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
  • Constructor Details

    • PagingCursor

      public PagingCursor()
  • 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
    • 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