01: /*
02: * Copyright 2002-2005 the original author or authors.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
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</code>
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: * @since 1.1
39: * @see org.springframework.jdbc.core.JdbcTemplate
40: * @see org.springframework.jdbc.object.SqlUpdate
41: */
42: public interface KeyHolder {
43:
44: /**
45: * Retrieve the first item from the first map, assuming that there is just
46: * one item and just one map, and that the item is a number.
47: * This is the typical case: a single, numeric generated key.
48: * <p>Keys are held in a List of Maps, where each item in the list represents
49: * the keys for each row. If there are multiple columns, then the Map will have
50: * multiple entries as well. If this method encounters multiple entries in
51: * either the map or the list meaning that multiple keys were returned,
52: * then an InvalidDataAccessApiUsageException is thrown.
53: * @return the generated key
54: * @throws InvalidDataAccessApiUsageException if multiple keys are encountered.
55: */
56: Number getKey() throws InvalidDataAccessApiUsageException;
57:
58: /**
59: * Retrieve the first map of keys. If there are multiple entries in the list
60: * (meaning that multiple rows had keys returned), then an
61: * InvalidDataAccessApiUsageException is thrown.
62: * @return the Map of generated keys
63: * @throws InvalidDataAccessApiUsageException if keys for multiple rows are encountered
64: */
65: Map getKeys() throws InvalidDataAccessApiUsageException;
66:
67: /**
68: * Return a reference to the List that contains the keys.
69: * Can be used for extracting keys for multiple rows (an unusual case),
70: * and also for adding new maps of keys.
71: * @return the List for the generated keys, with each entry being a Map
72: * of column names and key values
73: */
74: List getKeyList();
75:
76: }
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