初次接触hibernate一些问题搞不懂

Question

我把hibernate的所有包都加到工程里了，建配置文件和影射文件了：
<?xml version="1.0" encoding='UTF-8'?>
<!DOCTYPE hibernate-mapping PUBLIC
                            "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
                            "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" ><!-- DO NOT EDIT: This is a generated file that is synchronized -->
<!-- by MyEclipse Hibernate tool integration.                   -->
<!-- Created Sat Aug 26 23:14:28 CST 2006                         -->
<hibernate-mapping package="cn.db">    <class name="Problem" table="PROBLEM">
 
        <property name="problemid" column="PROBLEMID" type="string"  not-null="true" />
        <property name="scarabid" column="SCARABID" type="string" />
        <property name="nr" column="NR" type="string" />
        <property name="lrr" column="LRR" type="string" />
        <property name="bdid" column="BDID" type="string" />
    </class>
    
</hibernate-mapping><?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"><!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration><session-factory>
<property name="myeclipse.connection.profile">test</property>
<property name="connection.url">
jdbc:oracle:thin:@127.0.0.1:1521:real
</property>
<property name="connection.username">system</property>
<property name="connection.password">manager</property>
<property name="connection.driver_class">
oracle.jdbc.driver.OracleDriver
</property>
<property name="dialect">
org.hibernate.dialect.Oracle9Dialect
</property><mapping resource="cn/db/Problem.hbm.xml"></mapping>
</session-factory></hibernate-configuration>现在搞个测试代码:
package cn.db;import java.io.Serializable;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
import org.hibernate.jdbc.ConnectionManager;
import org.hibernate.*;
import java.util.*;public class Problem
    extends AbstractProblem
    implements Serializable
{ Session session = null;
    public Problem()
    {
     try {
     Configuration config = new Configuration();
     config.addClass(Problem.class);
     //SessionFactory sessionFactory =
     //config.buildSessionFactory();
     //session = sessionFactory.openSession();
     } catch (HibernateException e) {
     e.printStackTrace();
     }    
    
    }
    
    protected void tearDown(){
     try {
     session.close();
     } catch (HibernateException e) {
     e.printStackTrace();
     }
    }
    
    public String queryProblem(){
     String hql=
     " from problem where problemid='11111'";
     List qList=null;
     try {
     Query q = session.createQuery(hql);
     qList=q.list();
    
    
     }catch (HibernateException e) {
     e.printStackTrace();}
     return (String)qList.get(0);
     }
    
    /* Add customized code below */
    public static void main(String arg[]) {     Problem pTest=new Problem();
     //System.out.print("&&&&&&&&&&&&&&"+pTest.queryProblem());
    }
}一初始化就抛出异常了：
IWAV0055I Java Bean cn.db.Problem started with the main method
log4j:WARN No appenders could be found for logger (org.hibernate.cfg.Environment).
log4j:WARN Please initialize the log4j system properly.
org.hibernate.MappingException: Could not read mappings from resource: cn/db/Problem.hbm.xml
at org.hibernate.cfg.Configuration.addClass(Configuration.java:506)
at cn.db.Problem.<init>(Problem.java:39)
at cn.db.Problem.main(Problem.java:74)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:324)
at org.eclipse.ve.internal.java.vce.launcher.remotevm.JavaBeansLauncher.main(JavaBeansLauncher.java:86)
Caused by: org.hibernate.MappingException: invalid mapping
at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:425)
at org.hibernate.cfg.Configuration.addClass(Configuration.java:503)
... 7 more
Caused by: org.xml.sax.SAXParseException: The content of element type "class" must match "(meta*,subselect?,cache?,synchronize*,comment?,tuplizer*,(id|composite-id),discriminator?,natural-id?,(version|timestamp)?,(property|many-to-one|one-to-one|component|dynamic-component|properties|any|map|set|list|bag|idbag|array|primitive-array)*,((join*,subclass*)|joined-subclass*|union-subclass*),loader?,sql-insert?,sql-update?,sql-delete?,filter*,resultset*,(query|sql-query)*)".
at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
at org.apache.xerces.util.ErrorHandlerWrapper.error(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.dtd.XMLDTDValidator.handleEndElement(Unknown Source)
at org.apache.xerces.impl.dtd.XMLDTDValidator.endElement(Unknown Source)
at org.apache.xerces.impl.XMLNSDocumentScannerImpl.scanEndElement(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.dom4j.io.SAXReader.read(SAXReader.java:465)
at org.hibernate.cfg.Configuration.addInputStream(Configuration.java:422)
... 8 more
映射的名字也没错阿，怎么会抛出映射的异常呢？
谢谢！