What architecture to follow to connect to multiple databases

Dear All, I'm building a core java application in which i have say 20 databases an开发者_运维知识库d want to connect to each of them depending upon from where request has come to access which database.

I want to connect to databases only once from where i can pick the connection and return; please suggest what type of architecture to follow.

You have to keep a list of connection pools.

I would use a Map< String, ConnectionPool >, where the key is the connection id. When you need a connection, you take it from this map :

Connection connectionDbAccounts = connectionMap.get("accounts").getConnection();
// Use connectionDbAccounts...
connectionDbAccounts.close();

Use a HashMap<Location, DatabaseConnection> ?