org.hibernate.exception.GenericJDBCException: Cannot open connection

org.hibernate.exception.GenericJDBCException: Cannot open connection
org.hibernate.exception.SQLStateConverter.handledNonSpecificException(SQLStateConverter.java:91)
org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:79)
org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:29)
org.hibernate.jdbc.ConnectionManager.openConnection(ConnectionManager.java:307)
org.hibernate.jdbc.ConnectionManager.getConnection(ConnectionManager.java:109)
org.hibernate.jdbc.JDBCContext.connection(JDBCContext.java:134)
org.hibernate.transaction.JDBCTransaction.begin(JDBCTransaction.java:57)
org.hibernate.impl.SessionImpl.beginTransaction(SessionImpl.java:1236)
test.hibernate.factory.CustomerFactory.getAll(CustomerFactory.java:38)
test.hibernate.servlet.CustomerControl.doPost(CustomerControl.java:28)
test.hibernate.servlet.CustomerControl.doGet(CustomerControl.java:77)
javax.servlet.http.HttpServlet.service(HttpServlet.java:689)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

test.util.RequestEncodingFilter.doFilter(RequestEncodingFilter.java:35)

解决方法：由于自己的粗心 忘记加入 连接数据库所需要的jar包