hibernate连不上数据库？

<?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>
<!-- local connection properties -->
<property name="hibernate.connection.url">
jdbc:mysql://192.168.1.90/db_congress?useUnicode=true&amp;characterEncoding=gbk
</property>
<property name="hibernate.connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="hibernate.connection.username">root</property>
<property name="hibernate.connection.password" />
<!-- property name="hibernate.connection.pool_size"></property -->
<!-- dialect for MySQL -->
<property name="dialect">
net.sf.hibernate.dialect.MySQLDialect
</property>
<property name="hibernate.show_sql">false</property>
<property name="hibernate.use_outer_join">true</property>
<property name="hibernate.transaction.factory_class">
net.sf.hibernate.transaction.JDBCTransactionFactory
</property>

<mapping resource="" />
</session-factory>
</hibernate-configuration>