无法投放DAO类

Question

I've CourseDetailsDAO and BeanDAO. I'm getting

university.BeanDAO cannot be cast to university.CourseDetailsDAO
    at CourseDetailsBean.performLookup(CourseDetailsBean.java:49)
    at CourseDetailsBean.CoursedetailsAction(CourseDetailsBean.java:38) 

those lines are :

CourseDetailsBean.java:49
CourseDetailsDAO helper = (CourseDetailsDAO) apc.getBean("courseDetailsDao");

and

CourseDetailsBean.java:38
performLookup(cID, cName, cDuration, cEligibility, cFee);

BeanDAO

public List getStudent() {
List<Student> students = null;
    try
        {
            Session session = sessionFactory.openSession();
            org.hibernate.Transaction tx = session.beginTransaction();
            Query q = session.createQuery("from university.Student");
            students = (List<Student>)q.list();  

CourseDetailsDAO

public List getcourseByName(String courseName) {
    List<Coursedetails> courselist = null;
    try
    {
        Session session = sessionFactory.openSession();
        org.hibernate.Transaction tx = session.beginTransaction();
        Criteria criteria = session.createCriteria(Coursedetails.class)
                .add(Restrictions.eq("coursename", courseName));
        courselist = (List<Coursedetails>) criteria.list();
        tx.commit();

but I noticed that server has few warnings and may those are predictions of failure.

 Warning: Could not register destruction callback [org.springframework.beans.factory.support.DisposableBeanAdapter@140f0e8] for attribute 'bean' because FacesRequestAttributes does not support such callbacks`
 Warning: Could not register destruction callback [org.springframework.beans.factory.support.DisposableBeanAdapter@13f8471] for attribute 'courseDetailsBean' because FacesRequestAttributes does not support such callbacks
 Warning: Could not register destruction callback [org.springframework.beans.factory.support.DisposableBeanAdapter@ce983a] for attribute 'bean' because FacesRequestAttributes does not support such callbacks
 Warning: Could not register destruction callback [org.springframework.beans.factory.support.DisposableBeanAdapter@16bafa6] for attribute 'courseDetailsBean' because FacesRequestAttributes does not support such callbacks

Answer 1

Check your spring bean configuration file,have you declared BeanDao and CourseDetailsDao as beans by assessing id's are proper or not. which you have used for getting the object references.

CourseDetailsDAO helper = (CourseDetailsDAO) apc.getBean("courseDetailsDao");