/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.wicket.resource.loader;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import org.apache.wicket.Application;
import org.apache.wicket.Component;
import org.apache.wicket.MarkupContainer;
import org.apache.wicket.Page;
import org.apache.wicket.markup.html.WebComponent;
import org.apache.wicket.markup.html.WebMarkupContainer;
import org.apache.wicket.markup.html.WebPage;
import org.apache.wicket.markup.repeater.AbstractRepeater;
import org.apache.wicket.resource.IPropertiesFactory;
import org.apache.wicket.resource.Properties;
import org.apache.wicket.util.lang.Args;
import org.apache.wicket.core.util.resource.locator.IResourceStreamLocator;
import org.apache.wicket.core.util.resource.locator.ResourceNameIterator;
import org.apache.wicket.util.string.Strings;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* This is one of Wicket's default string resource loaders.
* <p>
* 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.
* <p>
* 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.
* <p>
* 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.
* <p>
* This implementation is fully aware of both locale and style values when trying to obtain the
* appropriate resources.
* <p>
* 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:
*
* <pre>
* 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
* </pre>
*
* Note that the latter two property files are only checked if the ClassStringResourceLoader has
* been registered with Application as well, which is the default.
* <p>
* 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.
* <p>
* This implementation can be subclassed to implement modified behavior. The new implementation must
* be registered with the Application (ResourceSettings) though.
* <p>
* You may enable log debug messages for this class to fully understand the search order.
*
* @author Chris Turner
* @author Juergen Donnerstag
*/
public class ComponentStringResourceLoader implements IStringResourceLoader
{
/** Log. */
private static final Logger log = LoggerFactory.getLogger(ComponentStringResourceLoader.class);
/**
* Create and initialize the resource loader.
*/
public ComponentStringResourceLoader()
{
}
/**
* @see org.apache.wicket.resource.loader.IStringResourceLoader#loadStringResource(java.lang.Class,
* java.lang.String, java.util.Locale, java.lang.String, java.lang.String)
*/
@Override
public String loadStringResource(Class<?> clazz, final String key, final Locale locale,
final String style, final String variation)
{
if (clazz == null)
{
return null;
}
if (log.isDebugEnabled())
{
log.debug("key: '" + key + "'; class: '" + clazz.getName() + "'; locale: '" + locale +
"'; Style: '" + style + "'; Variation: '" + variation + '\'');
}
// Load the properties associated with the path
IPropertiesFactory propertiesFactory = getPropertiesFactory();
while (true)
{
// Create the base path
String path = clazz.getName().replace('.', '/');
// Iterator over all the combinations
ResourceNameIterator iter = newResourceNameIterator(path, locale, style, variation);
while (iter.hasNext())
{
String newPath = iter.next();
Properties props = propertiesFactory.load(clazz, newPath);
if (props != null)
{
// Lookup the value
String value = props.getString(key);
if (value != null)
{
return value;
}
}
}
// Didn't find the key yet, continue searching if possible
if (isStopResourceSearch(clazz))
{
break;
}
// Move to the next superclass
clazz = clazz.getSuperclass();
if (clazz == null)
{
// nothing more to search, done
break;
}
}
// not found
return null;
}
/**
* @see IResourceStreamLocator#newResourceNameIterator(String, Locale, String, String, String,
* boolean)
*
* @param path
* @param locale
* @param style
* @param variation
* @return resource name iterator
*/
protected ResourceNameIterator newResourceNameIterator(final String path, final Locale locale,
final String style, final String variation)
{
return Application.get()
.getResourceSettings()
.getResourceStreamLocator()
.newResourceNameIterator(path, locale, style, variation, null, false);
}
/**
* Get the properties file factory which loads the properties based on locale and style from
* *.properties and *.xml files
*
* @return properties factory
*/
protected IPropertiesFactory getPropertiesFactory()
{
return Application.get().getResourceSettings().getPropertiesFactory();
}
/**
* @see org.apache.wicket.resource.loader.IStringResourceLoader#loadStringResource(org.apache.wicket.Component,
* java.lang.String, java.util.Locale, java.lang.String, java.lang.String)
*/
@Override
public String loadStringResource(final Component component, final String key,
final Locale locale, final String style, final String variation)
{
if (component == null)
{
return null;
}
if (log.isDebugEnabled())
{
log.debug("component: '" + component.toString(false) + "'; key: '" + key + '\'');
}
// The return value
String string = null;
// The key prefix is equal to the component path relative to the
// current component on the top of the stack.
String prefix = getResourcePath(component);
// walk downwards starting with page going down to component
for (Component current : getComponentTrail(component))
{
// get current component class
final Class<?> clazz = current.getClass();
// first, try the fully qualified resource name relative to the
// component on the path from page down.
if (Strings.isEmpty(prefix) == false)
{
// lookup fully qualified path
string = loadStringResource(clazz, prefix + '.' + key, locale, style, variation);
// return string if we found it
if (string != null)
{
return string;
}
// shorten resource key prefix when going downwards (skip for repeaters)
if ((current instanceof AbstractRepeater) == false)
{
prefix = Strings.afterFirst(prefix, '.');
}
}
// If not found, than check if a property with the 'key' provided by
// the user can be found.
string = loadStringResource(clazz, key, locale, style, variation);
// return string if we found it
if (string != null)
{
return string;
}
}
return string;
}
/**
* get path for resource lookup
*
* @param component
* @return path
*/
protected String getResourcePath(final Component component)
{
Component current = Args.notNull(component, "component");
final StringBuilder buffer = new StringBuilder();
while (current.getParent() != null)
{
final boolean skip = current.getParent() instanceof AbstractRepeater;
if (skip == false)
{
if (buffer.length() > 0)
{
buffer.insert(0, '.');
}
buffer.insert(0, current.getId());
}
current = current.getParent();
}
return buffer.toString();
}
/**
* return the trail of components from page to specified component
*
* @param component
* The component to retrieve path for
* @return The list of components starting from top going down to component
*/
private List<Component> getComponentTrail(Component component)
{
final List<Component> path = new ArrayList<Component>();
while (component != null)
{
path.add(0, component);
component = component.getParent();
}
return path;
}
/**
* Check the supplied class to see if it is one that we shouldn't bother further searches up the
* class hierarchy for properties.
*
* @param clazz
* The class to check
* @return Whether to stop the search
*/
protected boolean isStopResourceSearch(final Class<?> clazz)
{
if ((clazz == null) || clazz.equals(Object.class) || clazz.equals(Application.class))
{
return true;
}
// Stop at all html markup base classes
if (clazz.equals(WebPage.class) || clazz.equals(WebMarkupContainer.class) ||
clazz.equals(WebComponent.class))
{
return true;
}
// Stop at all wicket base classes
return clazz.equals(Page.class) || clazz.equals(MarkupContainer.class) ||
clazz.equals(Component.class);
}
}