org.apache.commons.scaffold.util
Class Scroller

java.lang.Object
  org.apache.commons.scaffold.util.Scroller

public class Scroller

extends java.lang.Object

Scroller tracks the coordinates needed to manage flipping through a result list using LIMIT and OFFSET clauses (or the equivalent). Scrolls through entries using a range (10 to 20 of 50) but does not support paging per se goto page 3 (or entry 30)), though that would be an easy enhancement.

Version:

$Revision: 1.7 $ $Date: 2004/03/21 21:10:10 $

Field Summary

protected int	count The maximum number of entries available (the SQL count).
protected int	entries The actual number of entries to fetch (eg length or limit).
protected int	from The starting point for the current query [FROM].
static int	FROM The default starting point [1].
protected int	limit The maximum number of entries to fetch at a time [Integer.MAX_VALUE].
protected int	next The starting point to use with a "forward" query.
protected java.util.Map	parameters Field for the parameters property [java.util.HashMap].
protected int	prev The starting point to use for a "backward" query.
static int	SCROLL_ROWS The maximum to return with a scrolling list.
protected int	thru The ending point for the current query [1].

Constructor Summary

Scroller()

Scroller(int entries, int from, int limit, int count)

Method Summary

void	calculate() Calculate the new property values using a bean that has already had count and limit set.
void	calculate(int entries) Calculate the new property values using a bean that has already had count and limit set.
void	calculate(int entries, int from, int count, int limit) Calculate the new property values.
int	getCount() Return count.
int	getEntries() Return entries.
int	getFrom() Return from.
java.lang.String	getHiddenFields() Return parameters as a series of hidden HTML fields.
int	getLimit() Return limit.
int	getNext() Return next.
int	getOffset() The database offset for the current query [0].
int	getOffsetForPage(int page) Return first entry for given page.
int	getPage() Return current page number
int	getPage(int thru) Return page number for given entry.
int	getPages() Return number of pages.
java.util.Map	getParameters() Return parameters.
int	getPrev() Return prev.
java.lang.String	getQueryString(java.lang.String uri) Return parameters as a query string for use with a URI.
int	getThru() Return thru.
boolean	isParameters() Set a parameter
void	putParameter(java.lang.String key, java.lang.String value) Set a parameter
void	setCount(int count) Set count
void	setEntries(int entries) Set entries
void	setFrom(int from) Set from.
void	setLimit(int limit) Set limit.
void	setNext(int next) Set next.
void	setParameters(java.util.Map parameters) Set parameters
void	setPrev(int prev) Set prev.
void	setThru(int thru) Set thru.

Methods inherited from class java.lang.Object

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

Field Detail

SCROLL_ROWS

public static final int SCROLL_ROWS

The maximum to return with a scrolling list.

See Also:

Constant Field Values

FROM

public static int FROM

The default starting point [1]. The value is for the convenience of SQL, which is one-based.

from

protected int from

The starting point for the current query [FROM].

thru

protected int thru

The ending point for the current query [1].

prev

protected int prev

The starting point to use for a "backward" query.

next

protected int next

The starting point to use with a "forward" query. This should always be a valid value.

limit

protected int limit

The maximum number of entries to fetch at a time [Integer.MAX_VALUE].

entries

protected int entries

The actual number of entries to fetch (eg length or limit).

count

protected int count

The maximum number of entries available (the SQL count).

parameters

protected java.util.Map parameters

Field for the parameters property [java.util.HashMap].

Constructor Detail

Scroller

public Scroller(int entries,
                int from,
                int limit,
                int count)

Scroller

public Scroller()

Method Detail

setFrom

public void setFrom(int from)

Set from.

Parameters:

from - The new from value.

getFrom

public int getFrom()

Return from.

Returns:

The form value.

setThru

public void setThru(int thru)

Set thru.

Parameters:

thru - The new thru value.

getThru

public int getThru()

Return thru.

Returns:

The form value.

setPrev

public void setPrev(int prev)

Set prev.

Parameters:

prev - The new prev value.

getPrev

public int getPrev()

Return prev.

Returns:

The prev value.

setNext

public void setNext(int next)

Set next.

Parameters:

next - The new next value.

getNext

public int getNext()

Return next.

Returns:

The next value.

setLimit

public void setLimit(int limit)

Set limit.

Parameters:

limit - The new limit value.

getLimit

public int getLimit()

Return limit.

Returns:

The limit value.

setEntries

public void setEntries(int entries)

Set entries

Parameters:

entries - The new entries value.

getEntries

public int getEntries()

Return entries.

Returns:

The entries value.

setCount

public void setCount(int count)

Set count

Parameters:

count - The new count value.

getCount

public int getCount()

Return count.

Returns:

The count value.

setParameters

public void setParameters(java.util.Map parameters)

Set parameters

Parameters:

parameters - The new parameters value.

getParameters

public java.util.Map getParameters()

Return parameters.

Returns:

The parameters value.

putParameter

public void putParameter(java.lang.String key,
                         java.lang.String value)

Set a parameter

Parameters:

key - The parameter name

value - The parameter value

isParameters

public boolean isParameters()

Set a parameter

getQueryString

public java.lang.String getQueryString(java.lang.String uri)

Return parameters as a query string for use with a URI.

Returns:

query string

getHiddenFields

public java.lang.String getHiddenFields()

Return parameters as a series of hidden HTML fields.

Returns:

parameters as a series of hidden HTML fields.

getOffset

public int getOffset()

The database offset for the current query [0]. Convenience method to return one less than from

Returns:

The offset for this query

getPage

public int getPage(int thru)

Return page number for given entry.

Returns:

The number of pages

getPage

public int getPage()

Return current page number

Returns:

The number of pages

getPages

public int getPages()

Return number of pages.

Returns:

The number of pages

getOffsetForPage

public int getOffsetForPage(int page)

Return first entry for given page.

Returns:

first entry for given page

calculate

public void calculate()

Calculate the new property values using a bean that has already had count and limit set.

calculate

public void calculate(int entries)

Calculate the new property values using a bean that has already had count and limit set.

calculate

public void calculate(int entries,
                      int from,
                      int count,
                      int limit)

Calculate the new property values.

Parameters:

entries - The number of matches in this set

from - The first absolute row in this set

count - How many rows in the complete set

limit - The maximum rows in a subset page