org.springframework.beans.support
Class PagedListHolder<E>

java.lang.Object
  org.springframework.beans.support.PagedListHolder<E>

All Implemented Interfaces:

Serializable

public class PagedListHolder<E>
extends Object
implements Serializable

PagedListHolder is a simple state holder for handling lists of objects, separating them into pages. Page numbering starts with 0.

This is mainly targetted at usage in web UIs. Typically, an instance will be instantiated with a list of beans, put into the session, and exported as model. The properties can all be set/get programmatically, but the most common way will be data binding, i.e. populating the bean from request parameters. The getters will mainly be used by the view.

Supports sorting the underlying list via a SortDefinition implementation, available as property "sort". By default, a MutableSortDefinition instance will be used, toggling the ascending value on setting the same property again.

The data binding names have to be called "pageSize" and "sort.ascending", as expected by BeanWrapper. Note that the names and the nesting syntax match the respective JSTL EL expressions, like "myModelAttr.pageSize" and "myModelAttr.sort.ascending".

Since:

19.05.2003

Author:

Juergen Hoeller

See Also:

getPageList(), MutableSortDefinition, Serialized Form

Field Summary

static int	DEFAULT_MAX_LINKED_PAGES
static int	DEFAULT_PAGE_SIZE

Constructor Summary

PagedListHolder()
Create a new holder instance.

PagedListHolder(List<E> source)
Create a new holder instance with the given source list, starting with a default sort definition (with "toggleAscendingOnProperty" activated).

PagedListHolder(List<E> source, SortDefinition sort)
Create a new holder instance with the given source list.

Method Summary

protected SortDefinition	copySortDefinition(SortDefinition sort) Create a deep copy of the given sort definition, for use as state holder to compare a modified sort definition against.
protected void	doSort(List<E> source, SortDefinition sort) Actually perform sorting of the given source list, according to the given sort definition.
int	getFirstElementOnPage() Return the element index of the first element on the current page.
int	getFirstLinkedPage() Return the first page to which create a link around the current page.
int	getLastElementOnPage() Return the element index of the last element on the current page.
int	getLastLinkedPage() Return the last page to which create a link around the current page.
int	getMaxLinkedPages() Return the maximum number of page links to a few pages around the current one.
int	getNrOfElements() Return the total number of elements in the source list.
int	getPage() Return the current page number.
int	getPageCount() Return the number of pages for the current source list.
List<E>	getPageList() Return a sub-list representing the current page.
int	getPageSize() Return the current page size.
Date	getRefreshDate() Return the last time the list has been fetched from the source provider.
SortDefinition	getSort() Return the sort definition for this holder.
List<E>	getSource() Return the source list for this holder.
boolean	isFirstPage() Return if the current page is the first one.
boolean	isLastPage() Return if the current page is the last one.
void	nextPage() Switch to next page.
void	previousPage() Switch to previous page.
void	resort() Resort the list if necessary, i.e.
void	setMaxLinkedPages(int maxLinkedPages) Set the maximum number of page links to a few pages around the current one.
void	setPage(int page) Set the current page number.
void	setPageSize(int pageSize) Set the current page size.
void	setSort(SortDefinition sort) Set the sort definition for this holder.
void	setSource(List<E> source) Set the source list for this holder.

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_PAGE_SIZE

public static final int DEFAULT_PAGE_SIZE

See Also:

Constant Field Values

DEFAULT_MAX_LINKED_PAGES

public static final int DEFAULT_MAX_LINKED_PAGES

See Also:

Constant Field Values

Constructor Detail

PagedListHolder

public PagedListHolder()

Create a new holder instance. You'll need to set a source list to be able to use the holder.

See Also:

setSource(java.util.List)

PagedListHolder

public PagedListHolder(List<E> source)

Create a new holder instance with the given source list, starting with a default sort definition (with "toggleAscendingOnProperty" activated).

Parameters:

source - the source List

See Also:

MutableSortDefinition.setToggleAscendingOnProperty(boolean)

PagedListHolder

public PagedListHolder(List<E> source,
                       SortDefinition sort)

Create a new holder instance with the given source list.

Parameters:

source - the source List

sort - the SortDefinition to start with

Method Detail

setSource

public void setSource(List<E> source)

Set the source list for this holder.

getSource

public List<E> getSource()

Return the source list for this holder.

getRefreshDate

public Date getRefreshDate()

Return the last time the list has been fetched from the source provider.

setSort

public void setSort(SortDefinition sort)

Set the sort definition for this holder. Typically an instance of MutableSortDefinition.

See Also:

MutableSortDefinition

getSort

public SortDefinition getSort()

Return the sort definition for this holder.

setPageSize

public void setPageSize(int pageSize)

Set the current page size. Resets the current page number if changed.

Default value is 10.

getPageSize

public int getPageSize()

Return the current page size.

setPage

public void setPage(int page)

Set the current page number. Page numbering starts with 0.

getPage

public int getPage()

Return the current page number. Page numbering starts with 0.

setMaxLinkedPages

public void setMaxLinkedPages(int maxLinkedPages)

Set the maximum number of page links to a few pages around the current one.

getMaxLinkedPages

public int getMaxLinkedPages()

Return the maximum number of page links to a few pages around the current one.

getPageCount

public int getPageCount()

Return the number of pages for the current source list.

isFirstPage

public boolean isFirstPage()

Return if the current page is the first one.

isLastPage

public boolean isLastPage()

Return if the current page is the last one.

previousPage

public void previousPage()

Switch to previous page. Will stay on first page if already on first page.

nextPage

public void nextPage()

Switch to next page. Will stay on last page if already on last page.

getNrOfElements

public int getNrOfElements()

Return the total number of elements in the source list.

getFirstElementOnPage

public int getFirstElementOnPage()

Return the element index of the first element on the current page. Element numbering starts with 0.

getLastElementOnPage

public int getLastElementOnPage()

Return the element index of the last element on the current page. Element numbering starts with 0.

getPageList

public List<E> getPageList()

Return a sub-list representing the current page.

getFirstLinkedPage

public int getFirstLinkedPage()

Return the first page to which create a link around the current page.

getLastLinkedPage

public int getLastLinkedPage()

Return the last page to which create a link around the current page.

resort

public void resort()

Resort the list if necessary, i.e. if the current sort instance isn't equal to the backed-up sortUsed instance.

Calls doSort to trigger actual sorting.

See Also:

doSort(java.util.List, org.springframework.beans.support.SortDefinition)

copySortDefinition

protected SortDefinition copySortDefinition(SortDefinition sort)

Create a deep copy of the given sort definition, for use as state holder to compare a modified sort definition against.

Default implementation creates a MutableSortDefinition instance. Can be overridden in subclasses, in particular in case of custom extensions to the SortDefinition interface. Is allowed to return null, which means that no sort state will be held, triggering actual sorting for each resort call.

Parameters:

sort - the current SortDefinition object

Returns:

a deep copy of the SortDefinition object

See Also:

MutableSortDefinition.MutableSortDefinition(SortDefinition)

doSort

protected void doSort(List<E> source,
                      SortDefinition sort)

Actually perform sorting of the given source list, according to the given sort definition.

The default implementation uses Spring's PropertyComparator. Can be overridden in subclasses.

See Also:

PropertyComparator.sort(java.util.List, SortDefinition)