gistfile1.java

public interface EntityReader<Type> {

        List<Type> list() throws DAOException;

	Type uniqueResult() throws DAOException;
}


import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

import app.dao.DAOException;
import app.dao.EntityReader;
import app.domain.Song;

public class SongReader implements EntityReader<Song> {

        private ResultSet resultSet;

	public SongReader(ResultSet resultSet) {
		this.resultSet = resultSet;
	}

	@Override
	public List<Song> list() throws DAOException {
		List<Song> results = new ArrayList<Song>();
		try {
			while (resultSet.next()) {
				results.add(readRow());
			}
		} catch (SQLException e) {
			throw new DAOException(e);
		}
		return results;
	}

	@Override
	public Song uniqueResult() throws DAOException {
		try {
			if (!resultSet.next()) {
				return null;
			}
			
			Song song = readRow();

			if (resultSet.next()) {
				throw new DAOException(
						"Zapytanie nie zwróciło unikalnego rezultatu");
			}
			return song;
		} catch (SQLException e) {
			throw new DAOException(e);
		}
	}

	private Song readRow() throws SQLException {
		Song song = new Song();
		long id = resultSet.getLong("song_id");
		song.setId(id);
		String title = resultSet.getString("song_title");
		song.setTitle(title);
		String album = resultSet.getString("song_album");
		song.setAlbum(album);
		String genre = resultSet.getString("song_genre");
		song.setGenre(genre);
		String artist = resultSet.getString("song_artist");
		song.setArtist(artist);
		short year = resultSet.getShort("song_year");
		if (!resultSet.wasNull()) {
			song.setYear(year);
		}		
		return song;
	}
}