Question

Hiii伙计们我正在构建一个简单的ToDoList（这只是我的项目的开始），它应该使用MAMP作为DB将任务添加到我的日程表中。我的问题是season.save（）缺少查询中的主键（“id”）; 我有以下代码：主要课程：

 package Model;


    import java.util.Date;
    import java.util.List;

    import org.hibernate.HibernateException;
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.cfg.AnnotationConfiguration;


    //create exception instead of HibernateException  ToDoListDAOException
    public class HibernateToDoListDAO implements IToDoListDAO {

        SessionFactory factory = null;
        private static final HibernateToDoListDAO _instanceDAO = new HibernateToDoListDAO();


        // no need to do connection or use driver to my sql
        private HibernateToDoListDAO(){
            factory = new AnnotationConfiguration().configure().buildSessionFactory();
        }

        public static HibernateToDoListDAO getInstance()
        {
            return _instanceDAO;
        }

        @Override
        public void addMemorandums(items memorandum) throws HibernateException {
            Session session = factory.openSession();
            try{
                session.beginTransaction();
                //create the query for memorandum members
                session.saveOrUpdate(memorandum);
                System.out.println("after save : user id's = "+memorandum.getId());

                session.getTransaction().commit();
            }catch(HibernateException e )
            {
                e.printStackTrace();
                if ( session.getTransaction() != null )
                    session.getTransaction().rollback();
            }finally{
                session.close();
            }
        }

        @Override
        public void updateMemorandums(items memorandum) throws HibernateException {
            Session session = null;
            try{
                session = factory.openSession();
                session.beginTransaction();
                session.update(memorandum);
                session.getTransaction().commit();
            }catch(HibernateException e )
            {
                e.printStackTrace();
                if ( session.getTransaction() != null )
                    session.getTransaction().rollback();
            }finally{
                session.close();
            }
        }

        @Override
        public void deleteMemorandums(items memorandum) throws HibernateException {
            Session session = null;
            try{
                session = factory.openSession();
                session.beginTransaction();
                session.delete(memorandum);
                session.getTransaction().commit();
            }catch(HibernateException e )
            {
                e.printStackTrace();
                if ( session.getTransaction() != null )
                    session.getTransaction().rollback();
            }finally{
                session.close();
            }
        }

        @SuppressWarnings("unchecked")
        @Override
        public List<items> getMemorandums() throws HibernateException {
            List<items> memorandum = null;
            Session session = null;
            try{
                session = factory.openSession();
                session.beginTransaction();
                memorandum = session.createQuery("from todolists").list();
            }catch(HibernateException e )
            {
                e.printStackTrace();
                if ( session.getTransaction() != null )
                    session.getTransaction().rollback();
            }finally{
                session.close();
            } 
            return memorandum;
        }

        public static void main(String[] args) {

            @SuppressWarnings("deprecation")
            String dateTask = "26/11/2016";
            items task1 = new items(2012,"football", dateTask , "ball");
            HibernateToDoListDAO.getInstance().addMemorandums(task1);

        }
    }

项目类：

package Model;

import java.util.Date;

public class items {

    private int id;// primary key that connect to the users
    private String taskname;
    private String date;
    private String note;


    public items(){
        taskname = "basketball";
        note = "a fun game";
        date = "15/10/2016";
        id = 2012;
    }

    public items(int id, String taskName, String taskDate, String note) {
        super();
        this.taskname = taskName;
        this.date = taskDate;
        this.note = note;
        this.id = id;
    }

    public String getTaskname() {
        return taskname;
    }

    public void setTaskname(String taskname) {
        this.taskname = taskname;
    }

    public String getDate() {
        return date;
    }

    public void setDate(String date) {
        this.date = date;
    }

    public String getNote() {
        return note;
    }

    public void setNote(String note) {
        this.note = note;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

}

我正在尝试运行这个简单的程序，我得到的例外情况如下：

（例外）

Hibernate: insert into items (taskname, date, note) values (?, ?, ?)
org.hibernate.HibernateException: The database returned no natively generated identity value
    at org.hibernate.id.IdentifierGeneratorHelper.getGeneratedIdentity(IdentifierGeneratorHelper.java:84)
    at org.hibernate.id.IdentityGenerator$GetGeneratedKeysDelegate.executeAndExtract(IdentityGenerator.java:98)
    at org.hibernate.id.insert.AbstractReturningDelegate.performInsert(AbstractReturningDelegate.java:57)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2329)
    at org.hibernate.persister.entity.AbstractEntityPersister.insert(AbstractEntityPersister.java:2836)
    at org.hibernate.action.EntityIdentityInsertAction.execute(EntityIdentityInsertAction.java:71)
    at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:267)
    at org.hibernate.event.def.AbstractSaveEventListener.performSaveOrReplicate(AbstractSaveEventListener.java:321)
    at org.hibernate.event.def.AbstractSaveEventListener.performSave(AbstractSaveEventListener.java:204)
    at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:130)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:210)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:195)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.performSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:117)
    at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:93)
    at org.hibernate.impl.SessionImpl.fireSaveOrUpdate(SessionImpl.java:677)
    at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:669)
    at org.hibernate.impl.SessionImpl.saveOrUpdate(SessionImpl.java:665)
    at Model.HibernateToDoListDAO.addMemorandums(HibernateToDoListDAO.java:36)
    at Model.HibernateToDoListDAO.main(HibernateToDoListDAO.java:111)

hibernate.cfg.xml中：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration SYSTEM 
"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

<hibernate-configuration>
   <session-factory>
   <property name="hibernate.dialect">
      org.hibernate.dialect.MySQLDialect
   </property>
   <property name="hibernate.connection.driver_class">
      com.mysql.jdbc.Driver
   </property>

   <!-- Assume test is the database name -->
   <property name="hibernate.connection.url">
      jdbc:mysql://localhost:3306/hit
   </property>
 <property name="hibernate.connection.username">hit</property>
 <property name="hibernate.connection.password">hit</property>
 <property name="show_sql">true</property>

 <!-- Mapping files -->
 <mapping resource="hibernate.mapping.xml"/>

</session-factory>
</hibernate-configuration>

hibernate.mapping.xml：

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC 
 "-//Hibernate/Hibernate Mapping DTD//EN"
 "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"> 

<hibernate-mapping>

   <!-- *********** items table   ******* -->
<!-- full class name including the packege name -->
   <class name="Model.items" table="items">
      <meta attribute="class-description">
         This class contains the the items details. 
      </meta>
      <id name="id" type="int" column="id"> <!-- primary key -->
         <generator class="native"/>
      </id>

      <property name="taskname" column="taskname" type="string"/>
      <property name="date" column="date" type="string"/>
      <property name="note" column="note" type="string"/>
   </class>

   <!-- *********** users table   ******* -->

   <!-- full class name including the packege name -->

   <class name="Model.users" table="users">
      <meta attribute="class-description">
         This class contains the users details. 
      </meta>
      <id name="id" type="int" column="id">
         <generator class="native"/>
      </id>
      <property name="name" column="name" type="string"/>
      <property name="age" column="age" type="int"/>
   </class>


</hibernate-mapping>

我正在使用mamp作为我的数据库（使用mysql）。问题是查询只插入三个而不是四个变量（缺少“id”成员）。有人可以帮我解决这个问题吗？

谢谢你们。

Answer 1

您必须自动增加表的标识列才能避免此错误。编写alter table查询以使标识列自动递增。这应该可以解决你的问题

Hibernate session.save（）缺少查询成员

1 个答案: