org.apache.wicket.resource.loader
Class ComponentStringResourceLoader

java.lang.Object
  org.apache.wicket.resource.loader.ComponentStringResourceLoader

All Implemented Interfaces:

IStringResourceLoader

Direct Known Subclasses:

ClassStringResourceLoader

public class ComponentStringResourceLoader
extends java.lang.Object
implements IStringResourceLoader

This is Wicket's default string resource loader.

The component based string resource loader attempts to find the resource from a bundle that corresponds to the supplied component object or one of its parent containers.

The search order for resources is built around the containers that hold the component (if it is not a page). Consider a Page that contains a Panel that contains a Label. If we pass the Label as the component then resource loading will first look for the resource against the page, then against the panel and finally against the label.

The above search order may seem slightly odd at first, but can be explained thus: Team A writes a new component X and packages it as a reusable Wicket component along with all required resources. Team B then creates a new container component Y that holds a instance of an X. However, Team B wishes the text to be different to that which was provided with X so rather than needing to change X, they include override values in the resources for Y. Finally, Team C makes use of component Y in a page they are writing. Initially they are happy with the text for Y so they do not include any override values in the resources for the page. However, after demonstrating to the customer, the customer requests the text for Y to be different. Team C need only provide override values against their page and thus do not need to change Y.

This implementation is fully aware of both locale and style values when trying to obtain the appropriate resources.

In addition to the above search order, each key will be pre-pended with the relative path of the current component related to the component that is being searched. E.g. assume a component hierarchy like page1.form1.input1 and your are requesting a key named 'Required'. Wicket will search the property in the following order:

        page1.properties => form1.input1.Required
        page1.properties => Required
        form1.properties => input1.Required
        form1.properties => Required
        input1.properties => Required
        myApplication.properties => page1.form1.input1.Required
        myApplication.properties => Required
 

Note that the latter two property files are only checked if the ClassStringResourceLoader has been registered with Application as well, which is the default.

In addition to the above search order, each component that is being searched for a resource also includes the resources from any parent classes that it inherits from. For example, PageA extends CommonBasePage which in turn extends WebPage. When a resource lookup is requested on PageA, the resource bundle for PageA is first checked. If the resource is not found in this bundle then the resource bundle for CommonBasePage is checked. This allows designers of base pages and components to define default sets of string resources and then developers implementing subclasses to either override or extend these in their own resource bundle.

This implementation can be subclassed to implement modified behavior. The new implementation must be registered with the Application (ResourceSettings) though.

You may enable log debug messages for this class to fully understand the search order.

Author:

Chris Turner, Juergen Donnerstag

Constructor Summary

ComponentStringResourceLoader()
Create and initialize the resource loader.

Method Summary

protected boolean	isStopResourceSearch(java.lang.Class clazz) Check the supplied class to see if it is one that we shouldn't bother further searches up the class hierarchy for properties.
java.lang.String	loadStringResource(java.lang.Class clazz, java.lang.String key, java.util.Locale locale, java.lang.String style) Get the string resource for the given combination of class, key, locale and style.
java.lang.String	loadStringResource(Component component, java.lang.String key) Get the string resource for the given combination of component and resource key.

Methods inherited from class java.lang.Object

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

Constructor Detail

ComponentStringResourceLoader

public ComponentStringResourceLoader()

Create and initialize the resource loader.

Method Detail

loadStringResource

public java.lang.String loadStringResource(java.lang.Class clazz,
                                           java.lang.String key,
                                           java.util.Locale locale,
                                           java.lang.String style)

Get the string resource for the given combination of class, key, locale and style. The information is obtained from a resource bundle associated with the provided Class (or one of its super classes).

Specified by:

loadStringResource in interface IStringResourceLoader

Parameters:

clazz - The Class to find resources to be loaded

key - The key to obtain the string for

locale - The locale identifying the resource set to select the strings from

style - The (optional) style identifying the resource set to select the strings from (see Session)

Returns:

The string resource value or null if resource not found

loadStringResource

public java.lang.String loadStringResource(Component component,
                                           java.lang.String key)

Description copied from interface: IStringResourceLoader

Get the string resource for the given combination of component and resource key. The component provided is used to allow implementation of component specific resource loading (e.g. per page or per reusable component). The key should be a String containing a lookup key into a resource bundle. The Locale and the style will be taken from the Component provided.

Specified by:

loadStringResource in interface IStringResourceLoader

Parameters:

component - The component to get the string resource for

key - The key should be a String containing a lookup key into a resource bundle

Returns:

The string resource value or null if the resource could not be loaded by this loader

See Also:

IStringResourceLoader.loadStringResource(org.apache.wicket.Component, java.lang.String)

isStopResourceSearch

protected boolean isStopResourceSearch(java.lang.Class clazz)

Check the supplied class to see if it is one that we shouldn't bother further searches up the class hierarchy for properties.

Parameters:

clazz - The class to check

Returns:

Whether to stop the search