org.hibernate.MappingException: could not instantiate id gen

max88jin · **Joined:** Mon Feb 21, 2005 3:49 am **Posts:** 15

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had no clue what that mean "org.hibernate.MappingException: could not instantiate id gen"

Hibernate version: 3.0.5

Mapping documents:
////////////////////////////// Cat.hbm.xml //////////////////////////////
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >

<hibernate-mapping package="com.cfreecom.club.model">
<class name="Cat" table="cat">
<id
column="cat_id"
name="id"
type="string"
>
<generator class="vm" />
</id>
<property
column="sex"
length="1"
name="sex"
not-null="false"
type="string"
/>
<property
column="name"
length="16"
name="name"
not-null="true"
type="string"
/>
<property
column="weight"
length="10"
name="weight"
not-null="false"
type="big_decimal"
/>
</class>
</hibernate-mapping>
//////////////////////////// hibernate.cfg.xml //////////////////////////////
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-configuration
PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd">

<hibernate-configuration>
<session-factory>

<property name="connection.url">
jdbc:mysql://localhost/club?useUnicode=true&characterEncoding=utf8
</property>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="connection.username">club</property>
<property name="connection.password">club</property>


<property name="dialect">org.hibernate.dialect.MySQLDialect</property>


<property name="connection.pool_size">1</property>

<property name="show_sql">true</property>
<property name="use_outer_join">true</property>
<property name="hibernate.cache.use_query_cache">false</property>
<property name="hibernate.cache.use_second_level_cache">false</property>










<mapping resource="com/cfreecom/club/model/Cat.hbm.xml" />



</session-factory>
</hibernate-configuration>

Code between sessionFactory.openSession() and session.close():
//////////////////////////// CatAction.java //////////////////////////////
import java.util.Iterator;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.struts.action.Action;
import org.apache.struts.action.ActionForm;
import org.apache.struts.action.ActionForward;
import org.apache.struts.action.ActionMapping;

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

import com.cfreecom.club.util.*;
import com.cfreecom.club.model.*;
import com.cfreecom.club.model.dao.*;

public class CatAction extends Action {

public ActionForward execute(ActionMapping mapping, ActionForm form,
HttpServletRequest request, HttpServletResponse response)
throws Exception {

Log log = LogFactory.getLog(CatAction.class);

System.out.println("Hibernate - CatAction ...");

Session session = null;

try {
System.out.println("ActAction ... try ");

session = HibernateUtil.getSession();
System.out.println("HibernateUtil.getSession(): "+session.toString());
Transaction tx = session.beginTransaction();
System.out.println("Transaction: "+tx.toString());
// do your job here ...

Cat cat = new Cat();
cat.setId("Cat1");
cat.setName("Cat1");
cat.setWeight(new java.math.BigDecimal(7.4f));

session.save(cat, session);
System.out.println("session save ");
tx.commit();
System.out.println("trans commit ");

session.close();
} catch (HibernateException e) {
System.out.println("HibernateException: "+e.getMessage());
e.printStackTrace();
} finally {
if(session != null) {
try {
session.close();
System.out.println("session close ");
} catch (HibernateException e) {
System.out.println("HibernateException: "+e.getMessage());
e.printStackTrace();
}
}
}

return (mapping.getInputForward());
}

public void printCol(String str) {
System.out.print(str);
System.out.print(" | ");
}
}
////////////////////////////// HibernateUtil.java /////////////////////////////////
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

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

public class HibernateUtil {

private static Log log = LogFactory.getLog(HibernateUtil.class);

private static SessionFactory sessionFactory = null;

static {
try {
/*
* Use the mappings and properties specified in
* an application resource named hibernate.cfg.xml.
*/
Configuration cfg = new Configuration();
sessionFactory = cfg.configure().buildSessionFactory();
System.out.println("HibernateUtil: "+sessionFactory.toString());
} catch (Throwable t) {
t.printStackTrace();
throw new ExceptionInInitializerError(t);
}

}

public static Session getSession() throws HibernateException {
return sessionFactory.openSession();
}
}
Full stack trace of any exception that occurs:

