org.springframework.jdbc.support.KeyHolder Maven / Gradle / Ivy
/*
* Copyright 2002-2019 the original author or authors.
*
* 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
*
* https://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.springframework.jdbc.support;
import java.util.List;
import java.util.Map;
import org.springframework.dao.InvalidDataAccessApiUsageException;
import org.springframework.lang.Nullable;
/**
* Interface for retrieving keys, typically used for auto-generated keys
* as potentially returned by JDBC insert statements.
*
* Implementations of this interface can hold any number of keys.
* In the general case, the keys are returned as a List containing one Map
* for each row of keys.
*
*
Most applications only use one key per row and process only one row at a
* time in an insert statement. In these cases, just call {@code getKey}
* to retrieve the key. The returned value is a Number here, which is the
* usual type for auto-generated keys.
*
* @author Thomas Risberg
* @author Juergen Hoeller
* @since 1.1
* @see org.springframework.jdbc.core.JdbcTemplate
* @see org.springframework.jdbc.object.SqlUpdate
*/
public interface KeyHolder {
/**
* Retrieve the first item from the first map, assuming that there is just
* one item and just one map, and that the item is a number.
* This is the typical case: a single, numeric generated key.
*
Keys are held in a List of Maps, where each item in the list represents
* the keys for each row. If there are multiple columns, then the Map will have
* multiple entries as well. If this method encounters multiple entries in
* either the map or the list meaning that multiple keys were returned,
* then an InvalidDataAccessApiUsageException is thrown.
* @return the generated key as a number
* @throws InvalidDataAccessApiUsageException if multiple keys are encountered
*/
@Nullable
Number getKey() throws InvalidDataAccessApiUsageException;
/**
* Retrieve the first map of keys.
*
If there are multiple entries in the list (meaning that multiple rows
* had keys returned), then an InvalidDataAccessApiUsageException is thrown.
* @return the Map of generated keys for a single row
* @throws InvalidDataAccessApiUsageException if keys for multiple rows are encountered
*/
@Nullable
Map getKeys() throws InvalidDataAccessApiUsageException;
/**
* Return a reference to the List that contains the keys.
* Can be used for extracting keys for multiple rows (an unusual case),
* and also for adding new maps of keys.
* @return the List for the generated keys, with each entry representing
* an individual row through a Map of column names and key values
*/
List> getKeyList();
}