问题描述

第一次使用hibernate就出错

使用hibernate4报错
Initial SessionFactory creation failed.java.lang.NullPointerException
Exception in thread ""main"" java.lang.ExceptionInInitializerError
at HibernateUtil.buildSessionFactory(HibernateUtil.java:22)
at HibernateUtil.(HibernateUtil.java:9)
at TestStudent.main(TestStudent.java:22)
Caused by: java.lang.NullPointerException
at HibernateUtil.buildSessionFactory(HibernateUtil.java:16)
... 2 more

mysql—connector-java使用的版本是5.1.22
hibernate使用的版本是4.3.5

以下是程序：

TestStudent.java
import javax.imageio.spi.ServiceRegistry;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import com.bjsxt.hibernate.model.Student;
public class TestStudent {
public static void main(String args[]){
Student s=new Student();
s.setId(1);
s.setName(""s1"");
s.setAge(1);
SessionFactory sf=HibernateUtil.getSessionFactory();
Session session=sf.openSession();
session.beginTransaction();
session.save(s);
session.getTransaction().commit();
session.close();
sf.close();
}

}

HibernateUtil.java
import org.hibernate.SessionFactory;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;
import org.hibernate.cfg.Configuration;
public class HibernateUtil {
private static final SessionFactory sessionFactory = buildSessionFactory();
private static Configuration cfg=new Configuration();
private static SessionFactory buildSessionFactory() {
try {
return cfg.configure().buildSessionFactory(new StandardServiceRegistryBuilder().build());
}
catch (Throwable ex) {
// Make sure you log the exception as it might be swallowed
System.err.println(""Initial SessionFactory creation failed."" + ex);

        throw new ExceptionInInitializerError(ex);    }}public static SessionFactory getSessionFactory() {    return sessionFactory;}

}
hibernate.cfg.xml
<?xml version='1.0' encoding='utf-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
-//Hibernate/Hibernate Configuration DTD 3.0//EN""
http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"">

<session-factory>    <property name=""javax.persistence.validation.mode"">none</property>     <!-- Database connection settings -->    <property name=""connection.driver_class"">com.mysql.jdbc.Driver</property>    <property name=""connection.url"">jdbc:mysql://localhost/hibernate</property>    <property name=""connection.username"">ru</property>    <property name=""connection.password"">qq</property>    <!-- JDBC connection pool (use the built-in) -->    <!--<property name=""connection.pool_size"">1</property>-->    <!-- SQL dialect -->    <property name=""dialect"">org.hibernate.dialect.MySQLDialect</property>    <!-- Enable Hibernate's automatic session context management -->    <!--<property name=""current_session_context_class"">thread</property>-->    <!-- Disable the second-level cache  -->    <property name=""cache.provider_class"">org.hibernate.cache.internal.NoCacheProvider</property>    <!-- Echo all executed SQL to stdout -->    <property name=""show_sql"">true</property>    <!-- Drop and re-create the database schema on startup -->    <!--<property name=""hbm2ddl.auto"">update</property>-->   <mapping resource=""com/bjsxt/hibernate/model/Student.hbm.xml""/> </session-factory>

student.hbm.xml
<?xml version=""1.0""?>
<!DOCTYPE hibernate-mapping PUBLIC
-//Hibernate/Hibernate Mapping DTD 3.0//EN""
http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd"">