1 /*
2 * Copyright 2002-2012 the original author or authors.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package org.springframework.jdbc.support;
18
19 import java.util.List;
20 import java.util.Map;
21
22 import org.springframework.dao.InvalidDataAccessApiUsageException;
23
24 /**
25 * Interface for retrieving keys, typically used for auto-generated keys
26 * as potentially returned by JDBC insert statements.
27 *
28 * <p>Implementations of this interface can hold any number of keys.
29 * In the general case, the keys are returned as a List containing one Map
30 * for each row of keys.
31 *
32 * <p>Most applications only use on key per row and process only one row at a
33 * time in an insert statement. In these cases, just call {@code getKey}
34 * to retrieve the key. The returned value is a Number here, which is the
35 * usual type for auto-generated keys.
36 *
37 * @author Thomas Risberg
38 * @author Juergen Hoeller
39 * @since 1.1
40 * @see org.springframework.jdbc.core.JdbcTemplate
41 * @see org.springframework.jdbc.object.SqlUpdate
42 */
43 public interface KeyHolder {
44
45 /**
46 * Retrieve the first item from the first map, assuming that there is just
47 * one item and just one map, and that the item is a number.
48 * This is the typical case: a single, numeric generated key.
49 * <p>Keys are held in a List of Maps, where each item in the list represents
50 * the keys for each row. If there are multiple columns, then the Map will have
51 * multiple entries as well. If this method encounters multiple entries in
52 * either the map or the list meaning that multiple keys were returned,
53 * then an InvalidDataAccessApiUsageException is thrown.
54 * @return the generated key
55 * @throws InvalidDataAccessApiUsageException if multiple keys are encountered.
56 */
57 Number getKey() throws InvalidDataAccessApiUsageException;
58
59 /**
60 * Retrieve the first map of keys. If there are multiple entries in the list
61 * (meaning that multiple rows had keys returned), then an
62 * InvalidDataAccessApiUsageException is thrown.
63 * @return the Map of generated keys
64 * @throws InvalidDataAccessApiUsageException if keys for multiple rows are encountered
65 */
66 Map<String, Object> getKeys() throws InvalidDataAccessApiUsageException;
67
68 /**
69 * Return a reference to the List that contains the keys.
70 * Can be used for extracting keys for multiple rows (an unusual case),
71 * and also for adding new maps of keys.
72 * @return the List for the generated keys, with each entry being a Map
73 * of column names and key values
74 */
75 List<Map<String, Object>> getKeyList();
76
77 }