pl.gda.pg.eti.ask.przemyslawbielicki.aeh.translation
Class ExceptionTranslator

java.lang.Object
  pl.gda.pg.eti.ask.przemyslawbielicki.aeh.translation.ExceptionTranslator

public class ExceptionTranslator

extends Object

ExceptionTranslator is a singleton class. That means that only one instance of this class can exist.

ExceptionTranslator translates exception given by user to resource path (if translation exists). User that want to retrieve exception translation can automatically add translation for unexistent exception to XML database.

XML database is automatically loaded and saved from and to filesystem.

TODO convert to EJB class

Version:

0.9

Author:

Przemyslaw Bielicki
Gdansk University of Technology
Faculty of Electronics, Telecommunication and Computer Science
Distributed Computer Systems

Field Summary

private static String	databasePath_ Path where XML database is stored - file name
private Hashtable	exceptionTranslations_ Table containing translations for concrete classes.
private static ExceptionTranslator	exceptionTranslator_ Instance of singleton class.
private static boolean	initialized_ Indicates if object is initialized_ or not.

Constructor Summary

private

ExceptionTranslator() Constructor is private to prevent calling it by anyone.

Method Summary

private String	addDefaultTranslation(Throwable throwable) Adds default translation for given exception.
void	addExceptionTranslation(ExceptionTranslation translation) Adds default translation for given exception.
boolean	deserializeTranslations(String fileName) Deserializes translation XML database from file fileName to objects form.
static ExceptionTranslator	getInstance() Typical getInstance method.
String	getTranslation(Throwable throwable) Retrieves translation resource path for given exception.
String	getTranslation(Throwable throwable, boolean addDefault) Retrieves translation resource path for given exception.
boolean	serializeTranslations(String fileName) Serializes translation XML database from objects form to file fileName.
static void	setDatabasePath(String path) Setter method for XML database

Methods inherited from class java.lang.Object

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

Field Detail

exceptionTranslations_

private Hashtable exceptionTranslations_

Table containing translations for concrete classes. Keys in this table are class names ExceptionTranslation.exceptionClass_.

initialized_

private static boolean initialized_

Indicates if object is initialized_ or not.

exceptionTranslator_

private static ExceptionTranslator exceptionTranslator_

Instance of singleton class.

databasePath_

private static String databasePath_

Path where XML database is stored - file name

Constructor Detail

ExceptionTranslator

private ExceptionTranslator()

Constructor is private to prevent calling it by anyone. It is because this class is a singleton.

Method Detail

getInstance

public static ExceptionTranslator getInstance()

Typical getInstance method. If object is not initialized_ this method runs private constructor ExceptionTranslator() and creates a singleton instance.

Returns:

ExceptionTranslator instance

setDatabasePath

public static void setDatabasePath(String path)

Setter method for XML database

Parameters:

path - to XML database

getTranslation

public String getTranslation(Throwable throwable)
                      throws TranslationNotFoundException,
                             ResourceNotDefinedException

Retrieves translation resource path for given exception.

Parameters:

throwable - exception to translate

Returns:

translation resource path

Throws:

TranslationNotFoundException - translation for given exception doesn't exist

ResourceNotDefinedException - translation for given exception exists but resource path is not defined

getTranslation

public String getTranslation(Throwable throwable,
                             boolean addDefault)
                      throws TranslationNotFoundException,
                             ResourceNotDefinedException

Retrieves translation resource path for given exception. If there is no translation in XML database for given exception and addDefault argument is set to true default translation for given exception is added to XML structure. If addDefault argument is set to false this method is equal getTranslation(Throwable)

Parameters:

throwable - exception to translate

Returns:

translation resource path

Throws:

TranslationNotFoundException - translation for given exception doesn't exist

ResourceNotDefinedException - translation for given exception exists but resource path is not defined

See Also:

getTranslation(Throwable, boolean)

addDefaultTranslation

private String addDefaultTranslation(Throwable throwable)

Adds default translation for given exception. If there doesn't exist translation for throwable class this method adds this class to XML database. Next message translation is added to database. Please remember that newly added translation for given exception is not configured in database (in the meaning that its translation resource is null).

Parameters:

throwable - exception to add default translation for

addExceptionTranslation

public void addExceptionTranslation(ExceptionTranslation translation)
                             throws DuplicateTranslationException

Adds default translation for given exception. If translation for translation class ExceptionTranslation.exceptionClass_ already exists DuplicateTranslationException is thrown.

Parameters:

translation - translation to add to XML database

Throws:

DuplicateTranslationException - is thrown when translation for given class already exists

deserializeTranslations

public boolean deserializeTranslations(String fileName)

Deserializes translation XML database from file fileName to objects form. Simply creates objects structure from XML file.

Parameters:

fileName - path to file where translation XML database is

Returns:

true when deserializing finishes correctly and false in other case

serializeTranslations

public boolean serializeTranslations(String fileName)

Serializes translation XML database from objects form to file fileName. Simply creates XML document and then writes it to file.

Parameters:

fileName - path to file where translation XML database is

Returns:

true when serializing finishes correctly and false in other case