使用JPA为Spring提供MVC应用程序

i am developing one web application using Spring and that application has connectivity with database so for database connection iam using JPA , now the problem is that i donot know whether i add external jpa jar for databse connection or spring data JPA is enough i donot need to add external jars? and when when i add spring data jpa jars for accessing its crud reporsitory interfaces then i get exception on my application server that failed to connect with localhost 1527 port ...i am developing one web application using Sprin