com.maryanovsky.gwtutils.client
Class Application

java.lang.Object
  com.maryanovsky.gwtutils.client.Application

All Implemented Interfaces:

EntryPoint

public abstract class Application
extends Object
implements EntryPoint

A class which handles much of the heavy lifting of starting up an application. The class handles the following:

• Parses the URL parameters of the page's URL and puts them in URL_ARGS
• Sets the SETTINGS_URL field to the URL of the application settings. By default this is simply "settings.properties", but it can also be specified by a URL parameter named "settingsUrl".
• Enables or disables window scrolling based on the value returned by isWindowScrollingEnabled(), which can be overridden.
• Sets an uncaught exception handler to the value returned by getUncaughtExceptionHandler(), which can be overridden.
• Makes the requests required to start the application. These are specified by getApplicationStartRequests() which can be overridden.
• Once all the requests required to start the application have finished, invokes startApplication(), which should be overridden
.

Author:

Maryanovsky Alexander

Nested Class Summary

static class

Application.RequestMakerResponseHandlerPair

Field Summary

protected static String	SETTINGS_URL The URL of the settings file.
protected ResultCallback<String>	settingsResponseCallback The ResultCallback for the settings request.
protected static Map<String,String>	URL_ARGS The arguments passed to us via the URL.

Constructor Summary

Application()

Method Summary

protected RequestMaker<String>	createSettingsRequestMaker() Creates the request maker for the settings file.
protected List<Application.RequestMakerResponseHandlerPair>	getApplicationStartRequests() Returns the list of requests that need to be made for the application to start and their handlers.
protected GWT.UncaughtExceptionHandler	getUncaughtExceptionHandler() Returns the uncaught exception handler for the application.
protected boolean	isWindowScrollingEnabled() Returns whether window scrolling should be enabled for the application.
protected void	onErrorMakingRequest(String url, String errorMessage) Invoked when making one of the requests required to start the application fails (that is, RequestBuilder.sendRequest(String, RequestCallback) threw a RequestException).
protected void	onErrorRetrievingSettings(String settingsUrl, String errorMessage) This method is called when an error occurs while retrieving the application settings.
protected void	onInvalidSettings(String errorMessage) Invoked when the settings are invalid.
void	onModuleLoad() The entry point method.
protected abstract void	onSettingsReceived(String settingsText) Invoked when the settings are received.
protected abstract void	startApplication() Starts the application.

Methods inherited from class java.lang.Object

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

Field Detail

URL_ARGS

protected static final Map<String,String> URL_ARGS

The arguments passed to us via the URL.

SETTINGS_URL

protected static final String SETTINGS_URL

The URL of the settings file.

settingsResponseCallback

protected final ResultCallback<String> settingsResponseCallback

The ResultCallback for the settings request.

Constructor Detail

Application

public Application()

Method Detail

onModuleLoad

public void onModuleLoad()

The entry point method.

Specified by:

onModuleLoad in interface EntryPoint

getApplicationStartRequests

protected List<Application.RequestMakerResponseHandlerPair> getApplicationStartRequests()

Returns the list of requests that need to be made for the application to start and their handlers. The default implementation returns a list with a single item - the pair (createSettingsRequestMaker(), settingsResponseCallback). If your application needs to retrieve more information in order to start, you should override this method and return additional request builders (and corresponding callbacks).

createSettingsRequestMaker

protected RequestMaker<String> createSettingsRequestMaker()

Creates the request maker for the settings file.

isWindowScrollingEnabled

protected boolean isWindowScrollingEnabled()

Returns whether window scrolling should be enabled for the application. Note that this method is called from onModuleLoad(). The default implementation returns false.

getUncaughtExceptionHandler

protected GWT.UncaughtExceptionHandler getUncaughtExceptionHandler()

Returns the uncaught exception handler for the application. Note that this method is called from onModuleLoad(). The default implementation returns an exception handler which shows an (unlocalized) alert describing the exception that occurred.

onErrorMakingRequest

protected void onErrorMakingRequest(String url,
                                    String errorMessage)

Invoked when making one of the requests required to start the application fails (that is, RequestBuilder.sendRequest(String, RequestCallback) threw a RequestException). The default implementation displays an (unlocalized) alert describing the error that occurred.

onErrorRetrievingSettings

protected void onErrorRetrievingSettings(String settingsUrl,
                                         String errorMessage)

This method is called when an error occurs while retrieving the application settings. The default implementation shows an (unlocalized) alert describing the error.

onSettingsReceived

protected abstract void onSettingsReceived(String settingsText)
                                    throws ParseException

Invoked when the settings are received. The method is meant to parse the settings, and store them in a field until startApplication() is invoked (where they will be used).

Throws:

ParseException

onInvalidSettings

protected void onInvalidSettings(String errorMessage)

Invoked when the settings are invalid. The default implementation shows an (unlocalized) alert describing the error.

startApplication

protected abstract void startApplication()

Starts the application. This method is invoked when all the requests required to start the application have finished. Note that this happens even if some of them failed - it is up to you, when overriding this method, to check whether you have all the information you need.