javax.el.ResourceBundleELResolver Maven / Gradle / Ivy
/*
* Copyright (c) 1997-2018 Oracle and/or its affiliates and others.
* All rights reserved.
* Copyright 2004 The Apache Software Foundation
*
* Licensed 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 javax.el;
import static java.lang.Boolean.TRUE;
import java.beans.FeatureDescriptor;
import java.util.ArrayList;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.List;
import java.util.MissingResourceException;
import java.util.ResourceBundle;
/**
* Defines property resolution behavior on instances of {@link java.util.ResourceBundle}.
*
*
* This resolver handles base objects of type java.util.ResourceBundle. It accepts any object as a property
* and coerces it to a java.lang.String for invoking
* {@link java.util.ResourceBundle#getObject(java.lang.String)}.
*
*
* This resolver is read only and will throw a {@link PropertyNotWritableException} if setValue is called.
*
*
* ELResolvers are combined together using {@link CompositeELResolver}s, to define rich semantics for
* evaluating an expression. See the javadocs for {@link ELResolver} for details.
*
* @see CompositeELResolver
* @see ELResolver
* @see java.util.ResourceBundle
*
* @since Jakarta Server Pages 2.1
*/
public class ResourceBundleELResolver extends ELResolver {
/**
* If the base object is an instance of ResourceBundle, the provided property will first be coerced to a
* String. The Object returned by getObject on the base
* ResourceBundle will be returned.
*
*
* If the base is ResourceBundle, the propertyResolved property of the ELContext
* object must be set to true by this resolver, before returning. If this property is not true
* after this method is called, the caller should ignore the return value.
*
* @param context The context of this evaluation.
* @param base The ResourceBundle to analyze.
* @param property The name of the property to analyze. Will be coerced to a String.
* @return If the propertyResolved property of ELContext was set to true, then
* null if property is null; otherwise the Object for the given key (property
* coerced to String) from the ResourceBundle. If no object for the given key can be found,
* then the String "???" + key + "???".
* @throws NullPointerException if context is null
* @throws ELException if an exception was thrown while performing the property or variable resolution. The thrown
* exception must be included as the cause property of this exception, if available.
*/
@Override
public Object getValue(ELContext context, Object base, Object property) {
if (context == null) {
throw new NullPointerException();
}
if (base instanceof ResourceBundle) {
context.setPropertyResolved(true);
if (property != null) {
try {
return ((ResourceBundle) base).getObject(property.toString());
} catch (MissingResourceException e) {
return "???" + property + "???";
}
}
}
return null;
}
/**
* If the base object is an instance of ResourceBundle, return null, since the resolver is
* read only.
*
*
* If the base is ResourceBundle, the propertyResolved property of the ELContext
* object must be set to true by this resolver, before returning. If this property is not true
* after this method is called, the caller should ignore the return value.
*
*
* @param context The context of this evaluation.
* @param base The ResourceBundle to analyze.
* @param property The name of the property to analyze.
* @return If the propertyResolved property of ELContext was set to true, then
* null; otherwise undefined.
* @throws NullPointerException if context is null
*/
@Override
public Class getType(ELContext context, Object base, Object property) {
if (context == null) {
throw new NullPointerException();
}
if (base instanceof ResourceBundle) {
context.setPropertyResolved(true);
}
return null;
}
/**
* If the base object is a ResourceBundle, throw a {@link PropertyNotWritableException}.
*
* @param context The context of this evaluation.
* @param base The ResourceBundle to be modified. Only bases that are of type ResourceBundle are handled.
* @param property The String property to use.
* @param value The value to be set.
* @throws NullPointerException if context is null.
* @throws PropertyNotWritableException Always thrown if base is an instance of ReasourceBundle.
*/
@Override
public void setValue(ELContext context, Object base, Object property, Object value) {
if (context == null) {
throw new NullPointerException();
}
if (base instanceof ResourceBundle) {
context.setPropertyResolved(true);
throw new PropertyNotWritableException("ResourceBundles are immutable");
}
}
/**
* If the base object is not null and an instanceof {@link ResourceBundle}, return true.
*
* @param context The context of this evaluation.
* @param base The ResourceBundle to be modified. Only bases that are of type ResourceBundle are handled.
* @param property The String property to use.
* @return If the propertyResolved property of ELContext was set to true, then
* true; otherwise undefined.
* @throws NullPointerException if context is null
*/
@Override
public boolean isReadOnly(ELContext context, Object base, Object property) {
if (context == null) {
throw new NullPointerException();
}
if (base instanceof ResourceBundle) {
context.setPropertyResolved(true);
return true;
}
return false;
}
/**
* If the base object is a ResourceBundle, returns an Iterator containing the set of keys available in the
* ResourceBundle. Otherwise, returns null.
*
*
* The Iterator returned must contain zero or more instances of {@link java.beans.FeatureDescriptor}. Each
* info object contains information about a key in the ResourceBundle, and is initialized as follows:
*
* - displayName - The
String key
* - name - Same as displayName property.
* - shortDescription - Empty string
* - expert -
false
* - hidden -
false
* - preferred -
true
*
*
* In addition, the following named attributes must be set in the returned FeatureDescriptors:
*
* - {@link ELResolver#TYPE} -
String.class
* - {@link ELResolver#RESOLVABLE_AT_DESIGN_TIME} -
true
*
*
*
* @param context The context of this evaluation.
* @param base The bundle whose keys are to be iterated over. Only bases of type ResourceBundle are handled
* by this resolver.
* @return An Iterator containing zero or more (possibly infinitely more) FeatureDescriptor
* objects, each representing a key in this bundle, or null if the base object is not a ResourceBundle.
*/
@Override
public Iterator getFeatureDescriptors(ELContext context, Object base) {
if (base instanceof ResourceBundle) {
ResourceBundle bundle = (ResourceBundle) base;
List features = new ArrayList<>();
String key = null;
FeatureDescriptor desc = null;
for (Enumeration e = bundle.getKeys(); e.hasMoreElements();) {
key = e.nextElement();
desc = new FeatureDescriptor();
desc.setDisplayName(key);
desc.setExpert(false);
desc.setHidden(false);
desc.setName(key);
desc.setPreferred(true);
desc.setValue(TYPE, String.class);
desc.setValue(RESOLVABLE_AT_DESIGN_TIME, TRUE);
features.add(desc);
}
return features.iterator();
}
return null;
}
/**
* If the base object is a ResourceBundle, returns the most general type that this resolver accepts for the
* property argument. Otherwise, returns null.
*
*
* Assuming the base is a ResourceBundle, this method will always return String.class.
*
* @param context The context of this evaluation.
* @param base The bundle to analyze. Only bases of type ResourceBundle are handled by this resolver.
* @return null if base is not a ResourceBundle; otherwise String.class.
*/
@Override
public Class getCommonPropertyType(ELContext context, Object base) {
if (base instanceof ResourceBundle) {
return String.class;
}
return null;
}
}