Java tutorial
/* * 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 javax.el; 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.Objects; import java.util.ResourceBundle; public class ResourceBundleELResolver extends ELResolver { public ResourceBundleELResolver() { super(); } @Override public Object getValue(ELContext context, Object base, Object property) { Objects.requireNonNull(context); if (base instanceof ResourceBundle) { context.setPropertyResolved(base, property); if (property != null) { try { return ((ResourceBundle) base).getObject(property.toString()); } catch (MissingResourceException mre) { return "???" + property.toString() + "???"; } } } return null; } @Override public Class<?> getType(ELContext context, Object base, Object property) { Objects.requireNonNull(context); if (base instanceof ResourceBundle) { context.setPropertyResolved(base, property); } return null; } @Override public void setValue(ELContext context, Object base, Object property, Object value) { Objects.requireNonNull(context); if (base instanceof ResourceBundle) { context.setPropertyResolved(base, property); throw new PropertyNotWritableException( Util.message(context, "resolverNotWriteable", base.getClass().getName())); } } @Override public boolean isReadOnly(ELContext context, Object base, Object property) { Objects.requireNonNull(context); if (base instanceof ResourceBundle) { context.setPropertyResolved(base, property); return true; } return false; } @Override public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) { if (base instanceof ResourceBundle) { List<FeatureDescriptor> feats = new ArrayList<>(); Enumeration<String> e = ((ResourceBundle) base).getKeys(); FeatureDescriptor feat; String key; while (e.hasMoreElements()) { key = e.nextElement(); feat = new FeatureDescriptor(); feat.setDisplayName(key); feat.setShortDescription(""); feat.setExpert(false); feat.setHidden(false); feat.setName(key); feat.setPreferred(true); feat.setValue(RESOLVABLE_AT_DESIGN_TIME, Boolean.TRUE); feat.setValue(TYPE, String.class); feats.add(feat); } return feats.iterator(); } return null; } @Override public Class<?> getCommonPropertyType(ELContext context, Object base) { if (base instanceof ResourceBundle) { return String.class; } return null; } }