|
1
|
/**
|
|
2
|
* Copyright (C) 2012 EDIT
|
|
3
|
* European Distributed Institute of Taxonomy
|
|
4
|
* http://www.e-taxonomy.eu
|
|
5
|
*
|
|
6
|
* The contents of this file are subject to the Mozilla Public License Version 1.1
|
|
7
|
* See LICENSE.TXT at the top of this package for the full license terms.
|
|
8
|
*/
|
|
9
|
package eu.etaxonomy.cdm.api.service.pager;
|
|
10
|
|
|
11
|
import java.util.List;
|
|
12
|
|
|
13
|
import eu.etaxonomy.cdm.api.service.pager.impl.AbstractPagerImpl;
|
|
14
|
|
|
15
|
/**
|
|
16
|
* @see also class <code>eu.etaxonomy.cdm.remote.controller.util.PagerParameter</code>
|
|
17
|
*
|
|
18
|
* @author a.kohlbecker
|
|
19
|
\* @since Dec 10, 2012
|
|
20
|
*
|
|
21
|
*/
|
|
22
|
public class PagerUtils {
|
|
23
|
|
|
24
|
/**
|
|
25
|
* Returns the start index for the given page size and page index values
|
|
26
|
* by multiplying both values (startFor = pageSize * pageIndex).<BR>
|
|
27
|
* If page size is <code>null</code>, either <code>null</code> is returned
|
|
28
|
* or an exception is thrown if page index is > 0.
|
|
29
|
* If page index is null it is assumed as 0.
|
|
30
|
*
|
|
31
|
* @param pageSize the page size
|
|
32
|
* @param pageIndex the page index
|
|
33
|
* @return the start index
|
|
34
|
* @throws PagerRangeException if pageSize == null and pageIndex > 0
|
|
35
|
*/
|
|
36
|
public static Integer startFor(Integer pageSize, Integer pageIndex) throws PagerRangeException {
|
|
37
|
if(pageIndex == null) {
|
|
38
|
pageIndex = 0;
|
|
39
|
}
|
|
40
|
if(pageSize == null){
|
|
41
|
if (pageIndex > 0 ){
|
|
42
|
throw new PagerRangeException("Page index must be undefined or 0 for undefined page size but was " + pageIndex);
|
|
43
|
}else{
|
|
44
|
return null;
|
|
45
|
}
|
|
46
|
}
|
|
47
|
return pageSize * pageIndex;
|
|
48
|
}
|
|
49
|
|
|
50
|
/**
|
|
51
|
* Returns the limit value as used in SQL/HQL statements for the given
|
|
52
|
* page size.<BR>
|
|
53
|
* Earlier, for <code>null</code> the value 0 was returned but as
|
|
54
|
* it was decided that pageSize = <code>null</code> should not set any limitation
|
|
55
|
* it was changed to return value <code>null</code>. This way the current implementation
|
|
56
|
* is the identity function and has no effect except for documentation.
|
|
57
|
* <code>null</code> should be handled in dao-s or specialized code such as
|
|
58
|
* {@link #pageList(List, Integer, Integer)}.
|
|
59
|
*
|
|
60
|
* @param pageSize
|
|
61
|
* @return
|
|
62
|
*/
|
|
63
|
public static Integer limitFor(Integer pageSize) {
|
|
64
|
if(pageSize == null){
|
|
65
|
return null;
|
|
66
|
}else{
|
|
67
|
return pageSize;
|
|
68
|
}
|
|
69
|
}
|
|
70
|
|
|
71
|
/**
|
|
72
|
* The original method {@link AbstractPagerImpl#hasResultsInRange(Long, Integer, Integer)} is
|
|
73
|
* hard to find, therefore this method has been wired also into this Utility class
|
|
74
|
* this this is looked up more frequently.
|
|
75
|
*
|
|
76
|
* @param numberOfResults
|
|
77
|
* @param pageIndex
|
|
78
|
* @param pageSize
|
|
79
|
* @return
|
|
80
|
*/
|
|
81
|
public static boolean hasResultsInRange(Long numberOfResults, Integer pageIndex, Integer pageSize) {
|
|
82
|
return AbstractPagerImpl.hasResultsInRange(numberOfResults, pageIndex, pageSize);
|
|
83
|
}
|
|
84
|
|
|
85
|
/**
|
|
86
|
* Returns a synchronized (sub)list of fullList which contains only the items
|
|
87
|
* for the given page
|
|
88
|
* @param fullList
|
|
89
|
* @param pageIndex page index
|
|
90
|
* @param pageSize page size
|
|
91
|
* @return a synchronized list holding the page items
|
|
92
|
*/
|
|
93
|
public static <T extends Object> List<T> pageList(List<T> fullList, Integer pageIndex, Integer pageSize ){
|
|
94
|
Integer start = startFor(pageSize, pageIndex);
|
|
95
|
if (start == null){
|
|
96
|
return fullList;
|
|
97
|
}
|
|
98
|
Integer limit = limitFor(pageSize); //no effect and never null at this point due to startFor semantics
|
|
99
|
limit = Math.min(Integer.MAX_VALUE - start, limit);
|
|
100
|
|
|
101
|
if (fullList.size() > start) {
|
|
102
|
Integer toIndex = Math.min(fullList.size(), start + limit);
|
|
103
|
return fullList.subList(start, toIndex);
|
|
104
|
}else{
|
|
105
|
return fullList.subList(fullList.size(), fullList.size()); //empty list
|
|
106
|
}
|
|
107
|
}
|
|
108
|
|
|
109
|
}
|