online.sanen.cdm.template.KeyHolder Maven / Gradle / Ivy
package online.sanen.cdm.template;
import java.util.List;
import java.util.Map;
/**
* 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 on 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 online.sanen
* Date:2018年11月10日
* Time:下午1:53:33
*
*/
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
* @throws InvalidDataAccessApiUsageException if multiple keys are encountered.
*/
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
* @throws InvalidDataAccessApiUsageException if keys for multiple rows are encountered
*/
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 being a Map
* of column names and key values
*/
List> getKeyList();
}