java调用oracle函数

/**
	 * 调用函数取得数据表的ID值
	 * @param tableName 表名
	 * @return
	 * @throws SQLException
	 */
	public String callFun(String tableName) throws SQLException {
		Connection conn = ConnectionFactory.getConnection();
		CallableStatement cstmt = null;
		cstmt = conn.prepareCall("{?

=call getIdBySeq(?)}");
		cstmt.registerOutParameter(1, Types.VARCHAR);
		cstmt.setString(2, tableName);
		cstmt.execute();
		return cstmt.getString(1);
	}

public class ConnectionFactory {

	private ConnectionFactory() {
	}

	private static ComboPooledDataSource ds = null;

	public static synchronized Connection getConnection() {
        Connection con = null;
        ds = new ComboPooledDataSource();
        try {
            con = ds.getConnection();
        } catch (SQLException e1) {
            e1.printStackTrace();
        }
        return con;
    }
}