This is my helloworld.reveng.xml
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-reverse-engineering
SYSTEM "http://hibernate.sourceforge.net/hibernate-reverse-engineering-3.0.dtd">
<hibernate-reverse-engineering>
<!--
<table-filter match-name=".*" package="hello" />
-->
<table name="MESSAGES" schema="PUBLIC" class="Message" >
<primary-key>
<generator class="increment" />
<key-column name="MESSAGE_ID" property="id" type="long" />
</primary-key>
<column name="MESSAGE_TEXT" property="text" />
<foreign-key constraint-name="FK_NEXT_MESSAGE">
<many-to-one property="nextMessage" />
<set exclude="true" />
</foreign-key>
</table>

</hibernate-reverse-engineering>

This is my helloworld.db.properties

hibernate.dialect = org.hibernate.dialect.MySQLDialect
hibernate.connection.driver_class = com.mysql.jdbc.Driver
hibernate.connection.url = jdbc:mysql://localhost:3306/hibernatestudy?useUnicode=true&amp;characterEncoding=GBK
hibernate.connection.username = root
hibernate.connection.password =

Sorry,the next is my Messages.hbm.xml,the class is "Messages",not what i wanted "Message",my database is MySQL.
<?xml version="1.0" ?>
<!DOCTYPE hibernate-mapping (View Source for full doctype...)>
- <!-- Generated 2009-6-4 8:36:28 by Hibernate Tools 3.2.0.beta8
-->
- <hibernate-mapping default-cascade="none" default-access="property" default-lazy="true" auto-import="true">
- <class name="Messages" table="messages" catalog="hibernatestudy" mutable="true" polymorphism="implicit" dynamic-update="false" dynamic-insert="false" select-before-update="false" optimistic-lock="version">
<comment />
- <id name="messageId" type="long">
<column name="MESSAGE_ID" />
<generator class="assigned" />
</id>
- <many-to-one name="messages" class="Messages" fetch="select" unique="false" update="true" insert="true" optimistic-lock="true" not-found="exception" embed-xml="true">
- <column name="NEXT_MESSAGE_ID">
<comment />
</column>
</many-to-one>
- <property name="messageText" type="string" unique="false" optimistic-lock="true" lazy="false" generated="never">
- <column name="MESSAGE_TEXT">
<comment />
</column>
</property>
- <set name="messageses" inverse="true" sort="unsorted" mutable="true" optimistic-lock="true" embed-xml="true">
- <key on-delete="noaction">
- <column name="NEXT_MESSAGE_ID">
<comment />
</column>
</key>
<one-to-many class="Messages" not-found="exception" embed-xml="true" />
</set>
</class>
</hibernate-mapping>

and what is your question ?

I expect the name of the class is "Message",but the tools produce "Messages",why?

the schema is not included in your hbm.xml thus you must have set default_schema somewhere ?

most likely the schema is not actually named PUBLIC

Thanks a lot!
I modified the helloworld.db.properties,and added the hibernate.default_schema ,then i received what i wanted.

hibernate.dialect = org.hibernate.dialect.MySQLDialect
hibernate.default_schema = information_schema
hibernate.connection.driver_class = com.mysql.jdbc.Driver
hibernate.connection.url = jdbc:mysql://localhost:3306/hibernatestudy?useUnicode=true&amp;characterEncoding=GBK
hibernate.connection.username = root
hibernate.connection.password =

are you sure your tables are in information_schema ? :)