org.alfresco.repo.web.util.paging

Class Paging

java.lang.Object

org.alfresco.repo.web.util.paging.Paging

public class Paging
extends Object

Paging. A utility for maintaining paged indexes for a collection of N items. There are two types of cursor: a) Paged This type of cursor is driven from a page number and page size. Random access within the collection is possible by jumping straight to a page. A simple scroll through the collection is supported by iterating through each next page. b) Windowed This type of cursor is driven from a skip row count and maximum number of rows. Random access is not supported. The collection of items is simply scrolled through from start to end by iterating through each next set of rows. In either case, a paging cursor provides a start row and end row which may be used to extract the items for the page from the collection of N items. A zero (or less) page size or row maximum means "unlimited". Zero or one based Page and Rows indexes are supported. By default, Pages are 1 based and Rows are 0 based. At any time, -1 is returned to represent "out of range" i.e. for next, previous, last page. Pseudo-code for traversing through a collection of N items (10 at a time): Paging paging = new Paging(); Cursor page = paging.createCursor(N, paging.createPage(1, 10)); while (page.isInRange()) { for (long i = page.getStartRow(); i <= page.getEndRow(); i++) { ...collection[i]... } page = paging.createCursor(N, paging.createPage(page.getNextPage(), page.getPageSize()); } Cursor window = paging.createCursor(N, paging.createWindow(0, 10)); while (window.isInRange()) { for (long i = window.getStartRow(); i <= window.getEndRow(); i++) { ...collection[i]... } window = paging.createCursor(N, paging.createWindow(window.getNextPage(), window.getPageSize()); }

Author:

davidc

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	Paging.PageType

Constructor Summary

Constructors

Constructor and Description
Paging()

Method Summary

Modifier and Type	Method and Description
Cursor	createCursor(int totalRows, Page page) Create a Cursor
Page	createPage(int pageNumber, int pageSize) Create a Page
PagedResults	createPagedResult(Object result, Cursor cursor) Create a Paged Result Set
PagedResults	createPagedResults(Object[] results, Cursor cursor) Create a Paged Result Set
Page	createPageOrWindow(Integer pageNumber, Integer pageSize, Integer skipCount, Integer maxItems) Create a Page or Window
Page	createPageOrWindow(Map<String,String> args) Create a Page or Window from standardised request arguments For Paged based index (take precedence over window based index, if both are specified): - request args pageNo => page number index pageSize => size of page For Window based index (as defined by CMIS): - request args (take precedence over header values if both are specified) skipCount => row number start index maxItems => size of page
Page	createUnlimitedPage() Create an unlimited Page
Page	createWindow(int skipRows, int maxRows) Create a Window
boolean	isZeroBasedPage() Is zero based page index? Note: scoped to this paging cursor instance
boolean	isZeroBasedRow() Is zero based row index? Note: scoped to this paging cursor instance
void	setZeroBasedPage(boolean zeroBasedPage) Sets zero based page index Note: scoped to this paging cursor instance
void	setZeroBasedRow(boolean zeroBasedRow) Sets zero based row index Note: scoped to this paging cursor instance

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Paging

public Paging()

Method Detail

setZeroBasedPage

public void setZeroBasedPage(boolean zeroBasedPage)

Sets zero based page index Note: scoped to this paging cursor instance

Parameters:

zeroBasedPage - true => 0 based, false => 1 based

isZeroBasedPage

public boolean isZeroBasedPage()

Is zero based page index? Note: scoped to this paging cursor instance

Returns:

true => 0 based, false => 1 based

setZeroBasedRow

public void setZeroBasedRow(boolean zeroBasedRow)

Sets zero based row index Note: scoped to this paging cursor instance

Parameters:

zeroBasedRow - true => 0 based, false => 1 based

isZeroBasedRow

public boolean isZeroBasedRow()

Is zero based row index? Note: scoped to this paging cursor instance

Returns:

true => 0 based, false => 1 based

createPageOrWindow

public Page createPageOrWindow(Map<String,String> args)

Create a Page or Window from standardised request arguments For Paged based index (take precedence over window based index, if both are specified): - request args pageNo => page number index pageSize => size of page For Window based index (as defined by CMIS): - request args (take precedence over header values if both are specified) skipCount => row number start index maxItems => size of page

Parameters:

args - request args

Returns:

page (if pageNumber driven) or window (if skipCount driven)

createPageOrWindow

public Page createPageOrWindow(Integer pageNumber,
                               Integer pageSize,
                               Integer skipCount,
                               Integer maxItems)

Create a Page or Window

Parameters:

pageNumber - page number (optional and paired with pageSize)

pageSize - page size (optional and paired with pageNumber)

skipCount - skipCount (optional and paired with maxItems)

maxItems - maxItems (optional and paired with skipCount)

Returns:

page (if pageNumber driven) or window (if skipCount driven)

createPage

public Page createPage(int pageNumber,
                       int pageSize)

Create a Page

Parameters:

pageNumber - page number

pageSize - page size

Returns:

the page

createUnlimitedPage

public Page createUnlimitedPage()

Create an unlimited Page

Returns:

page (single Page starting at first page of unlimited page size)

createWindow

public Page createWindow(int skipRows,
                         int maxRows)

Create a Window

Parameters:

skipRows - number of rows to skip

maxRows - maximum number of rows in window

Returns:

the window

createCursor

public Cursor createCursor(int totalRows,
                           Page page)

Create a Cursor

Parameters:

totalRows - total number of rows in cursor (< 0 for don't know)

page - the page / window within cursor

Returns:

the cursor

createPagedResults

public PagedResults createPagedResults(Object[] results,
                                       Cursor cursor)

Create a Paged Result Set

Parameters:

results - the results for the page within the cursor

cursor - the cursor

Returns:

the paged result set

createPagedResult

public PagedResults createPagedResult(Object result,
                                      Cursor cursor)

Create a Paged Result Set

Parameters:

result - the results for the page within the cursor

cursor - the cursor

Returns:

the paged result set