/*
* 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 jakarta.servlet.jsp.el;
import java.util.Objects;
import jakarta.el.ELClass;
import jakarta.el.ELContext;
import jakarta.el.ELResolver;
import jakarta.el.ImportHandler;
/**
* Providers resolution of imports and static imports in the Jakarta Pages ELResolver chain.
*
* @since JSP 3.1
*/
public class ImportELResolver extends ELResolver {
// Indicates if a performance short-cut is available
private static final Class<?> AST_IDENTIFIER_KEY;
static {
Class<?> key = null;
try {
key = Class.forName("org.apache.el.parser.AstIdentifier");
} catch (Exception e) {
// Ignore: Expected if not running on Tomcat. Not a problem since
// this just allows a short-cut.
}
AST_IDENTIFIER_KEY = key;
}
/**
* Default constructor.
*/
public ImportELResolver() {
super();
}
@Override
public Object getValue(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
Object result = null;
if (base == null) {
if (property != null) {
boolean resolveClass = true;
// Performance short-cut available when running on Tomcat
if (AST_IDENTIFIER_KEY != null) {
// Tomcat will set this key to Boolean.TRUE if the
// identifier is a stand-alone identifier (i.e.
// identifier) rather than part of an AstValue (i.e.
// identifier.something). Imports do not need to be
// checked if this is a stand-alone identifier
Boolean value = (Boolean) context.getContext(AST_IDENTIFIER_KEY);
if (value != null && value.booleanValue()) {
resolveClass = false;
}
}
ImportHandler importHandler = context.getImportHandler();
if (importHandler != null) {
String key = property.toString();
Class<?> clazz;
if (resolveClass) {
clazz = importHandler.resolveClass(key);
if (clazz != null) {
result = new ELClass(clazz);
}
}
if (result == null) {
// This might be the name of an imported static field
clazz = importHandler.resolveStatic(key);
if (clazz != null) {
try {
result = clazz.getField(key).get(null);
} catch (IllegalArgumentException | IllegalAccessException | NoSuchFieldException |
SecurityException e) {
// Most (all?) of these should have been
// prevented by the checks when the import
// was defined.
}
}
}
}
}
}
if (result != null) {
context.setPropertyResolved(base, property);
}
return result;
}
@Override
public Class<Object> getType(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
// In normal usage, ScopedAttributeELResolver will have responded.
return null;
}
@Override
public void setValue(ELContext context, Object base, Object property, Object value) {
Objects.requireNonNull(context);
// In normal usage, ScopedAttributeELResolver will have responded.
}
@Override
public boolean isReadOnly(ELContext context, Object base, Object property) {
Objects.requireNonNull(context);
// In normal usage, ScopedAttributeELResolver will have responded.
return false;
}
@Override
public Class<String> getCommonPropertyType(ELContext context, Object base) {
// In normal usage, ScopedAttributeELResolver will have responded.
return null;
}
}