/*
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hive.storage.jdbc.dao;
import org.apache.hadoop.io.NullWritable;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
/**
* An iterator that allows iterating through a SQL resultset. Includes methods to clear up resources.
*/
public class JdbcRecordIterator implements Iterator<Map<String, String>> {
private static final Logger LOGGER = LoggerFactory.getLogger(JdbcRecordIterator.class);
private Connection conn;
private PreparedStatement ps;
private ResultSet rs;
public JdbcRecordIterator(Connection conn, PreparedStatement ps, ResultSet rs) {
this.conn = conn;
this.ps = ps;
this.rs = rs;
}
@Override
public boolean hasNext() {
try {
return rs.next();
}
catch (Exception se) {
LOGGER.warn("hasNext() threw exception", se);
return false;
}
}
@Override
public Map<String, String> next() {
try {
ResultSetMetaData metadata = rs.getMetaData();
int numColumns = metadata.getColumnCount();
Map<String, String> record = new HashMap<String, String>(numColumns);
for (int i = 0; i < numColumns; i++) {
String key = metadata.getColumnName(i + 1);
String value = rs.getString(i + 1);
record.put(key, value);
}
return record;
}
catch (Exception e) {
LOGGER.warn("next() threw exception", e);
return null;
}
}
@Override
public void remove() {
throw new UnsupportedOperationException("Remove is not supported");
}
/**
* Release all DB resources
*/
public void close() {
try {
rs.close();
ps.close();
conn.close();
}
catch (Exception e) {
LOGGER.warn("Caught exception while trying to close database objects", e);
}
}
}