1 /**
2 * Copyright 2009-2019 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 package org.apache.ibatis.cursor;
17
18 import java.io.Closeable;
19
20 /**
21 * Cursor contract to handle fetching items lazily using an Iterator.
22 * Cursors are a perfect fit to handle millions of items queries that would not normally fits in memory.
23 * If you use collections in resultMaps then cursor SQL queries must be ordered (resultOrdered="true")
24 * using the id columns of the resultMap.
25 *
26 * @author Guillaume Darmont / guillaume@dropinocean.com
27 */
28 public interface Cursor<T> extends Closeable, Iterable<T> {
29
30 /**
31 * @return true if the cursor has started to fetch items from database.
32 */
33 boolean isOpen();
34
35 /**
36 *
37 * @return true if the cursor is fully consumed and has returned all elements matching the query.
38 */
39 boolean isConsumed();
40
41 /**
42 * Get the current item index. The first item has the index 0.
43 * @return -1 if the first cursor item has not been retrieved. The index of the current item retrieved.
44 */
45 int getCurrentIndex();
46 }