Package org.apache.tapestry5.ioc.internal.util

Class URLChangeTracker<T>

  • Type Parameters:
    T - The type of the optional information about the tracked resource. This type should implement equals() and hashCode().
    public class URLChangeTracker<T>
extends java.lang.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.

    • Constructor Summary

      Constructors 
      Constructor Description
      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

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      long add​(java.net.URL url)
      Stores a new URL into the tracker, or returns the previous time stamp for a previously added URL.
      long add​(java.net.URL url, T resourceInfo)
      Stores a new URL and associated memo (most probably a related class name) 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().
      java.util.Set<T> getChangedResourcesInfo()
      Re-acquires the last updated timestamp for each URL and returns the non-null resource information for all files with a changed timestamp.
      static java.io.File toFileFromFileProtocolURL​(java.net.URL url)
      Converts a URL with protocol "file" to a File instance.

      • Methods inherited from class java.lang.Object

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

    • 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

      • toFileFromFileProtocolURL

        public static java.io.File toFileFromFileProtocolURL​(java.net.URL url)
        Converts a URL with protocol "file" to a File instance.
        Since:
        5.2.0

      • add

        public long add​(java.net.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

      • add

        public long add​(java.net.URL url,
                T resourceInfo)
        Stores a new URL and associated memo (most probably a related class name) 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
        resourceInfo - an optional object containing information about the tracked URL. It's returned in the getChangedResourcesInfo() method.
        Returns:
        the current timestamp for the URL (possibly rounded off for granularity reasons), or 0 if the URL is null
        Since:
        5.8.3

      • 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.

      • getChangedResourcesInfo

        public java.util.Set<T> getChangedResourcesInfo()
        Re-acquires the last updated timestamp for each URL and returns the non-null resource information for all files with a changed timestamp.

      • forceChange

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