我是hibernate的新手，我有愚蠢的问题。我的档案：
的hibernate.cfg.xml
<?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.PostgreSQLDialect
</property>
<property name="hibernate.connection.driver_class">
org.postgresql.Driver
</property>
<!-- Assume test is the database name -->
<property name="hibernate.connection.url">
jdbc:postgresql://localhost/booktown
</property>
<property name="hibernate.connection.username">
mirek
</property>
<mapping resource="Books.hbm.xml"/>
</session-factory>
</hibernate-configuration>
books.hbm.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>
<class name="Books" table="books">
<meta attribute="Książki w booktown">
This class contains the employee detail.
</meta>
<id name="id" type="int" column="id">
<generator class="native"/>
</id>
<property name="title" column="title" type="string"/>
<property name="author_id" column="author_id" type="int"/>
<property name="subject_id" column="subject_id" type="int"/>
</class>
</hibernate-mapping>
Books.java
public class Books
{
private int id;
private String title;
private int author_id;
private int subject_id;
public Books(String title, int author_id, int subject_id)
{
this.title = title;
this.author_id = author_id;
this.subject_id = subject_id;
}
public void setId(int id)
{
this.id = id;
}
public void setTitle(String title)
{
this.title = title;
}
public void setAuthorId(int author_id)
{
this.author_id = author_id;
}
public void setSubjectId(int subject_id)
{
this.subject_id = subject_id;
}
public int getId()
{
return id;
}
public String getTitle()
{
return title;
}
public int getAuthorId()
{
return author_id;
}
public int getSubjectId()
{
return subject_id;
}
}
和Booktown.java
import java.util.Iterator;
import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
public class Booktown
{
private static SessionFactory factory;
private static ServiceRegistry serviceRegistry;
public static void main(String[] args)
{
try
{
//private static SessionFactory configureSessionFactory() throws HibernateException {
Configuration configuration = new Configuration();
configuration.configure();
serviceRegistry = new ServiceRegistryBuilder().applySettings(configuration.getProperties()).buildServiceRegistry();
factory = configuration.buildSessionFactory(serviceRegistry);
//return factory;
//factory = new Configuration().configure().buildSessionFactory();
}
catch (Throwable ex)
{
System.err.println("Failed to create sessionFactory object." + ex.toString());
throw new ExceptionInInitializerError(ex);
}
Booktown BT = new Booktown();
/* Add few employee records in database */
Integer bID1 = BT.addBook(10, "Jakiś napis", 10, 30);
Integer bID2 = BT.addBook(20, "Jakiś inny napis", 10, 50);
//Integer bID3 = BT.addBook(30, "John", 10000, 14);
/* List down all the employees */
BT.listBooks();
/* Update employee's records */
BT.updateBook(bID1, 5000);
/* Delete an employee from the database */
BT.deleteBook(bID2);
/* List down new list of the employees */
BT.listBooks();
}
/* Method to CREATE a book in the database */
public Integer addBook(int bid, String fname, int lname, int salary)
{
Session session = factory.openSession();
Transaction tx = null;
Integer bID = null;
try
{
tx = session.beginTransaction();
Books book = new Books(fname, lname, salary);
bid = (Integer) session.save(book);
tx.commit();
}
catch (HibernateException e)
{
if (tx != null)
tx.rollback();
e.printStackTrace();
}
finally
{
session.close();
}
return bID;
}
/* Method to READ all the books */
public void listBooks()
{
Session session = factory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
List<Books> books = session.createQuery("FROM books").list();
for (Iterator<Books> iterator = books.iterator(); iterator.hasNext();)
{
Books book = (Books) iterator.next();
System.out.print("First Name: " + book.getTitle());
System.out.print(" Last Name: " + book.getAuthorId());
System.out.println(" Salary: " + book.getSubjectId());
}
tx.commit();
}
catch (HibernateException e)
{
