jview
Class ImageCache

java.lang.Object
  util.PropertyContainer
      util.PropertyResources
          util.PropertyBundles
              jview.ImageCache

All Implemented Interfaces:

Cloneable, ConditionalRefreshing, Initializable, LocalizedSupplying, PropertySupplying, Refreshing, ResourceSupplying

Direct Known Subclasses:

CloudsCache

public class ImageCache
extends PropertyBundles
implements ConditionalRefreshing

A class to monitor an URL for a sequence of images. Two important times have to be distinguished: The main web-site refresh interval, i.e. the time at which the content of the URL is updated to show a new image, and the recording interval of the cache, which is at least as long as the web update interval. If you have a website that delivers an hourly update of an image, but you are only interested in the daily changes, leave the #KEY_WEBUPDATE interval at 3600 000ms, and set the #KEY_CACHEUPDATE to 86400 000ms. Subclasses may load specific images and allow some image-manipulation.

See Also:

Clouds

Nested Class Summary

Nested classes/interfaces inherited from class util.PropertyResources

PropertyResources.URLResource

Field Summary

private SortedMap<Date,BufferedImage>	cache The mapping of retrieval dates to images.
private static int	DEFCACHESIZE Defaults to zero meaning unlimited cache size.
static String	KEY_CACHEREFRESH Forced to be at least the web refresh interval, determines image seq.
static String	KEY_CACHESIZE The maximum cache size.
static String	KEY_IMAGEURL URL to read the cloud image from.
static String	KEY_WEBREFRESH The web refresh interval, the time the URL is updated.
private Date	last The date of the last successful invokation.

Fields inherited from class util.PropertyBundles

KEY_LOCALECOUNTRY, KEY_LOCALELANGUAGE, KEY_RESOURCEBUNDLES

Fields inherited from class util.PropertyResources

KEY_NOINITONCREATE, localurl, locate, POSTFIX_DIR, POSTFIX_EXT, POSTFIX_FILE, POSTFIX_LIST, POSTFIX_URL, urlset

Fields inherited from class util.PropertyContainer

KEY_LISTSEPARATOR, KEY_MAPKEYVALUECHAR, KEY_MAPSEPARATOR

Fields inherited from interface util.ResourceSupplying

KEY_URLRESOURCES, KEY_URLUSECONFIG, KEY_URLUSECURRENT, KEY_URLUSEHOME

Fields inherited from interface util.PropertySupplying

CONFIG, KEY_CLASS

Constructor Summary

ImageCache(Map<String,String> prop)
Defaults only the cache size.

Method Summary

protected BufferedImage	downloadImage(URL address, Date called) The default implementation simply downloads the image and adjusts the time stamp of the image retrieveal to additionally reflect the time it took for downloading.
protected List<URL>	getDownloadURL() In the default implementation we simply return the URL given by the KEY_IMAGEURL.
Date	getLastDate() Returns the last date in the cache.
BufferedImage	getLastImage() Returns the last buffered image in the cache.
long	getRefreshInterval() The refresh interval is our cache intervall, not the web refresh.
void	init() We throw an illegal argument if no download url has been given.
boolean	isFixedRate() We act like a cron, thus return true;
boolean	isRefreshNeeded() We return true if we request a new image.
void	refresh() On refresh, we download the image from the net and store it in the cache if successful.

Methods inherited from class util.PropertyBundles

clone, getLocalized, getLocalized, getLocalizedString, getLocalizedString, loadResource

Methods inherited from class util.PropertyResources

createFrom, createFrom, createFrom, getApplet, getAsResources, getLocalClassLoader, getPropertiesToKey, getPropertiesToKey, getResource, getResourceAsStream, getResourceFromKey, getResources, keyCreate, keyCreate, reload, setApplet

Methods inherited from class util.PropertyContainer

augment, augment, augment, defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsEnums, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, isNew, parseObject, reload, removeProperty, rescanned, setObject, setProperties, setProperty, stringProperties, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface util.ResourceSupplying

getResource, getResourceAsStream, getResources

Methods inherited from interface util.PropertySupplying

defaultBoolean, defaultChar, defaultDouble, defaultFloat, defaultInt, defaultLong, defaultObject, defaultObject, defaultProperties, defaultProperty, getAsBoolean, getAsChar, getAsDouble, getAsFloat, getAsInt, getAsList, getAsLong, getAsMap, getAsObject, getAsObject, getProperties, getProperty, has, parseObject, removeProperty, setObject, setProperty, stringProperties

Field Detail

KEY_IMAGEURL

public static final String KEY_IMAGEURL

URL to read the cloud image from.

See Also:

Constant Field Values

KEY_WEBREFRESH

public static final String KEY_WEBREFRESH

The web refresh interval, the time the URL is updated.

See Also:

Constant Field Values

KEY_CACHEREFRESH

public static final String KEY_CACHEREFRESH

Forced to be at least the web refresh interval, determines image seq.

See Also:

Constant Field Values

KEY_CACHESIZE

public static final String KEY_CACHESIZE

The maximum cache size. Defaults to zero, meaning unlimited cache.

See Also:

Constant Field Values

DEFCACHESIZE

private static final int DEFCACHESIZE

Defaults to zero meaning unlimited cache size.

See Also:

Constant Field Values

cache

private SortedMap<Date,BufferedImage> cache

The mapping of retrieval dates to images.

last

private Date last

The date of the last successful invokation.

Constructor Detail

ImageCache

public ImageCache(Map<String,String> prop)

Defaults only the cache size.

Method Detail

init

public void init()

We throw an illegal argument if no download url has been given. We check the refresh rates to be compatible and create the cache.

Specified by:

init in interface Initializable

Overrides:

init in class PropertyResources

refresh

public void refresh()

On refresh, we download the image from the net and store it in the cache if successful.

Specified by:

refresh in interface Refreshing

isRefreshNeeded

public boolean isRefreshNeeded()

We return true if we request a new image.

Specified by:

isRefreshNeeded in interface ConditionalRefreshing

getRefreshInterval

public long getRefreshInterval()

The refresh interval is our cache intervall, not the web refresh.

Specified by:

getRefreshInterval in interface Refreshing

isFixedRate

public boolean isFixedRate()

We act like a cron, thus return true;

Specified by:

isFixedRate in interface Refreshing

See Also:

Timer

getLastImage

public BufferedImage getLastImage()

Returns the last buffered image in the cache. If used together with getLastDate() consider synchronizing in multithreaded environments.

getLastDate

public Date getLastDate()

Returns the last date in the cache.

getDownloadURL

protected List<URL> getDownloadURL()

In the default implementation we simply return the URL given by the KEY_IMAGEURL.

downloadImage

protected BufferedImage downloadImage(URL address,
                                      Date called)
                               throws IOException

The default implementation simply downloads the image and adjusts the time stamp of the image retrieveal to additionally reflect the time it took for downloading.

Throws:

IOException