java - Hibernate 看不到映射 xml 文件

Question

我是 hibernate 新手，尝试在数据库中写入数据。 我的代码

hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
<session-factory name="postsess">
    <property name="hibernate.connection.driver_class">org.postgresql.Driver</property>
    <property name="hibernate.connection.password">123456</property>
    <property name="hibernate.connection.url">jdbc:postgresql://localhost:5432/postgis</property>
    <property name="hibernate.connection.username">postgres</property>
    <property name="hibernate.default_schema">public</property>
    <property name="hibernate.dialect">org.hibernate.dialect.PostgreSQLDialect</property>
            <!-- Mapping files -->
    <mapping resource="net.sf.hibernate.examples.quickstart.Cat.hbm.xml"/>
</session-factory>
</hibernate-configuration>

HibernateUtin

package net.sf.hibernate.examples.quickstart;

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

import net.sf.hibernate.*;
//import net.sf.hibernate.examples.quickstart.hibernate.cfg.xml;

public class HibernateUtil {

private static final SessionFactory sessionFactory;

static {
    try {
        // Create the SessionFactory
        sessionFactory = new Configuration().configure().buildSessionFactory();
    } catch (HibernateException ex) {
        throw new RuntimeException("Configuration problem: " + ex.getMessage(), ex);
    }
}

public static final ThreadLocal session = new ThreadLocal();

public static Session currentSession() throws HibernateException {
    Session s = (Session) session.get();
    // Open a new Session, if this Thread has none yet
    if (s == null) {
        s = sessionFactory.openSession();
        session.set(s);
    }
    return s;
}

public static void closeSession() throws HibernateException {
    Session s = (Session) session.get();
    session.set(null);
    if (s != null)
        s.close();
}
}

并获得异常(exception)

log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" java.lang.ExceptionInInitializerError
at net.sf.hibernate.examples.quickstart.hib_main.main(hib_main.java:14)
Caused by: java.lang.RuntimeException: Configuration problem: Resource: net.sf.hibernate.examples.quickstart.Cat.hbm.xml not found
at net.sf.hibernate.examples.quickstart.HibernateUtil.<clinit>  (HibernateUtil.java:20)
... 1 more
 Caused by: org.hibernate.MappingException: Resource: net.sf.hibernate.examples.quickstart.Cat.hbm.xml not found
at org.hibernate.cfg.Configuration.addResource(Configuration.java:444)
at org.hibernate.cfg.Configuration.parseMappingElement(Configuration.java:1313)
at org.hibernate.cfg.Configuration.parseSessionFactory(Configuration.java:1285)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1267)
at org.hibernate.cfg.Configuration.doConfigure(Configuration.java:1234)
at org.hibernate.cfg.Configuration.configure(Configuration.java:1162)
at org.hibernate.cfg.Configuration.configure(Configuration.java:1148)
at net.sf.hibernate.examples.quickstart.HibernateUtil.<clinit>(HibernateUtil.java:18)
... 1 more

我做错了什么。它第二次尝试执行简单的示例，并再次出现相同的异常。

更新

在 hibernate.cfg.xml 中更改映射文件的路径后，我在 session.save(princess); 行中得到另一个异常

 log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
Exception in thread "main" org.hibernate.id.IdentifierGenerationException: ids for  this class must be manually assigned before calling save(): net.sf.hibernate.examples.quickstart.Cat
at org.hibernate.id.Assigned.generate(Assigned.java:32)
at org.hibernate.event.def.AbstractSaveEventListener.saveWithGeneratedId(AbstractSaveEventListener.java:85)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.saveWithGeneratedOrRequestedId(DefaultSaveOrUpdateEventListener.java:184)
at org.hibernate.event.def.DefaultSaveEventListener.saveWithGeneratedOrRequestedId(DefaultSaveEventListener.java:33)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.entityIsTransient(DefaultSaveOrUpdateEventListener.java:173)
at org.hibernate.event.def.DefaultSaveEventListener.performSaveOrUpdate(DefaultSaveEventListener.java:27)
at org.hibernate.event.def.DefaultSaveOrUpdateEventListener.onSaveOrUpdate(DefaultSaveOrUpdateEventListener.java:69)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:477)
at org.hibernate.impl.SessionImpl.save(SessionImpl.java:472)
at net.sf.hibernate.examples.quickstart.hib_main.main(hib_main.java:23)

Cat.hbm.xml

<?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 15.08.2012 12:46:22 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
<class name="net.sf.hibernate.examples.quickstart.Cat" table="CAT">
    <id name="id" type="java.lang.String">
        <column name="cat_id" />
        <generator class="assigned" />
    </id>
    <property name="name" type="java.lang.String">
        <column name="name" />
    </property>
    <property name="sex" type="char">
        <column name="sex" />
    </property>
    <property name="weight" type="float">
        <column name="weight" />
    </property>
</class>
</hibernate-mapping>

和主类。

package net.sf.hibernate.examples.quickstart;

import org.hibernate.Session;
import org.hibernate.Transaction;

public class hib_main
{

/**
 * @param args
 */
public static void main(String[] args)
{
    Session session = HibernateUtil.currentSession();

    Transaction tx= session.beginTransaction();

    Cat princess = new Cat();
    princess.setName("Princess");
    princess.setSex('F');
    princess.setWeight(7.4f);

    session.save(princess);
    tx.commit();

    HibernateUtil.closeSession();

}

}

Answer 1

尝试以这种方式定义您的映射资源(使用“/”而不是“.”):

<mapping resource="net/sf/hibernate/examples/quickstart/Cat.hbm.xml"/>

我认为这是您出现问题的原因。

更新:

关于你的第二个问题 - 我认为你忘记在 Cat.hbm.sql 中定义 id 生成策略。例如:

<id name="id" column="CREDIT_CARD_ID" type="long">
    <generator class="native"></generator>
</id>

更新2:

Hibernate 使用它自己的类型。因此，在 id 类型的声明中，您不应该使用 java.lang.String 或 java.lang.Integer，而应该使用简单的字符串和整数。例如，如果您想使用字符串 id，您应该将其定义为:

<id name="id" column="cat_id" type="integer">
    <generator class="native"/>
</id>

Here您可以找到 hibernate 映射类型的列表。