if (tx != null)
tx.rollback();
e.printStackTrace();
}
finally
{
session.close();
}
}
/* Method to UPDATE author for a book */
public void updateBook(Integer bID, int auth)
{
Session session = factory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
Books book = (Books) session.get(Books.class, bID);
book.setAuthorId(auth);
session.update(book);
tx.commit();
}
catch (HibernateException e)
{
if (tx != null)
tx.rollback();
e.printStackTrace();
}
finally
{
session.close();
}
}
/* Method to DELETE a book from the records */
public void deleteBook(Integer bID)
{
Session session = factory.openSession();
Transaction tx = null;
try
{
tx = session.beginTransaction();
Books book = (Books) session.get(Books.class, bID);
session.delete(book);
tx.commit();
}
catch (HibernateException e)
{
if (tx != null)
tx.rollback();
e.printStackTrace();
}
finally
{
session.close();
}
}
}
代码正在编译，但在运行时我得到：
> paź 15, 2013 8:44:38 PM org.hibernate.hql.internal.ast.ASTQueryTranslatorFactory <init>
INFO: HHH000397: Using ASTQueryTranslatorFactory
Failed to create sessionFactory object.org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
Exception in thread "main" java.lang.ExceptionInInitializerError
at Booktown.main(Booktown.java:34)
Caused by: org.hibernate.MappingException: Could not get constructor for org.hibernate.persister.entity.SingleTableEntityPersister
at org.hibernate.persister.internal.PersisterFactoryImpl.create(PersisterFactoryImpl.java:185)
at org.hibernate.persister.internal.PersisterFactoryImpl.createEntityPersister(PersisterFactoryImpl.java:135)
at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:385)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1790)
at Booktown.main(Booktown.java:25)
Caused by: org.hibernate.HibernateException: Unable to instantiate default tuplizer [org.hibernate.tuple.entity.PojoEntityTuplizer]
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:138)
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructDefaultTuplizer(EntityTuplizerFactory.java:188)
at org.hibernate.tuple.entity.EntityMetamodel.<init>(EntityMetamodel.java:341) at org.hibernate.persister.entity.AbstractEntityPersister.<init>(AbstractEntityPersister.java:507)
at org.hibernate.persister.entity.SingleTableEntityPersister.<init>(SingleTableEntityPersister.java:146)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at org.hibernate.persister.internal.PersisterFactoryImpl.create(PersisterFactoryImpl.java:163)
... 4 more
Caused by: java.lang.reflect.InvocationTargetException at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
at org.hibernate.tuple.entity.EntityTuplizerFactory.constructTuplizer(EntityTuplizerFactory.java:135)
... 13 more
Caused by: org.hibernate.PropertyNotFoundException: Could not find a getter for author_id in class Books
at org.hibernate.property.BasicPropertyAccessor.createGetter(BasicPropertyAccessor.java:316)
at org.hibernate.property.BasicPropertyAccessor.getGetter(BasicPropertyAccessor.java:310)
at org.hibernate.mapping.Property.getGetter(Property.java:321)
at org.hibernate.tuple.entity.PojoEntityTuplizer.buildPropertyGetter(PojoEntityTuplizer.java:444)
at org.hibernate.tuple.entity.AbstractEntityTuplizer.<init>(AbstractEntityTuplizer.java:200)
at org.hibernate.tuple.entity.PojoEntityTuplizer.<init>(PojoEntityTuplizer.java:82)
... 18 more
我发现类似的问题没有二传手。在我的案例中，系统说没有author_id的getter，但它在Books.java的第45行。
某人可以告诉我出了什么问题吗？也许还有一个我没看到的原因......
答案 0 :(得分：5)
public int getAuthorId()
{
return author_id;
}
应该是（observe，author_id）
public int getAuthor_id()
{
return author_id;
}
或者将XML更新为蜘蛛评论的@Boris。
答案 1 :(得分：3)
据我所知，Hibernate需要一个你的Books类似乎没有的无参数构造函数。因此，即使您使保存部分正常工作，我认为您尝试加载时代码也会失败。
因此，创建一个构造函数：
public Books(){
}
Why does Hibernate require no argument constructor?
另外，如前所述，抛弃XML并使用JPA注释。根据标准Java约定，将Books重命名为Book，并从变量名中删除_。
艾伦
答案 2 :(得分：0)
我遇到过这个问题，我就这样解决了： 您应该在NetBeans IDE中生成构造函数，Getter和Setter（我正在使用IDE是netbeans），因此您必须按快捷键ALT + Insert（Mac上的CTLRL + I）。调用快捷方式后，将提供所有可能的生成器。