/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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.hadoop.mapreduce.lib.db;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.classification.InterfaceStability;
import org.apache.hadoop.io.Writable;
/**
* Objects that are read from/written to a database should implement
* <code>DBWritable</code>. DBWritable, is similar to {@link Writable}
* except that the {@link #write(PreparedStatement)} method takes a
* {@link PreparedStatement}, and {@link #readFields(ResultSet)}
* takes a {@link ResultSet}.
* <p>
* Implementations are responsible for writing the fields of the object
* to PreparedStatement, and reading the fields of the object from the
* ResultSet.
*
* <p>Example:</p>
* If we have the following table in the database :
* <pre>
* CREATE TABLE MyTable (
* counter INTEGER NOT NULL,
* timestamp BIGINT NOT NULL,
* );
* </pre>
* then we can read/write the tuples from/to the table with :
* <p><pre>
* public class MyWritable implements Writable, DBWritable {
* // Some data
* private int counter;
* private long timestamp;
*
* //Writable#write() implementation
* public void write(DataOutput out) throws IOException {
* out.writeInt(counter);
* out.writeLong(timestamp);
* }
*
* //Writable#readFields() implementation
* public void readFields(DataInput in) throws IOException {
* counter = in.readInt();
* timestamp = in.readLong();
* }
*
* public void write(PreparedStatement statement) throws SQLException {
* statement.setInt(1, counter);
* statement.setLong(2, timestamp);
* }
*
* public void readFields(ResultSet resultSet) throws SQLException {
* counter = resultSet.getInt(1);
* timestamp = resultSet.getLong(2);
* }
* }
* </pre></p>
*/
@InterfaceAudience.Public
@InterfaceStability.Stable
public interface DBWritable {
/**
* Sets the fields of the object in the {@link PreparedStatement}.
* @param statement the statement that the fields are put into.
* @throws SQLException
*/
public void write(PreparedStatement statement) throws SQLException;
/**
* Reads the fields of the object from the {@link ResultSet}.
* @param resultSet the {@link ResultSet} to get the fields from.
* @throws SQLException
*/
public void readFields(ResultSet resultSet) throws SQLException ;
}