Echo Web Framework

The process for localizing an Echo application is the same as that for a standalone/desktop Java application. Localized strings are held in resource bundles that are created for specific target locales. Strings, instead of being hardcoded into the application, are retrieved from these resource bundles based on unique identifiers.

For example, the following code configures buttons with hardcoded English text:

okButton.setText("Ok");
cancelButton.setText("Cancel");

A localized application would instead retrieve the appropriate text for the button from a ResourceBundle:

ResourceBundle resourceBundle 
    = ResourceBundle.getBundle("myapp.Messages",
    ApplicationInstance.getActive().getLocale());
okButton.setText(ResourceBundle.getString("Generic.Cancel"));
cancelButton.setText(ResourceBundle.getString("Generic.Cancel"));

The practice of retrieving all displayed text from resource bundles is encouraged even if an application will not support more than one language. The centralization of all strings enables easy review of all text which can be displayed to the user.

Locale Properties

An Echo ApplicationInstance provides a Locale property which describe its current localization. This property is intended to be set by the application developer as required to the desired localization of the user.

Component Localization: Component provides support for setting a Locale property to describe its localization state and the default localization state for Components beneath it in the hierarchy.

Determining Locale: To determine the localization of a given Component, you may invoke the Component.getRenderLocale() method. This method will query the component, it's ancestors, and finally the ApplicationInstance it is registered to in order to determine the Locale with which the Component should be rendered.

Web Container: Determine Client Browser Locale

An Echo appliaction can be configured to detect the locale of the client on startup and configure its Locale appropriately. This is accomplished using the ClientProperties object which may be obtained from the ServerContext. The following example code demonstrates how the locale can be set based on the client browser:

:
:
import nextapp.echo.webcontainer.ContainerContext;
import nextapp.echo.webrender.ClientProperties;
:
:
public class MyApp extends ApplicationInstance {
  :
  :
  public void init() {
    :
    :
    ContainerContext context = (ContainerContext)
        getContextProperty(ContainerContext.CONTEXT_PROPERTY_NAME);
    ClientProperties clientProperties 
        = context.getClientProperties();
    if (clientProperties.getProperty(ClientProperties.LOCALE) 
       != null) {
      setLocale((Locale) 
          clientProperties.getProperty(ClientProperties.LOCALE));
    }
    :
    :
  }
  :
  :
}

Layout Direction

Echo provides support for languages which are written from left-to-right ("LTR") as well as those which are written right-to-left ("RTL"). Examples of RTL languages include Arabic and Hebrew.

Leading and Trailing Alignment: When developing an application which may be used with RTL languages, the design may call for certain user interface features to be "flipped" to the other side of the screen based on whether an LTR or RTL language is in use. Echo's Alignment property object provides this capability automatically when the Alignment.LEADING or Alignment.TRAILING values are specified for the horizontal property. The Alignment.LEADING value indicates that an item should be positioned or aligned to the left when an LTR language is in use, and to the right when an RTL language. Similarly, the Alignment.TRAILING property indicates that items should be positioned to the right for LTR languages and to the left for RTL languages.