无法强制转换java DAO类

Question

我学过tailsdao和BeanDAO。我要走了

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

这些线路是：

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

及

CourseDetailsBean。爪哇：38
performLookup(cID, cName, cDuration, cEligibility, cFee);

比恩多

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();  

Coursedateilsdao

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();

但我注意到服务器上几乎没有警告，这些可能是对故障的预测

 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

检查您的SpringBean配置文件，您是否通过评估id是否正确，将BeanDao和CourseDetailsDao声明为bean。用于获取对象引用的

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