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The Apache Log4j Implementation
/*
* 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 org.apache.logging.log4j.core.config.plugins.convert;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Collection;
import java.util.Map;
import java.util.Objects;
import java.util.UnknownFormatConversionException;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import org.apache.logging.log4j.Logger;
import org.apache.logging.log4j.core.config.plugins.util.PluginManager;
import org.apache.logging.log4j.core.config.plugins.util.PluginType;
import org.apache.logging.log4j.core.util.ReflectionUtil;
import org.apache.logging.log4j.core.util.TypeUtil;
import org.apache.logging.log4j.status.StatusLogger;
/**
* Registry for {@link TypeConverter} plugins.
*
* @since 2.1
*/
public class TypeConverterRegistry {
private static final Logger LOGGER = StatusLogger.getLogger();
private static volatile TypeConverterRegistry INSTANCE;
private static final Object INSTANCE_LOCK = new Object();
private final ConcurrentMap> registry = new ConcurrentHashMap<>();
/**
* Gets the singleton instance of the TypeConverterRegistry.
*
* @return the singleton instance.
*/
public static TypeConverterRegistry getInstance() {
TypeConverterRegistry result = INSTANCE;
if (result == null) {
synchronized (INSTANCE_LOCK) {
result = INSTANCE;
if (result == null) {
INSTANCE = result = new TypeConverterRegistry();
}
}
}
return result;
}
/**
* Finds a {@link TypeConverter} for the given {@link Type}, falling back to an assignment-compatible TypeConverter
* if none exist for the given type. That is, if the given Type does not have a TypeConverter, but another Type
* which can be assigned to the given Type does have a TypeConverter, then that TypeConverter will be
* used and registered.
*
* @param type the Type to find a TypeConverter for (must not be {@code null}).
* @return a TypeConverter for the given Type.
* @throws UnknownFormatConversionException if no TypeConverter can be found for the given type.
*/
public TypeConverter findCompatibleConverter(final Type type) {
Objects.requireNonNull(type, "No type was provided");
final TypeConverter primary = registry.get(type);
// cached type converters
if (primary != null) {
return primary;
}
// dynamic enum support
if (type instanceof Class) {
final Class clazz = (Class) type;
if (clazz.isEnum()) {
@SuppressWarnings({"unchecked","rawtypes"})
final EnumConverter converter = new EnumConverter(clazz.asSubclass(Enum.class));
registry.putIfAbsent(type, converter);
return converter;
}
}
// look for compatible converters
for (final Map.Entry> entry : registry.entrySet()) {
final Type key = entry.getKey();
if (TypeUtil.isAssignable(type, key)) {
LOGGER.debug("Found compatible TypeConverter<{}> for type [{}].", key, type);
final TypeConverter value = entry.getValue();
registry.putIfAbsent(type, value);
return value;
}
}
throw new UnknownFormatConversionException(type.toString());
}
private TypeConverterRegistry() {
LOGGER.trace("TypeConverterRegistry initializing.");
final PluginManager manager = new PluginManager(TypeConverters.CATEGORY);
manager.collectPlugins();
loadKnownTypeConverters(manager.getPlugins().values());
registerPrimitiveTypes();
}
private void loadKnownTypeConverters(final Collection> knownTypes) {
for (final PluginType knownType : knownTypes) {
final Class clazz = knownType.getPluginClass();
if (TypeConverter.class.isAssignableFrom(clazz)) {
@SuppressWarnings("rawtypes")
final Class pluginClass = clazz.asSubclass(TypeConverter.class);
final Type conversionType = getTypeConverterSupportedType(pluginClass);
final TypeConverter converter = ReflectionUtil.instantiate(pluginClass);
if (registry.putIfAbsent(conversionType, converter) != null) {
LOGGER.warn("Found a TypeConverter [{}] for type [{}] that already exists.", converter,
conversionType);
}
}
}
}
private static Type getTypeConverterSupportedType(@SuppressWarnings("rawtypes") final Class typeConverterClass) {
for (final Type type : typeConverterClass.getGenericInterfaces()) {
if (type instanceof ParameterizedType) {
final ParameterizedType pType = (ParameterizedType) type;
if (TypeConverter.class.equals(pType.getRawType())) {
// TypeConverter has only one type argument (T), so return that
return pType.getActualTypeArguments()[0];
}
}
}
return Void.TYPE;
}
private void registerPrimitiveTypes() {
registerTypeAlias(Boolean.class, Boolean.TYPE);
registerTypeAlias(Byte.class, Byte.TYPE);
registerTypeAlias(Character.class, Character.TYPE);
registerTypeAlias(Double.class, Double.TYPE);
registerTypeAlias(Float.class, Float.TYPE);
registerTypeAlias(Integer.class, Integer.TYPE);
registerTypeAlias(Long.class, Long.TYPE);
registerTypeAlias(Short.class, Short.TYPE);
}
private void registerTypeAlias(final Type knownType, final Type aliasType) {
registry.putIfAbsent(aliasType, registry.get(knownType));
}
}