1 /*
2 * Copyright 2009-2023 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 * https://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 package org.apache.ibatis.cursor;
17
18 import java.io.Closeable;
19
20 /**
21 * Cursor contract to handle fetching items lazily using an Iterator. Cursors are a perfect fit to handle millions of
22 * items queries that would not normally fit in memory. If you use collections in resultMaps then cursor SQL queries
23 * must be ordered (resultOrdered="true") using the id columns of the resultMap.
24 *
25 * @author Guillaume Darmont / guillaume@dropinocean.com
26 */
27 public interface Cursor<T> extends Closeable, Iterable<T> {
28
29 /**
30 * @return true if the cursor has started to fetch items from database.
31 */
32 boolean isOpen();
33
34 /**
35 * @return true if the cursor is fully consumed and has returned all elements matching the query.
36 */
37 boolean isConsumed();
38
39 /**
40 * Get the current item index. The first item has the index 0.
41 *
42 * @return -1 if the first cursor item has not been retrieved. The index of the current item retrieved.
43 */
44 int getCurrentIndex();
45 }