Package eu.bandm.tools.format

Class FormatRepository<K extends Serializable>

java.lang.Object
eu.bandm.tools.format.FormatRepository<K>
@PropertyDependency("user.dir") public abstract class FormatRepository<K extends Serializable> extends Object
A map-like store for formats with serialized resource backing store and on-demand computation.

The intended use is to bundle constant formats bound to static final fields of a class C. If no further action is taken, these are computed at the time class C is loaded. In order to precompute them offline, so that loading class C merely deserializes the formats, do the following:

  1. Declare a static final FormatRepository in class C with context set to C.
  2. Declare static final formats in C initialized by calls to cache(K).
  3. Load class C to compute the formats.
  4. Call store(File) to store the computed formats.
  5. Install the resulting file to the location from where the class is loaded.

For using this class you have to derive a sub-class and implement the only abstract method, toFormat(K), which carries out the effective generation of format objects.
A practical way is to use @code java.lang.String} as the K parameter, and call a parser to derive the format objects from the character sequence forming the key.

This class can also be used in conjunction with dynamically produced formats. The caching functionality is completely available in the dynamic case. But beware that persistent storage of a dynamic collection of formats is only efficient if the actual members do not vary too much from one run of the application to the other, or if a superset of potential members can be approximated ahead of time.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final Class<?>
    context
    The class relative to which the repository will be stored as an resource.
    protected final String
    filename
    The resource filename.
    protected final Map<K,Format>
    formats
    The computed formats.
    protected final String
    name
    A name to identify the repository, if more than one are installed.
    protected boolean
    stored
    Indicates whether the current state has been successfully stored.
    protected static final File
    wd
    Cache for the working directory (at the time of class loading)

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    FormatRepository(Class<?> context, String name)
    Creates a new repository.

  • Method Summary

    Modifier and Type
    Method
    Description
    Format
    cache(K key)
    Computes or retrieves the format for a key.
    void
    clear()
    Removes all computed or loaded formats.
    boolean
    store()
    Stores computed formats relative to the current working directory.
    boolean
    store(File directory)
    Stores computed formats relative to a given directory.
    protected abstract Format
    toFormat(K key)
    Computes the format for a key.

    Methods inherited from class java.lang.Object

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

  • Field Details

    • context

      protected final Class<?> context
      The class relative to which the repository will be stored as an resource.

    • name

      protected final String name
      A name to identify the repository, if more than one are installed.

    • filename

      protected final String filename
      The resource filename. Always set to String.valueOf(context) + "." + name

    • formats

      protected final Map<K extends Serializable,Format> formats
      The computed formats.

    • stored

      protected boolean stored
      Indicates whether the current state has been successfully stored.

    • wd

      protected static final File wd
      Cache for the working directory (at the time of class loading)

  • Constructor Details

    • FormatRepository

      protected FormatRepository(Class<?> context, String name)
      Creates a new repository. The resource name (i.e. filename) for this repository is composed from a context class and a specific name. If the resource is available, the stored formats are loaded.
      Parameters:
      context - the context class.
      name - the name.

  • Method Details

    • cache

      public Format cache(K key)
      Computes or retrieves the format for a key. If the format has already been computed or loaded, it is retrieved. Otherwise, it is computed with toFormat(K).

    • clear

      public void clear()
      Removes all computed or loaded formats.

    • toFormat

      protected abstract Format toFormat(K key)
      Computes the format for a key.

    • store

      public boolean store()
      Stores computed formats relative to the current working directory. as stored in wd.

    • store

      public boolean store(File directory)
      Stores computed formats relative to a given directory. Creates a file directory/filename. Must be installed into the class tree manually in order to be loadable as a resource. The file name is taken from filename. Only first successful invocation will store, all others just return true.
      Parameters:
      directory - where to store the data. This directory is created if it does not exists.
      Returns:
      true if successfully stored with this or an earlier invocation.