/*
* 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.lang.reflect.Field;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* @since EL 3.0
*/
public class ImportHandler {
private List<String> packageNames = new ArrayList<>();
private Map<String,String> classNames = new ConcurrentHashMap<>();
private Map<String,Class<?>> clazzes = new ConcurrentHashMap<>();
private Map<String,Class<?>> statics = new ConcurrentHashMap<>();
public ImportHandler() {
importPackage("java.lang");
}
public void importStatic(String name) throws javax.el.ELException {
int lastPeriod = name.lastIndexOf('.');
if (lastPeriod < 0) {
throw new ELException(Util.message(
null, "importHandler.invalidStaticName", name));
}
String className = name.substring(0, lastPeriod);
String fieldOrMethodName = name.substring(lastPeriod + 1);
Class<?> clazz = findClass(className, true);
if (clazz == null) {
throw new ELException(Util.message(
null, "importHandler.invalidClassNameForStatic",
className, name));
}
boolean found = false;
for (Field field : clazz.getFields()) {
if (field.getName().equals(fieldOrMethodName)) {
int modifiers = field.getModifiers();
if (Modifier.isStatic(modifiers) &&
Modifier.isPublic(modifiers)) {
found = true;
break;
}
}
}
if (!found) {
for (Method method : clazz.getMethods()) {
if (method.getName().equals(fieldOrMethodName)) {
int modifiers = method.getModifiers();
if (Modifier.isStatic(modifiers) &&
Modifier.isPublic(modifiers)) {
found = true;
break;
}
}
}
}
if (!found) {
throw new ELException(Util.message(null,
"importHandler.staticNotFound", fieldOrMethodName,
className, name));
}
Class<?> conflict = statics.get(fieldOrMethodName);
if (conflict != null) {
throw new ELException(Util.message(null,
"importHandler.ambiguousStaticImport", name,
conflict.getName() + '.' + fieldOrMethodName));
}
statics.put(fieldOrMethodName, clazz);
}
public void importClass(String name) throws javax.el.ELException {
int lastPeriodIndex = name.lastIndexOf('.');
if (lastPeriodIndex < 0) {
throw new ELException(Util.message(
null, "importHandler.invalidClassName", name));
}
String unqualifiedName = name.substring(lastPeriodIndex + 1);
String currentName = classNames.putIfAbsent(unqualifiedName, name);
if (currentName != null && !currentName.equals(name)) {
// Conflict. Same unqualifiedName, different fully qualified names
throw new ELException(Util.message(null,
"importHandler.ambiguousImport", name, currentName));
}
}
public void importPackage(String name) {
// Import ambiguity is handled at resolution, not at import
// Whether the package exists is not checked,
// a) for sake of performance when used in JSPs (BZ 57142),
// b) java.lang.Package.getPackage(name) is not reliable (BZ 57574),
// c) such check is not required by specification.
packageNames.add(name);
}
public java.lang.Class<?> resolveClass(String name) {
if (name == null || name.contains(".")) {
return null;
}
// Has it been previously resolved?
Class<?> result = clazzes.get(name);
if (result != null) {
if (NotFound.class.equals(result)) {
return null;
} else {
return result;
}
}
// Search the class imports
String className = classNames.get(name);
if (className != null) {
Class<?> clazz = findClass(className, true);
if (clazz != null) {
clazzes.put(name, clazz);
return clazz;
}
}
// Search the package imports - note there may be multiple matches
// (which correctly triggers an error)
for (String p : packageNames) {
className = p + '.' + name;
Class<?> clazz = findClass(className, false);
if (clazz != null) {
if (result != null) {
throw new ELException(Util.message(null,
"importHandler.ambiguousImport", className,
result.getName()));
}
result = clazz;
}
}
if (result == null) {
// Cache NotFound results to save repeated calls to findClass()
// which is relatively slow
clazzes.put(name, NotFound.class);
} else {
clazzes.put(name, result);
}
return result;
}
public java.lang.Class<?> resolveStatic(String name) {
return statics.get(name);
}
private Class<?> findClass(String name, boolean throwException) {
Class<?> clazz;
ClassLoader cl = Thread.currentThread().getContextClassLoader();
String path = name.replace('.', '/') + ".class";
try {
/* Given that findClass() has to be called for every imported
* package and that getResource() is a lot faster then loadClass()
* for resources that don't exist, the overhead of the getResource()
* for the case where the class does exist is a lot less than the
* overhead we save by not calling loadClass().
*/
if (cl.getResource(path) == null) {
return null;
}
} catch (ClassCircularityError cce) {
// May happen under a security manager. Ignore it and try loading
// the class normally.
}
try {
clazz = cl.loadClass(name);
} catch (ClassNotFoundException e) {
return null;
}
// Class must be public, non-abstract and not an interface
int modifiers = clazz.getModifiers();
if (!Modifier.isPublic(modifiers) || Modifier.isAbstract(modifiers) ||
Modifier.isInterface(modifiers)) {
if (throwException) {
throw new ELException(Util.message(
null, "importHandler.invalidClass", name));
} else {
return null;
}
}
return clazz;
}
/*
* Marker class used because null values are not permitted in a
* ConcurrentHashMap.
*/
private static class NotFound {
}
}