Name and version of the database you are using: MySQL 4.1.11

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:
Hibernate - CatAction ...
ActAction ... try
11:46:51,806 INFO Environment:464 - Hibernate 3.0.5
11:46:51,807 INFO Environment:477 - hibernate.properties not found
11:46:51,809 INFO Environment:510 - using CGLIB reflection optimizer
11:46:51,812 INFO Environment:540 - using JDK 1.4 java.sql.Timestamp handling
11:46:51,929 INFO Configuration:1110 - configuring from resource: /hibernate.cf g.xml
11:46:51,930 INFO Configuration:1081 - Configuration resource: /hibernate.cfg.x ml
11:46:53,296 INFO Configuration:444 - Mapping resource: com/cfreecom/club/model /Cat.hbm.xml
11:46:55,391 INFO HbmBinder:260 - Mapping class: com.cfreecom.club.model.Cat -> cat
11:46:55,412 INFO Configuration:1222 - Configured SessionFactory: null
11:46:55,416 INFO Configuration:875 - processing extends queue
11:46:55,417 INFO Configuration:879 - processing collection mappings
11:46:55,423 INFO Configuration:888 - processing association property reference s
11:46:55,423 INFO Configuration:917 - processing foreign key constraints
11:46:55,528 INFO DriverManagerConnectionProvider:41 - Using Hibernate built-in connection pool (not for production use!)
11:46:55,528 INFO DriverManagerConnectionProvider:42 - Hibernate connection poo l size: 1
11:46:55,531 INFO DriverManagerConnectionProvider:45 - autocommit mode: false
11:46:55,553 INFO DriverManagerConnectionProvider:80 - using driver: com.mysql. jdbc.Driver at URL: jdbc:mysql://localhost/club?useUnicode=true&characterEncodin g=utf8
11:46:55,554 INFO DriverManagerConnectionProvider:86 - connection properties: { user=club, password=****}
11:46:55,828 INFO SettingsFactory:77 - RDBMS: MySQL, version: 4.1.11-Debian_1-log
11:46:55,829 INFO SettingsFactory:78 - JDBC driver: MySQL-AB JDBC Driver, version: mysql-connector-java-3.1.8 ( $Date: 2005/04/14 20:36:13 $, $Revision: 1.27.4.64 $ )
11:46:55,867 INFO Dialect:92 - Using dialect: org.hibernate.dialect.MySQLDialect
11:46:55,876 INFO TransactionFactoryFactory:31 - Using default transaction strategy (direct JDBC transactions)
11:46:55,879 INFO TransactionManagerLookupFactory:33 - No TransactionManagerLookup configured (in JTA environment, use of read-write or transactional second-level cache is not recommended)
11:46:55,883 INFO SettingsFactory:125 - Automatic flush during beforeCompletion(): disabled
11:46:55,887 INFO SettingsFactory:129 - Automatic session close at end of transaction: disabled
11:46:55,887 INFO SettingsFactory:136 - JDBC batch size: 15
11:46:55,888 INFO SettingsFactory:139 - JDBC batch updates for versioned data: disabled
11:46:55,889 INFO SettingsFactory:144 - Scrollable result sets: enabled
11:46:55,890 INFO SettingsFactory:152 - JDBC3 getGeneratedKeys(): enabled
11:46:55,890 INFO SettingsFactory:160 - Connection release mode: null
11:46:55,896 INFO SettingsFactory:184 - Maximum outer join fetch depth: 2
11:46:55,897 INFO SettingsFactory:187 - Default batch fetch size: 1
11:46:55,897 INFO SettingsFactory:191 - Generate SQL with comments: disabled
11:46:55,898 INFO SettingsFactory:195 - Order SQL updates by primary key: disabled
11:46:55,898 INFO SettingsFactory:334 - Query translator: org.hibernate.hql.ast.ASTQueryTranslatorFactory
11:46:55,903 INFO ASTQueryTranslatorFactory:21 - Using ASTQueryTranslatorFactory
11:46:55,904 INFO SettingsFactory:203 - Query language substitutions: {}
11:46:55,905 INFO SettingsFactory:209 - Second-level cache: disabled
11:46:55,905 INFO SettingsFactory:213 - Query cache: disabled
11:46:55,908 INFO SettingsFactory:228 - Optimize cache for minimal puts: disabled
11:46:55,909 INFO SettingsFactory:237 - Structured second-level cache entries: disabled
11:46:55,920 INFO SettingsFactory:257 - Echoing all SQL to stdout
11:46:55,925 INFO SettingsFactory:261 - Statistics: disabled
11:46:55,926 INFO SettingsFactory:265 - Deleted entity synthetic identifier rollback: disabled
11:46:55,927 INFO SettingsFactory:279 - Default entity-mode: pojo
11:46:56,248 INFO SessionFactoryImpl:152 - building session factory
org.hibernate.MappingException: could not instantiate id generator
at org.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:92)
at org.hibernate.mapping.SimpleValue.createIdentifierGenerator(SimpleValue.java:151)
at org.hibernate.impl.SessionFactoryImpl.<init>(SessionFactoryImpl.java:178)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:1005)
at com.cfreecom.club.util.HibernateUtil.<clinit>(HibernateUtil.java:24)
at com.cfreecom.club.action.CatAction.execute(CatAction.java:40)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:421)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:226)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:397)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:802)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:237)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:157)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:214)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardContextValve.invokeInternal(StandardContextValve.java:198)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:152)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:137)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:118)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:102)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.core.StandardValveContext.invokeNext(StandardValveContext.java:104)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:520)
at org.apache.catalina.core.ContainerBase.invoke(ContainerBase.java:929)
at org.apache.coyote.tomcat5.CoyoteAdapter.service(CoyoteAdapter.java:160)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:799)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.processConnection(Http11Protocol.java:705)
at org.apache.tomcat.util.net.TcpWorkerThread.runIt(PoolTcpEndpoint.java:577)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
at java.lang.Thread.run(Thread.java:595)
Caused by: org.hibernate.MappingException: could not interpret id generator strategy: vm
at org.hibernate.id.IdentifierGeneratorFactory.getIdentifierGeneratorClass(IdentifierGeneratorFactory.java:103)
at org.hibernate.id.IdentifierGeneratorFactory.create(IdentifierGeneratorFactory.java:86)
... 35 more

emmanuel · **Posted:** Mon Jun 06, 2005 6:19 am

<generator class="vm" />
vm is not a regular strategy nor a class implementing IdentifierGenerator