Question

我想从hibernate框架的mysql数据库中获取记录。为了实现这一点，我写了下面的代码。

List addresses = session.createQuery("Select P.address,P.personal_email,P.contact FROM PermanentAddress P,Employee E WHERE E.login_account='"+inf.getlogin_account()+"' AND E.employee_no=P.empno").list(); 
for (Iterator iterator = addresses.iterator(); iterator.hasNext();){ 
    PermanentAddress pa= (PermanentAddress) iterator.next(); 
    ad.setpaddr(pa.getaddress()); 
    ad.setpemail(pa.getpersonal_email()); 
    ad.setpcontact(pa.getcontact()); 
    System.out.println(ad.getpemail()); 
} 

，当我跑这个代码我得到下面的错误

javax.servlet.ServletException: java.lang.ClassCastException: [Ljava.lang.Object; cannot be cast to com.lms.model.PermanentAddress 
org.apache.struts.action.RequestProcessor.processException(RequestProcessor.java:545) 
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:486) 
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:274) 
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482) 
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:641) 
javax.servlet.http.HttpServlet.service(HttpServlet.java:722) 

请给我带路。

Answer 1

在您的查询中，您从PermanentAddress返回字段列表（P.address,P.personal_email,P.contact），而不是整个实体。试试这样：

List addresses = session.createQuery("Select P FROM PermanentAddress P,Employee E WHERE E.login_account = '" + inf.getlogin_account() + "' AND E.employee_no=P.empno").list();