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package org.apache.velocity.util.introspection;
/*
* 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.
*/
import org.slf4j.Logger;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* A cache of introspection information for a specific class instance.
* Keys {@link java.lang.reflect.Field} objects by the field names.
*
* @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a>
* @author <a href="mailto:bob@werken.com">Bob McWhirter</a>
* @author <a href="mailto:szegedia@freemail.hu">Attila Szegedi</a>
* @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a>
* @author <a href="mailto:henning@apache.org">Henning P. Schmiedehausen</a>
* @author Nathan Bubna
* @author <a href="mailto:cdauth@cdauth.eu">Candid Dauth</a>
*/
public class ClassFieldMap
{
/** Set true if you want to debug the reflection code */
private static final boolean debugReflection = false;
/** Class logger */
private final Logger log;
/**
* Class passed into the constructor used to as
* the basis for the Field map.
*/
private final Class<?> clazz;
/**
* String --> Field map, the key is the field name
*/
private final Map<String, Field> fieldCache;
/**
* Standard constructor
* @param clazz The class for which this ClassMap gets constructed.
* @param log logger
*/
public ClassFieldMap(final Class<?> clazz, final Logger log)
{
this.clazz = clazz;
this.log = log;
if (debugReflection)
{
log.debug("=================================================================");
log.debug("== Class: {}", clazz);
}
fieldCache = createFieldCache();
if (debugReflection)
{
log.debug("=================================================================");
}
}
/**
* Returns the class object whose fields are cached by this map.
*
* @return The class object whose fields are cached by this map.
*/
public Class<?> getCachedClass()
{
return clazz;
}
/**
* Find a Field using the field name.
*
* @param name The field name to look up.
* @return A Field object representing the field to invoke or null.
*/
public Field findField(final String name)
{
return fieldCache.get(name);
}
/**
* Populate the Map of direct hits. These
* are taken from all the public fields
* that our class, its parents and their implemented interfaces provide.
*/
private Map<String, Field> createFieldCache()
{
Map<String, Field> fieldCache = new ConcurrentHashMap<>();
//
// Looks through all elements in the class hierarchy.
//
// We ignore all SecurityExceptions that might happen due to SecurityManager restrictions (prominently
// hit with Tomcat 5.5).
// Ah, the miracles of Java for(;;) ...
for (Class<?> classToReflect = getCachedClass(); classToReflect != null ; classToReflect = classToReflect.getSuperclass())
{
if (Modifier.isPublic(classToReflect.getModifiers()))
{
populateFieldCacheWith(fieldCache, classToReflect);
}
Class<?> [] interfaces = classToReflect.getInterfaces();
for (Class<?> anInterface : interfaces)
{
populateFieldCacheWithInterface(fieldCache, anInterface);
}
}
// return the already initialized cache
return fieldCache;
}
/* recurses up interface hierarchy to get all super interfaces (VELOCITY-689) */
private void populateFieldCacheWithInterface(Map<String, Field> fieldCache, Class<?> iface)
{
if (Modifier.isPublic(iface.getModifiers()))
{
populateFieldCacheWith(fieldCache, iface);
}
Class<?>[] supers = iface.getInterfaces();
for (Class<?> aSuper : supers)
{
populateFieldCacheWithInterface(fieldCache, aSuper);
}
}
private void populateFieldCacheWith(Map<String, Field> fieldCache, Class<?> classToReflect)
{
if (debugReflection)
{
log.debug("Reflecting {}", classToReflect);
}
try
{
Field[] fields = classToReflect.getDeclaredFields();
for (Field field : fields)
{
int modifiers = field.getModifiers();
if (Modifier.isPublic(modifiers))
{
fieldCache.put(field.getName(), field);
}
}
}
catch (SecurityException se) // Everybody feels better with...
{
log.debug("While accessing fields of {}:", classToReflect, se);
}
}
}
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