How do I make my Java application identify itself to Oracle on connection?

There is also an Oracle function:

dbms_application_info.set_client_info('Client Info');

which sets the ClientInfo column in v$session.

This might be useful if you only have access to the Connection rather than the underlying DataSource or DriverManager.

java.util.Properties props = new java.util.Properties();
props.setProperty("password","mypassword");
props.setProperty("user","myusername");
props.put("v$session.osuser", System.getProperty("user.name").toString());
props.put("v$session.machine", InetAddress.getLocalHost().getCanonicalHostName());
props.put("v$session.program", "My Program Name");
DriverManager.registerDriver (new oracle.jdbc.OracleDriver());
Connection conn=
    DriverManager.getConnection("jdbc:oracle:thin:@myhostname:1521:mysid", props);

SQL>select username,osuser,program,machine
from v$session
where username = 'ROB'; 

USERNAME  OSUSER       PROGRAM             MACHINE
--------- -----------  ------------------  -----------
ROB       rmerkw       My Program Name     machine

At application level you can use the following methods to set client_info, module and action in v$session:

dbms_application_info.set_client_info
dbms_application_info.set_module
dbms_application_info.set_action