D-Net

package eu.dnetlib.enabling.database.resultset;

import java.util.ArrayList;

import java.util.HashMap;

import java.util.List;

import java.util.Map;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.springframework.jdbc.support.rowset.SqlRowSet;

import eu.dnetlib.enabling.database.rmi.DatabaseException;

import eu.dnetlib.enabling.database.utils.DatabaseUtils;

import eu.dnetlib.enabling.resultset.ResultSetListener;

public class SQLResultSetListener implements ResultSetListener {

	private String db;

	private String sql;

	private DatabaseUtils dbUtils;

	private int lastToPosition = 0;

	private SqlRowSet rowSet = null;

	private Integer size = null;

	private static final Log log = LogFactory.getLog(SQLResultSetListener.class); // NOPMD by marko on 11/24/08 5:02 PM

	protected SQLResultSetListener() {

	}

	protected SQLResultSetListener(String db, String sql, DatabaseUtils dbUtils) {

		super();

		this.db = db;

		this.sql = sql;

		this.dbUtils = dbUtils;

	}

	@Override

	public List<String> getResult(int fromPosition, int toPosition) {

		if (fromPosition < 1) {

			throw new IllegalArgumentException("fromPosition must be >= 1");

		} else if (toPosition < fromPosition) {

			throw new IllegalArgumentException("toPosition must be equal or greater than fromPosition");

		}

		int limit = toPosition - fromPosition + 1;

		try {

			List<String> list = new ArrayList<String>();

			final SqlRowSet rows = getPage(fromPosition, toPosition);

			while (rows.next() && limit-- > 0) {

				Map<?, ?> o = parseRowSet(rows);

				if (o instanceof Map<?, ?>) {

					list.add(dbUtils.rowToDocument((Map<?, ?>) o).asXML());

				}

			}

			lastToPosition = toPosition;

			return list;

		} catch (DatabaseException e) {

			log.error("Error in getResult " + fromPosition + "-" + toPosition, e);

			throw new IllegalStateException("Error in getResult " + fromPosition + "-" + toPosition, e);

		}

	}

	private SqlRowSet getPage(int fromPosition, int toPosition) throws DatabaseException {

		if (fromPosition == lastToPosition + 1 && rowSet != null) {

			log.debug("returning old rowset");

			rowSet.previous();

			return rowSet;

		}

		final int offset = fromPosition - 1;

		String query = sql;

		if (offset > 0) {

			query += " OFFSET " + offset;

		}

		this.rowSet = dbUtils.executeSql(db, query, SqlRowSet.class);

		return rowSet;

	}

	private Map<?, ?> parseRowSet(SqlRowSet rows) {

		HashMap<String, Object> res = new HashMap<String, Object>();

		for (String column : rows.getMetaData().getColumnNames())

			res.put(column, rows.getObject(column));

		return res;

	}

	@Override

	public int getSize() {

		if (size != null) {

			return size;

		}

		String query = "SELECT count(*) FROM ( " + sql + " ) AS TABLELISTENER";

		try {

			this.size = dbUtils.executeSql(db, query, Integer.class);

			return size;

		} catch (DatabaseException e) {

			log.error("Error in getSize, query: " + query, e);

			throw new IllegalStateException("Error in getSize, query: " + query, e);

		}

	}

	public String getDb() {

		return db;

	}

	public void setDb(String db) {

		this.db = db;

	}

	public String getSql() {

		return sql;

	}

	public void setSql(String sql) {

		this.sql = sql;

	}

	public DatabaseUtils getDbUtils() {

		return dbUtils;

	}

	public void setDbUtils(DatabaseUtils dbUtils) {

		this.dbUtils = dbUtils;

	}

}