Iam not very clear with your question... my understanding is, you want to connect to the db using DSN (which has userid and password given) and then later get the username in your code after getting connected.
For this, you have to connect using the syntax: Class.forName("sun.jdbc.odbc.JdbcOdbcDriver"); String dsn = "DSN_NAME"; String url = "jdbc dbc:" + dsn; Connection con = DriverManager.getConnection(url);
To get the username in your program after getting connected to the db, you can use getUserName() of DatabaseMetaData interface.
Hope this is what you wanted...
ALternatively, you could even use a Java properties file, say connect.properties, that helps you to set up your database connection at runtime. It could have the following parameters in the form of name/value pair: url=your_URL_here # User name and password user=scott password=tiger
Then, after registering the driver, you could get these parameters from properties file to establish connection and as well have the userid/password available in your program code.