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
  • Constructor Details

    • Paging

      public Paging()
  • Method Details

    • 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