org.apache.commons.dbutils.handlers.ColumnListHandler Maven / Gradle / Ivy
/*
* 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.commons.dbutils.handlers;
import java.sql.ResultSet;
import java.sql.SQLException;
/**
* ResultSetHandler implementation that converts one
* ResultSet column into a List of
* Objects. This class is thread safe.
*
* @param The type of the column.
* @see org.apache.commons.dbutils.ResultSetHandler
* @since DbUtils 1.1
*/
public class ColumnListHandler extends AbstractListHandler {
/**
* The column number to retrieve.
*/
private final int columnIndex;
/**
* The column name to retrieve. Either columnName or columnIndex
* will be used but never both.
*/
private final String columnName;
/**
* Creates a new instance of ColumnListHandler. The first column of each
* row will be returned from handle().
*/
public ColumnListHandler() {
this(1, null);
}
/**
* Creates a new instance of ColumnListHandler.
*
* @param columnIndex The index of the column to retrieve from the
* ResultSet.
*/
public ColumnListHandler(int columnIndex) {
this(columnIndex, null);
}
/**
* Creates a new instance of ColumnListHandler.
*
* @param columnName The name of the column to retrieve from the
* ResultSet.
*/
public ColumnListHandler(String columnName) {
this(1, columnName);
}
/** Private Helper
* @param columnIndex The index of the column to retrieve from the
* ResultSet.
* @param columnName The name of the column to retrieve from the
* ResultSet.
*/
private ColumnListHandler(int columnIndex, String columnName) {
super();
this.columnIndex = columnIndex;
this.columnName = columnName;
}
/**
* Returns one ResultSet column value as Object.
* @param rs ResultSet to process.
* @return Object, never null.
*
* @throws SQLException if a database access error occurs
* @throws ClassCastException if the class datatype does not match the column type
*
* @see org.apache.commons.dbutils.handlers.AbstractListHandler#handle(ResultSet)
*/
// We assume that the user has picked the correct type to match the column
// so getObject will return the appropriate type and the cast will succeed.
@SuppressWarnings("unchecked")
@Override
protected T handleRow(ResultSet rs) throws SQLException {
if (this.columnName == null) {
return (T) rs.getObject(this.columnIndex);
} else {
return (T) rs.getObject(this.columnName);
}
}
}