第一次在csdn问问题。myecplise8.5+struts1.3+hibernate3.3开发，不能插入数据到mysql5.1，出现这个问题。为什么呢？

Question

javax.servlet.ServletException: could not load an entity: [cup.edu.hibernate.Dept#1]
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:286)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
起 因org.hibernate.exception.JDBCConnectionException: could not load an entity: [cup.edu.hibernate.Dept#1]
org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:97)
org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:66)
org.hibernate.loader.Loader.loadEntity(Loader.java:1899)
org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:71)
org.hibernate.loader.entity.AbstractEntityLoader.load(AbstractEntityLoader.java:65)
org.hibernate.persister.entity.AbstractEntityPersister.load(AbstractEntityPersister.java:3062)
org.hibernate.event.def.DefaultLoadEventListener.loadFromDatasource(DefaultLoadEventListener.java:434)
org.hibernate.event.def.DefaultLoadEventListener.doLoad(DefaultLoadEventListener.java:415)
org.hibernate.event.def.DefaultLoadEventListener.load(DefaultLoadEventListener.java:165)
org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:223)
org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:126)
org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:906)
org.hibernate.impl.SessionImpl.get(SessionImpl.java:843)
cup.edu.hibernate.DeptDAO.findById(DeptDAO.java:54)
cup.edu.struts.action.AddstuffAction.execute(AddstuffAction.java:59)
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.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

Answer 1

could not load an entity  无法读取实体对象如果没有猜错的话，是你的配置文件有错或者是实体对象没有映射

Answer 2

javax.servlet.ServletException: a different object with the same identifier value was already associated with the session: [cup.edu.hibernate.Stuff#44]
org.apache.struts.chain.ComposableRequestProcessor.process(ComposableRequestProcessor.java:286)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1913)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
起 因org.hibernate.NonUniqueObjectException: a different object with the same identifier value was already associated with the session: [cup.edu.hibernate.Stuff#44]
org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:191)
org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:144)
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:56)
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:50)
org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
org.hibernate.impl.SessionImpl.fireSave(SessionImpl.java:563)
org.hibernate.impl.SessionImpl.save(SessionImpl.java:551)
org.hibernate.impl.SessionImpl.save(SessionImpl.java:547)
cup.edu.hibernate.StuffDAO.save(StuffDAO.java:42)
cup.edu.struts.action.AddstuffAction.execute(AddstuffAction.java:66)
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.doPost(ActionServlet.java:462)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

Answer 3

StuffDAO stuffDAO=new StuffDAO();
Stuff stuff=new Stuff();
stuff.setStuffid(addstuffForm.getStuffid());
stuff.setStuffname(addstuffForm.getStuffname());
stuff.setSex(addstuffForm.getSex());
stuff.setAge(addstuffForm.getAge());
stuff.setIdcard(addstuffForm.getIdcard());
stuff.setWage(addstuffForm.getWage());
stuff.setSocialsecurity(addstuffForm.getSocialsecurity());
stuff.setEducation(addstuffForm.getEducation());
stuff.setDegree(addstuffForm.getDegree());
stuff.setTechgrade(addstuffForm.getTechgrade());
System.out.println("addstuff---------->1");
DeptDAO deptDAO=new DeptDAO();
Dept dept=new Dept();
dept=deptDAO.findById(addstuffForm.getDeptid());
stuff.setDept(dept);

stuff.setPosition(addstuffForm.getPosition());
stuff.setTitle(addstuffForm.getTitle());
stuff.setStatus(addstuffForm.getStatus());
stuffDAO.save(stuff);

Answer 4

配置是照着一个示例配的，不清楚有没有问题。第一次插数据，程序走了一遍，但是数据库里没插成功。
第二次action，出现这个提示：
javax.servlet.ServletException: a different object with the same identifier value was already associated with the session: [cup.edu.hibernate.Stuff#44]
应该指已经有了相同的数据吧。hibernate已经有数据了，但是没插到mysql里吧，这是为什么呢

Answer 5

(StuffDAO.java:42)是哪行？
你 这Dept dept=new Dept();不要new 试试Dept dept=deptDAO.findById(addstuffForm.getDeptid());

Answer 6

public void save(Stuff transientInstance) {
log.debug("saving Stuff instance");
try {
getSession().save(transientInstance);//42行
log.debug("save successful");
} catch (RuntimeException re) {
log.error("save failed", re);
throw re;
}
}
应该是getSession()的问题，getSession()会出现什么问题呢？
/hr/src/cup/edu/hibernate/IBaseHibernateDAO.javapackage cup.edu.hibernate;import org.hibernate.Session;
/**
 * Data access interface for domain model
 * @author MyEclipse Persistence Tools
 */
public interface IBaseHibernateDAO {
public Session getSession();
}

Answer 7

/hr/src/cup/edu/hibernate/BaseHibernateDAO.javapackage cup.edu.hibernate;import org.hibernate.Session;
/**
 * Data access object (DAO) for domain model
 * @author MyEclipse Persistence Tools
 */
public class BaseHibernateDAO implements IBaseHibernateDAO {

public Session getSession() {
return HibernateSessionFactory.getSession();
}

}*******************************************************************
/hr/src/cup/edu/hibernate/HibernateSessionFactory.java    public static Session getSession() throws HibernateException {
        Session session = (Session) threadLocal.get(); if (session == null || !session.isOpen()) {
if (sessionFactory == null) {
rebuildSessionFactory();
}
session = (sessionFactory != null) ? sessionFactory.openSession()
: null;
threadLocal.set(session);
}        return session;
    }
最后getSession（）应该是在这里

Answer 8

你这个出现了往同一张表中插入相同主键的PO，没有看你完整的代码，我觉得stuff.setStuffid(addstuffForm.getStuffid());这一句是不是把主键给放进新的Stuff对象中了？建议把这一句去掉试试，希望说的能帮上楼主，或者抛砖引玉。