org.alfresco.repo.web.util

Class PagingCursor

java.lang.Object

org.alfresco.repo.web.util.PagingCursor

public class PagingCursor
extends Object

Paging cursor. 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) Rows 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 and next skip count. Pseudo-code for traversing through a collection of N items (10 at a time): PagingCursor cursor = new PagingCursor(); Page page = cursor.createPageCursor(N, 10, 1); while (page.isInRange()) { for (long i = page.getStartRow(); i <= page.getEndRow(); i++) { ...collection[i]... } page = cursor.createPageCursor(N, 10, page.getNextPage()); } Rows rows = cursor.createRowsCursor(N, 10, 0); while (rows.isInRange()) { for (long i = page.getStartRow(); i <= page.getEndRow(); i++) { ...collection[i]... } rows = cursor.createRowsCursor(N, 10, rows.getNextSkipRows()); }

Author:

davidc

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	PagingCursor.Page Page based Cursor
static class	PagingCursor.Rows Rows based Cursor

Constructor Summary

Constructors

Constructor and Description
PagingCursor()

Method Summary

Modifier and Type	Method and Description
PagingCursor.Page	createPageCursor(long totalRows, int rowsPerPage, int page) Create a Page based Cursor
PagingCursor.Page	createPageCursor(long totalRows, int rowsPerPage, int page, boolean zeroBasedPage, boolean zeroBasedRow) Create a Page based Cursor
PagingCursor.Rows	createRowsCursor(long totalRows, long maxRows, long skipRows) Create a Rows based Cursor
PagingCursor.Rows	createRowsCursor(long totalRows, long maxRows, long skipRows, boolean zeroBasedRow) Create a Rows based Cursor
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

PagingCursor

public PagingCursor()

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

createPageCursor

public PagingCursor.Page createPageCursor(long totalRows,
                                          int rowsPerPage,
                                          int page)

Create a Page based Cursor

Parameters:

totalRows - total rows in collection

rowsPerPage - page size

page - page number (0 or 1 based)

Returns:

Page Cursor

createPageCursor

public PagingCursor.Page createPageCursor(long totalRows,
                                          int rowsPerPage,
                                          int page,
                                          boolean zeroBasedPage,
                                          boolean zeroBasedRow)

Create a Page based Cursor

Parameters:

totalRows - total rows in collection

rowsPerPage - page size

page - page number (0 or 1 based)

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

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

Returns:

Page Cursor

createRowsCursor

public PagingCursor.Rows createRowsCursor(long totalRows,
                                          long maxRows,
                                          long skipRows)

Create a Rows based Cursor

Parameters:

totalRows - total rows in collection

maxRows - maximum number of rows in page

skipRows - number of rows to skip (0 - none)

Returns:

Rows Cursor

createRowsCursor

public PagingCursor.Rows createRowsCursor(long totalRows,
                                          long maxRows,
                                          long skipRows,
                                          boolean zeroBasedRow)

Create a Rows based Cursor

Parameters:

totalRows - total rows in collection

maxRows - maximum number of rows in page

skipRows - number of rows to skip (0 - none)

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

Returns:

Rows Cursor