定义PostGIS连接时找不到Oracle Connection

I have an application running with Spring 3.1.1 , Hibernate 3.6.0.Final and Hibernate Spatial 1.1.1 on Tomcat 8.0.20. Until now, we were using Oracle 11.2.0.4 , but we want to migrate to PostgreSQL 9.2-1002.jdbc4 / PostGIS 2.1.6. I have an application running with Spring 3.1.1