Accessing JDBC Connection from Java Service

I have created a JDBC Connection. Now I want to write a Java Service for accessing database. Now instead of again re-writing code for getting the database connection, is it possible to use/accee the above create JDBC Connection for getting the connection?
So that from Java service it’s possible to exec SQL’s using the same JDBC Connection.
Also if this is not possible then if I write the code to get connection from the Java Service, then How to avoid getting new connection whenever the Java service gets executed? Is there any way to check if the connection already exists? If yes the use the same else create new connection.
Pl help.