There isn't a parameter to set the initial value for the increment generator. The initial value of 1 is hardcoded in the org.hibernate.id.IncrementGenerator class.
To solve your problem, you could use your own id generator class.
Following is a working example. It assumes MySQL, but you could use any database with some adjustments.
The example.IncrementGenerator class is a copy of org.hibernate.id.IncrementGenerator, but with code added to set the initial id value from the initial_value parameter.
1. Create test database.
2. Create table (e.g. use create.sql) in test database.
3. Create a user with access to the person table (e.g. user = testuser, pass = testpass)
4. Compile the following:
src\hibernate.cfg.xml
src\example\IncrementGenerator.java,
src\example\Main.java
src\example\Person.hbm.xml
src\example\Person.java
5. Run Main.class
The first inserted record should have id = 100.
To compile, you need these dependencies:
- hibernate 3
To run, you need these dependencies:
- hibernate 3
- MySQL JDBC driver
--- create.sql ---
Code:
create table person (id bigint not null, name varchar(50) not null, primary key (id));
--- src\hibernate.cfg.xml ---
Code:
<?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>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="connection.url">jdbc:mysql://localhost/test</property>
<property name="connection.username">testuser</property>
<property name="connection.password">testpass</property>
<property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<mapping resource="example/Person.hbm.xml"/>
</session-factory>
</hibernate-configuration>
--- src\example\IncrementGenerator.java ---
Code:
package example;
import java.io.Serializable;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.Properties;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.hibernate.HibernateException;
import org.hibernate.MappingException;
import org.hibernate.dialect.Dialect;
import org.hibernate.engine.SessionImplementor;
import org.hibernate.exception.JDBCExceptionHelper;
import org.hibernate.id.Configurable;
import org.hibernate.id.IdentifierGenerator;
import org.hibernate.id.IdentifierGeneratorFactory;
import org.hibernate.id.PersistentIdentifierGenerator;
import org.hibernate.mapping.Table;
import org.hibernate.type.Type;
import org.hibernate.util.StringHelper;
public class IncrementGenerator implements IdentifierGenerator, Configurable {
private static final Log log = LogFactory.getLog(IncrementGenerator.class);
private long next;
private String sql;
private Class returnClass;
private long initialValue;
public synchronized Serializable generate(SessionImplementor session, Object object)
throws HibernateException {
if (sql!=null) {
getNext( session );
}
return IdentifierGeneratorFactory.createNumber(next++, returnClass);
}
public void configure(Type type, Properties params, Dialect dialect)
throws MappingException {
String tableList = params.getProperty("tables");
if (tableList==null) tableList = params.getProperty(PersistentIdentifierGenerator.TABLES);
String[] tables = StringHelper.split(", ", tableList);
String column = params.getProperty("column");
if (column==null) column = params.getProperty(PersistentIdentifierGenerator.PK);
String schema = params.getProperty(PersistentIdentifierGenerator.SCHEMA);
String catalog = params.getProperty(PersistentIdentifierGenerator.CATALOG);
returnClass = type.getReturnedClass();
StringBuffer buf = new StringBuffer();
for ( int i=0; i<tables.length; i++ ) {
if (tables.length>1) {
buf.append("select ").append(column).append(" from ");
}
buf.append( Table.qualify( catalog, schema, tables[i] ) );
if ( i<tables.length-1) buf.append(" union ");
}
if (tables.length>1) {
buf.insert(0, "( ").append(" ) ids_");
column = "ids_." + column;
}
sql = "select max(" + column + ") from " + buf.toString();
initialValue = getLong("initial_value", params, 1);
}
private void getNext( SessionImplementor session ) {
log.debug("fetching initial value: " + sql);
try {
PreparedStatement st = session.getBatcher().prepareSelectStatement(sql);
try {
ResultSet rs = st.executeQuery();
try {
if ( rs.next() ) {
next = rs.getLong(1) + 1;
if ( rs.wasNull() ) next = initialValue;
}
else {
next = initialValue;
}
sql=null;
log.debug("first free id: " + next);
}
finally {
rs.close();
}
}
finally {
session.getBatcher().closeStatement(st);
}
}
catch (SQLException sqle) {
throw JDBCExceptionHelper.convert(
session.getFactory().getSQLExceptionConverter(),
sqle,
"could not fetch initial value for increment generator",
sql
);
}
}
public static long getLong(String property, Properties properties, long defaultValue) {
String propValue = properties.getProperty(property);
return propValue == null ? defaultValue : Long.parseLong(propValue.trim());
}
}
--- src\example\Main.java ---
Code:
package example;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
public class Main {
public static void main(String[] args) throws Exception {
Configuration configuration = new Configuration();
configuration.configure();
SessionFactory sessionFactory = configuration.buildSessionFactory();
Session session = sessionFactory.openSession();
try {
Transaction transaction = session.beginTransaction();
try {
Person person = new Person();
person.setName("John");
session.save(person);
} catch (Exception ex) {
transaction.rollback();
throw ex;
}
transaction.commit();
} finally {
session.close();
}
}
}
--- src\example\Person.hbm.xml ---
Code:
<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="example.Person" table="person">
<id name="id">
<generator class="example.IncrementGenerator">
<param name="initial_value">100</param>
</generator>
</id>
<property name="name"/>
</class>
</hibernate-mapping>
--- src\example\Person.java ---
Code:
package example;
public class Person {
private Long id;
private String name;
public Long getId() {
return id;
}
public String getName() {
return name;
}
public void setId(Long id) {
this.id = id;
}
public void setName(String name) {
this.name = name;
}
}
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