org.apache.tapestry5.ioc.internal.util
Class URLChangeTracker

java.lang.Object
  org.apache.tapestry5.ioc.internal.util.URLChangeTracker

public class URLChangeTracker
extends Object

Given a (growing) set of URLs, can periodically check to see if any of the underlying resources has changed. This class is capable of using either millisecond-level granularity or second-level granularity. Millisecond-level granularity is used by default. Second-level granularity is provided for compatibility with browsers vis-a-vis resource caching -- that's how granular they get with their "If-Modified-Since", "Last-Modified" and "Expires" headers.

Field Summary

static ClasspathURLConverter

DEFAULT_CONVERTER

Constructor Summary

URLChangeTracker()
Creates a tracker using the default (does nothing) URL converter, with default (millisecond) granularity and folder tracking disabled.

URLChangeTracker(ClasspathURLConverter classpathURLConverter)
Creates a new URL change tracker with millisecond-level granularity and folder checking enabled.

URLChangeTracker(ClasspathURLConverter classpathURLConverter, boolean granularitySeconds)
Creates a new URL change tracker, using either millisecond-level granularity or second-level granularity and folder checking enabled.

URLChangeTracker(ClasspathURLConverter classpathURLConverter, boolean granularitySeconds, boolean trackFolderChanges)
Creates a new URL change tracker, using either millisecond-level granularity or second-level granularity.

Method Summary

long	add(URL url) Stores a new URL into the tracker, or returns the previous time stamp for a previously added URL.
void	clear() Clears all URL and timestamp data stored in the tracker.
boolean	containsChanges() Re-acquires the last updated timestamp for each URL and returns true if any timestamp has changed.
void	forceChange() Needed for testing; changes file timestamps so that a change will be detected by containsChanges().

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_CONVERTER

public static final ClasspathURLConverter DEFAULT_CONVERTER

Constructor Detail

URLChangeTracker

public URLChangeTracker()

Creates a tracker using the default (does nothing) URL converter, with default (millisecond) granularity and folder tracking disabled.

Since:

5.2.1

URLChangeTracker

public URLChangeTracker(ClasspathURLConverter classpathURLConverter)

Creates a new URL change tracker with millisecond-level granularity and folder checking enabled.

Parameters:

classpathURLConverter - used to convert URLs from one protocol to another

URLChangeTracker

public URLChangeTracker(ClasspathURLConverter classpathURLConverter,
                        boolean granularitySeconds)

Creates a new URL change tracker, using either millisecond-level granularity or second-level granularity and folder checking enabled.

Parameters:

classpathURLConverter - used to convert URLs from one protocol to another

granularitySeconds - whether or not to use second granularity (as opposed to millisecond granularity)

URLChangeTracker

public URLChangeTracker(ClasspathURLConverter classpathURLConverter,
                        boolean granularitySeconds,
                        boolean trackFolderChanges)

Creates a new URL change tracker, using either millisecond-level granularity or second-level granularity.

Parameters:

classpathURLConverter - used to convert URLs from one protocol to another

granularitySeconds - whether or not to use second granularity (as opposed to millisecond granularity)

trackFolderChanges - if true, then adding a file URL will also track the folder containing the file (this is useful when concerned about additions to a folder)

Since:

5.2.1

Method Detail

add

public long add(URL url)

Stores a new URL into the tracker, or returns the previous time stamp for a previously added URL. Filters out all non-file URLs.

Parameters:

url - of the resource to add, or null if not known

Returns:

the current timestamp for the URL (possibly rounded off for granularity reasons), or 0 if the URL is null

clear

public void clear()

Clears all URL and timestamp data stored in the tracker.

containsChanges

public boolean containsChanges()

Re-acquires the last updated timestamp for each URL and returns true if any timestamp has changed.

forceChange

public void forceChange()

Needed for testing; changes file timestamps so that a change will be detected by containsChanges().