所有已知实现类:
GeneratedKeyHolder
```
public interface KeyHolder
```
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 getKey to retrieve the key. The returned value is a Number here, which is the usual type for auto-generated keys.
从以下版本开始:
1.1
作者:
Thomas Risberg, Juergen Hoeller
另请参阅:
JdbcTemplate, SqlUpdate

方法概要

所有方法实例方法抽象方法
修饰符和类型	方法	说明
`Number`	`getKey()`	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.
`List<Map<String,Object>>`	`getKeyList()`	Return a reference to the List that contains the keys.
`Map<String,Object>`	`getKeys()`	Retrieve the first map of keys.

- 方法详细资料
  - getKey
```
Number getKey()
       throws InvalidDataAccessApiUsageException
```
    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.
    返回:
    the generated key as a number
    抛出:
    InvalidDataAccessApiUsageException - if multiple keys are encountered
  - getKeys
```
Map<String,Object> getKeys()
                          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.
    返回:
    the Map of generated keys for a single row
    抛出:
    InvalidDataAccessApiUsageException - if keys for multiple rows are encountered
  - getKeyList
```
List<Map<String,Object>> getKeyList()
```
    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.
    返回:
    the List for the generated keys, with each entry representing an individual row through a Map of column names and key values

接口 KeyHolder

方法概要

方法详细资料

getKey

getKeys

getKeyList