/*
* The MIT License (MIT)
*
* Copyright (c) 2007-2015 Broad Institute
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
package org.broad.igv.dev.db;
import org.apache.log4j.Logger;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
/**
* Class for reading only portions of a table (queries) repeatedly.
* The connection is NOT closed between queries.
*
* @author Jacob Silterra
* @date 2012/05/30
*/
public abstract class DBQueryReader<T> extends DBReader {
private static Logger log = Logger.getLogger(DBQueryReader.class);
protected DBProfile.DBTable table;
public DBQueryReader(DBProfile.DBTable table) {
super(table);
this.table = table;
}
protected Iterator loadIterator(PreparedStatement st) {
try {
ResultSet rs = st.executeQuery();
return loadIterator(rs);
} catch (SQLException e) {
log.error("Database error", e);
throw new RuntimeException("Database error", e);
}
}
/**
* Load all results from the provided {@code ResultSet}
* so we can close it quickly
* @param rs
* @return
*/
protected Iterator loadIterator(ResultSet rs) {
List<T> results = new ArrayList<T>();
try {
while (rs.next()) {
results.add(processResult(rs));
}
} catch (SQLException e) {
log.error("Database error", e);
throw new RuntimeException("Database error", e);
} finally {
DBManager.closeAll(rs);
}
return results.iterator();
}
/**
* Read a single line from the {@code ResultSet} and return the object
* based on it.
* @param rs
* @return
* @throws SQLException
*/
protected abstract T processResult(ResultSet rs) throws SQLException;
}