LoginAction">
		<property name="userDAO" >
			<ref bean="UserDAO"/>
		</property>
	</bean>