How to create connection using username and password in salesforce .com using java

public PartnerConnection authenticate(String enterpriseEnvironment,
            String username,
            String password)
            throws ConnectionException {
        PartnerConnection connection;
        ConnectorConfig config = new ConnectorConfig();
        config.setAuthEndpoint(enterpriseEnvironment);
        config.setUsername(username);
        config.setPassword(password);
        try {
            connection = Connector.newConnection(config);
        } catch (ConnectionException e) {
            Logger logger = Logger.getLogger(this.getClass());
            logger.error("Unable to authenticate as '" + username + "'", e);
            throw e;
        }

        return connection;
    }