连接库报错

java.sql.SQLException: No suitable driver found for jdbc:oracle:thin:@localhost:1521:orcl

配置文件

<!-- nutz数据源 -->
	<bean id="ds" class="org.nutz.dao.impl.SimpleDataSource">
		<property name="username" value="dnahy2" />
		<property name="password" value="dna" />
		<property name="jdbcUrl" value="jdbc:oracle:thin:@192.168.0.188:1521:orcl" />
	</bean>
// ...省略

tomcat6下一切正常，tomcat7下报错，不知道什么情况。。。求帮忙