Direct Known Subclasses:

LocalContext.Parameter

public abstract class Configurable<T>
extends Object 

 class Document {
 private static final Font FONT
 = Font.decode(System.getProperty("pkg.Document#FONT") != null ?
 System.getProperty("FONT") : "Arial-BOLD-18");
 }

 class Document {
 public static final Configurable<Font> FONT = new Configurable<Font>() {
 @Override
 protected Font getDefault() { 
 new Font("Arial", Font.BOLD, 18);
 }
 };
 }

 class Index {
 // Holds the number of unique preallocated instances (default {@code 1024}). 
 public static final Configurable<Integer> UNIQUE = new Configurable<Integer>() {
 @Override
 protected Integer getDefault() { 
 return 1024;
 }
 @Override
 protected Integer initialized(Integer value) {
 return MathLib.min(value, 65536); // Hard-limiting
 }
 @Override
 protected Integer reconfigured(Integer oldCount, Integer newCount) {
 throw new UnsupportedOperationException("Unicity reconfiguration not supported."); 
 } 
 }
 }

Version:

6.0, July 21, 2013

Author:

Jean-Marie Dautelle

• Nested Class Summary

  Nested Classes

  Modifier and Type	Class and Description
  static interface	Configurable.Listener Services to be published by any one interested in being informed of configurable changes.

• Field Summary

  Fields

  Modifier and Type	Field and Description
  static SecurityContext.Permission<Configurable<?>>	RECONFIGURE_PERMISSION Holds the general permission to reconfigure configurable instances (action "reconfigure").

• Constructor Summary

  Constructors

  Constructor and Description
  Configurable () Creates a new configurable.

• Method Summary

  Methods

  Modifier and Type	Method and Description
  T	get () Returns this configurable value.
  protected abstract T	getDefault () Returns this configurable default value (always different from null).
  String	getName () Returns this configurable name.
  SecurityContext.Permission<Configurable<T>>	getReconfigurePermission () Returns the permission to configure this instance.
  protected T	initialized (T value) This methods is called when the configurable is initialized.
  protected T	parse (String str) Parses the specified text to return the corresponding value.
  T	reconfigure (T newValue) Reconfigures this instance with the specified value if authorized by the SecurityContext.
  protected T	reconfigured (T oldValue, T newValue) This methods is called when the configurable is reconfigured.

  • Methods inherited from class java.lang.Object

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

• Field Detail

  • RECONFIGURE_PERMISSION

    public static SecurityContext.Permission<Configurable<?>> RECONFIGURE_PERMISSION

    Holds the general permission to reconfigure configurable instances (action "reconfigure"). Whether or not that permission is granted depends on the current SecurityContext. It is possible that the general permission to reconfigure a configurable is granted but revoked for a specific instance. Also, the general permission to reconfigure a configurable may be revoked but granted only for a specific instance.

• Constructor Detail

  • Configurable

    public Configurable()

    Creates a new configurable. If a system property exist for this configurable's name, the the parsed value of the property supersedes the default value of this configurable. For example, running the JVM with the option -Djavolution.context.ConcurrentContext#CONCURRENCY=0 disables concurrency support.

• Method Detail

  • get

    public T get()

    Returns this configurable value.

  • getName

    public String getName()

    Returns this configurable name. By convention, the name of the configurable is the name of the static field holding the configurable (e.g. "javolution.context.ConcurrentContext#CONCURRENCY"). This method should be overridden if the enclosing class needs to be impervious to obfuscation or if the enclosing class defines multiple configurable fields.

    Throws:

    UnsupportedOperationException - if the enclosing class has multiple configurable static fields.

  • getReconfigurePermission

    public SecurityContext.Permission<Configurable<T>> getReconfigurePermission()

    Returns the permission to configure this instance.

  • reconfigure

    public T reconfigure(T newValue)

    Reconfigures this instance with the specified value if authorized by the SecurityContext. This method returns the actual new value which may be different from the requested new value (see reconfigured(Object, Object)).

    Parameters:

    newValue - the requested new value.

    Returns:

    the actual new value.

    Throws:

    SecurityException - if the permission to reconfigure this configurable is not granted.

    UnsupportedOperationException - if this configurable does not support dynamic reconfiguration.

  • getDefault

    protected abstract T getDefault()

    Returns this configurable default value (always different from null).

  • initialized

    protected T initialized(T value)

    This methods is called when the configurable is initialized. Developers may override this method to perform any initialization logic (e.g. input validation).

    Parameters:

    value - the requested value for this configurable.

    Returns:

    the actual value of this configurable.

  • parse

    protected T parse(String str)

    Parses the specified text to return the corresponding value. This method is used to initialize this configurable from system properties. The default implementation uses the TextContext to retrieve the text format (based on DefaultTextFormat class annotation).

  • reconfigured

    protected T reconfigured(T oldValue,
     T newValue)

    This methods is called when the configurable is reconfigured. Developers may override this method to perform any reconfiguration logic (e.g. hard limiting values).

    Parameters:

    oldValue - the old value.

    newValue - the requested new value.

    Returns:

    the actual new value of this configurable.

    Throws:

    UnsupportedOperationException - if this configurable does not support dynamic reconfiguration.