Question

Java代码：

  package hello;

  import org.hibernate.Session;
  import org.hibernate.Transaction;
  import org.hibernate.cfg.Configuration;

public class Message {
 private Long id;
 private String text;
 private Message nextMessage;

 private Message() {}

 public Message(String text) {
  this.text = text;
 }

 public Long getId() {
  return id;
 }

 private void setId(Long id) {
  this.id = id;
 }

 public String getText() {
  return text;
 }

 public void setText(String text) {
  this.text = text;
 }

 public Message getNextMessage() {
  return nextMessage;
  }

 public void setNextMessage(Message nextMessage) {
  this.nextMessage = nextMessage;
 }

 public static void main(String[] args){
    Configuration conf = new Configuration();
    conf.configure("hibernate.cfg.xml");
    System.out.println("Conf Loaded Successfully");
    Session session = conf.buildSessionFactory().openSession();
    Transaction tx = session.beginTransaction();
    Message message = new Message("Hello World");
    session.save(message);
    tx.commit();
    session.close();
    System.out.println("Written to DB successfully");
 }

}

使用Hibernate 4.0.1自动生成Hibernate配置和XML文件

    <?xml version="1.0"?>
        <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
       <!-- Generated Dec 5, 2015 9:20:05 PM by Hibernate Tools 3.4.0.CR1 -->
      <hibernate-mapping>
        <class name="hello.Message" table="MESSAGE">
          <id name="id" type="java.lang.Long">
           <column name="ID" />
           <generator class="assigned" />
        </id>
        <property name="text" type="java.lang.String">
         <column name="TEXT" />
        </property>
        <one-to-one name="nextMessage" class="hello.Message"></one-to-one>
    </class>
</hibernate-mapping>

Hibernate 4.0.1是我的eclipse插件。但我在xmlns中看到了3个。这是问题吗？

项目结构

    hibernateFirst
          src/main/java
             hello
               Message
          src/main/resources
             hello
               Message.hbm.xml
          hibernate.cfg.xml

错误：

      Exception in thread "main" org.hibernate.MappingException: Unknown entity: hello.Message
at org.hibernate.internal.SessionFactoryImpl.getEntityPersister(SessionFactoryImpl.java:776)
at org.hibernate.internal.SessionImpl.getEntityPersister(SessionImpl.java:1520)
at org.hibernate.event.internal.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:100)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:192)
at org.hibernate.event.internal.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:38)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:177)
at org.hibernate.event.internal.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:32)
at org.hibernate.event.internal.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:73)
at org.hibernate.internal.SessionImpl.fireSave(SessionImpl.java:679)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:671)
at org.hibernate.internal.SessionImpl.save(SessionImpl.java:666)
at hello.Message.main(Message.java:49)

请帮我解决。

我刚试过在映射中更改hello / Message。但它不起作用。

Answer 1

xml配置中声明的类名只是＆＃34;消息＆＃34;，不需要＆＃34;你好＆＃34;

有关简单示例，请参阅http://www.tutorialspoint.com/hibernate/hibernate_examples.htm

在一对一的映射中也是如此。

Hibernate - Hello World - 未知实体

1 个答案: