ResourceBundle.Control (Java SE 9 & JDK 9 ) (original) (raw)

public static class ResourceBundle.Control
extends Object
ResourceBundle.Control defines a set of callback methods that are invoked by the ResourceBundle.getBundle factory methods during the bundle loading process. In other words, aResourceBundle.Control collaborates with the factory methods for loading resource bundles. The default implementation of the callback methods provides the information necessary for the factory methods to perform the default behavior.Note that this class is not supported in named modules.
In addition to the callback methods, the toBundleName and toResourceName methods are defined primarily for convenience in implementing the callback methods. However, the toBundleName method could be overridden to provide different conventions in the organization and packaging of localized resources. The toResourceName method is final to avoid use of wrong resource and class name separators.
Two factory methods, getControl(List) and getNoFallbackControl(List), provideResourceBundle.Control instances that implement common variations of the default bundle loading process.
The formats returned by the getFormats method and candidate locales returned by the getCandidateLocales method must be consistent in allResourceBundle.getBundle invocations for the same base bundle. Otherwise, the ResourceBundle.getBundle methods may return unintended bundles. For example, if only"java.class" is returned by the getFormats method for the first call to ResourceBundle.getBundle and only "java.properties" for the second call, then the second call will return the class-based one that has been cached during the first call.
A ResourceBundle.Control instance must be thread-safe if it's simultaneously used by multiple threads.ResourceBundle.getBundle does not synchronize to call the ResourceBundle.Control methods. The default implementations of the methods are thread-safe.
Applications can specify ResourceBundle.Control instances returned by the getControl factory methods or created from a subclass of ResourceBundle.Control to customize the bundle loading process. The following are examples of changing the default bundle loading process.
Example 1
The following code lets ResourceBundle.getBundle look up only properties-based resources.
import java.util.;
import static java.util.ResourceBundle.Control.;
...
ResourceBundle bundle =
ResourceBundle.getBundle("MyResources", new Locale("fr", "CH"),
ResourceBundle.Control.getControl(FORMAT_PROPERTIES));

Given the resource bundles in the example in the ResourceBundle.getBundle description, thisResourceBundle.getBundle call loadsMyResources_fr_CH.properties whose parent isMyResources_fr.properties whose parent isMyResources.properties. (MyResources_fr_CH.properties is not hidden, but MyResources_fr_CH.class is.)
Example 2
The following is an example of loading XML-based bundles using Properties.loadFromXML.
ResourceBundle rb = ResourceBundle.getBundle("Messages",
new ResourceBundle.Control() {
public List getFormats(String baseName) {
if (baseName == null)
throw new NullPointerException();
return Arrays.asList("xml");
}
public ResourceBundle newBundle(String baseName,
Locale locale,
String format,
ClassLoader loader,
boolean reload)
throws IllegalAccessException,
InstantiationException,
IOException {
if (baseName == null || locale == null
|| format == null || loader == null)
throw new NullPointerException();
ResourceBundle bundle = null;
if (format.equals("xml")) {
String bundleName = toBundleName(baseName, locale);
String resourceName = toResourceName(bundleName, format);
InputStream stream = null;
if (reload) {
URL url = loader.getResource(resourceName);
if (url != null) {
URLConnection connection = url.openConnection();
if (connection != null) {
// Disable caches to get fresh data for
// reloading.
connection.setUseCaches(false);
stream = connection.getInputStream();
}
}
} else {
stream = loader.getResourceAsStream(resourceName);
}
if (stream != null) {
BufferedInputStream bis = new BufferedInputStream(stream);
bundle = new XMLResourceBundle(bis);
bis.close();
}
}
return bundle;
}
});
...
private static class XMLResourceBundle extends ResourceBundle {
private Properties props;
XMLResourceBundle(InputStream stream) throws IOException {
props = new Properties();
props.loadFromXML(stream);
}
protected Object handleGetObject(String key) {
return props.getProperty(key);
}
public Enumeration getKeys() {
...
}
}

API Note:
ResourceBundle.Control is not supported in named modules. If the ResourceBundle.getBundle method with a ResourceBundle.Control is called in a named module, the method will throw an UnsupportedOperationException. Any service providers of ResourceBundleControlProvider are ignored in named modules.
Since:
1.6
See Also:
ResourceBundleProvider