将Java对象映射到数据库

Question

我正在尝试将Java对象映射到数据库（我正在使用postgres）。 当我运行Java文件（HibernateTest.java）时，它显示很多错误。 我认为所有事情都是正确的。 但是我怀疑我的日食，bcoz不支持xml（我的意思是它没有显示颜色，它没有将xml文件作为已知文件）。 我是一个初学者，所以我无法理解它们。 请给我建议。

hibernate.cfg.xml文件

    <?xml version='1.0' encoding='utf-8'?>

    <hibernate-configuration
        xmlns="http://www.hibernate.org/xsd/hibernate-configuration"
        xsi:schemaLocation="http://www.hibernate.org/xsd/hibernate-configuration hibernate-configuration-4.0.xsd"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
      <session-factory>
      <!-- Database connection settings -->
      <property name="connection.driver_class">org.postgresql.Driver</property>
      <property    name="connection.url">jdbc:hsqldb:hsql://localhost:5432/hibernatedb</property>
    <property name="connection.username">postgres</property>
    <property name="connection.password">hkm@1160</property>

    <!-- JDBC connection pool (use the built-in) -->
    <property name="connection.pool_size">1</property>

    <!-- SQL dialect -->
    <property name="dialect">org.hibernate.dialect.PostgreSQlDialect</property>

    <!-- Enable Hibernate's automatic session context management -->
    <property name="current_session_context_class">thread</property>

    <!-- Disable the second-level cache  -->
    <property name="cache.provider_class">org.hibernate.cache.internal.NoCacheProvider</property>

    <!-- Echo all executed SQL to stdout -->
    <property name="show_sql">true</property>

    <!-- Drop and re-create the database schema on startup -->
    <property name="hbm2ddl.auto">create</property>
    <mapping resource="org.hibernate.hemant.dto.UDestails"/>
  </session-factory>
</hibernate-configuration>

UserDetails.java文件

   package org.hibernate.hemant.dto;
   import javax.persistence.Entity;
   import javax.persistence.Id;

   @Entity
   public class UserDetails 
   {
   @Id
    private int userID;
    private String userName;
    public int getUserID() {
    return userID;
   }
    public void setUserID(int userID) {
    this.userID = userID;
   }
    public String getUserName() {
    return userName;
   }
    public void setUserName(String userName) {
    this.userName = userName;
   }
 }

我的主要Java文件HibernateTest.java

    package org.hemant.hibernate;
    import org.hibernate.Session;
    import org.hibernate.SessionFactory;
    import org.hibernate.cfg.Configuration;
    import org.hibernate.hemant.dto.UserDetails;
    public class HibernateTest {

   /**
   * @param args
   */
    public static void main(String[] args) {
    UserDetails user = new UserDetails();
    user.setUserID(1);
    user.setUserName("First user");
    SessionFactory sessionFactory = new            Configuration().configure().buildSessionFactory();
    Session session = sessionFactory.openSession();
    session.beginTransaction();
    session.save(user);
    session.beginTransaction().commit();
}

}

有错误......

    Apr 13, 2016 9:26:08 PM org.hibernate.Version logVersion
    INFO: HHH000412: Hibernate Core {5.1.0.Final}
    Apr 13, 2016 9:26:08 PM org.hibernate.cfg.Environment <clinit>
    INFO: HHH000206: hibernate.properties not found
    Apr 13, 2016 9:26:08 PM org.hibernate.cfg.Environment buildBytecodeProvider
    INFO: HHH000021: Bytecode provider name : javassistException in thread  "main"
    Exception in thread "main" org.hibernate.internal.util.config.ConfigurationException: Unable to perform unmarshalling at line number 13 and column 63 in RESOURCE hibernate.cfg.xml. Message: cvc-elt.1: Cannot find the declaration of element 'hibernate-configuration'.
at org.hibernate.boot.cfgxml.internal.JaxbCfgProcessor.unmarshal(JaxbCfgProcessor.java:133)
at org.hibernate.boot.cfgxml.internal.JaxbCfgProcessor.unmarshal(JaxbCfgProcessor.java:65)
at org.hibernate.boot.cfgxml.internal.ConfigLoader.loadConfigXmlResource(ConfigLoader.java:57)
at org.hibernate.boot.registry.StandardServiceRegistryBuilder.configure(StandardServiceRegistryBuilder.java:163)
at org.hibernate.cfg.Configuration.configure(Configuration.java:259)
at org.hibernate.cfg.Configuration.configure(Configuration.java:245)
at org.hemant.hibernate.HibernateTest.main(HibernateTest.java:15)
Caused by: javax.xml.bind.UnmarshalException
     - with linked exception:
[org.xml.sax.SAXParseException; lineNumber: 13; columnNumber: 63; cvc-elt.1: Cannot find the declaration of element 'hibernate-configuration'.]
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.handleStreamException(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal0(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallerImpl.unmarshal(Unknown Source)
at org.hibernate.boot.cfgxml.internal.JaxbCfgProcessor.unmarshal(JaxbCfgProcessor.java:126)
... 6 more
    Caused by: org.xml.sax.SAXParseException; lineNumber: 13; columnNumber: 63; cvc-elt.1: Cannot find the declaration of element 'hibernate-configuration'.
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
at com.sun.org.apache.xerces.internal.util.ErrorHandlerWrapper.error(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.XMLErrorReporter.reportError(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.handleStartElement(Unknown Source)
at com.sun.org.apache.xerces.internal.impl.xs.XMLSchemaValidator.startElement(Unknown Source)
at com.sun.org.apache.xerces.internal.jaxp.validation.ValidatorHandlerImpl.startElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.ValidatingUnmarshaller.startElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.InterningXmlVisitor.startElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.StAXEventConnector.handleStartElement(Unknown Source)
at com.sun.xml.internal.bind.v2.runtime.unmarshaller.StAXEventConnector.bridge(Unknown Source)
... 9 more                

Answer 1

导致异常的原因是hibernate.cfg.xml文件不正确。 请使用此结构

<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">

    <hibernate-configuration>
        <session-factory>
           ...
          <mapping class="org.hibernate.hemant.dto.UDestails" />
        </session-factory>
    </hibernate-configuration>

您错误地在hibernate.cfg.xml指定了一个持久类。 您使用带有注释的映射，因此需要映射一个class而不是一个resource

<mapping class="org.hibernate.hemant.dto.UDestails" />

请不要忘记关闭一个session和sessionFactory 。