/*
* Copyright 2008-2010 the T2 Project ant the Others.
*
* Licensed 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.t2framework.commons.util;
import java.lang.reflect.Array;
import java.lang.reflect.GenericArrayType;
import java.lang.reflect.GenericDeclaration;
import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.util.Collection;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
public class GenericsUtil {
public static Class getActualClass(Type type, Class targetClass) {
Map, Type> map = getTypeVariableMap(targetClass);
return getActualClass(type, map);
}
public static Type getActualType(Type type, Class targetClass) {
Map, Type> map = getTypeVariableMap(targetClass);
return getActualType(type, map);
}
private static Class getActualClass(Type type,
Map, Type> map) {
if (Class.class.isInstance(type)) {
return Class.class.cast(type);
}
if (ParameterizedType.class.isInstance(type)) {
final Type actualType = getActualType(type, map);
return getActualClass(actualType, map);
} else if (TypeVariable.class.isInstance(type)) {
final Type actualType = getActualType(type, map);
return getActualClass(actualType, map);
} else if (GenericArrayType.class.isInstance(type)) {
GenericArrayType genericArrayType = GenericArrayType.class
.cast(type);
final Type genericComponentType = genericArrayType
.getGenericComponentType();
Class componentClass = getActualClass(genericComponentType, map);
return Array.newInstance(componentClass, 0).getClass();
} else {
return null;
}
}
private static Type getActualType(Type type, Map, Type> map) {
if (Class.class.isInstance(type)) {
return type;
} else if (ParameterizedType.class.isInstance(type)) {
return ParameterizedType.class.cast(type).getRawType();
} else if (TypeVariable.class.isInstance(type)) {
return map.get(TypeVariable.class.cast(type));
} else {
return null;
}
}
private static Map, Type> getTypeVariableMap(
final Class clazz) {
if (clazz == null) {
return Collections.emptyMap();
}
final Map, Type> map = new LinkedHashMap, Type>();
final Class superClass = clazz.getSuperclass();
final Type superClassType = clazz.getGenericSuperclass();
if (superClass != null) {
gatherTypeVariables(superClass, superClassType, map);
}
final Class[] interfaces = clazz.getInterfaces();
final Type[] interfaceTypes = clazz.getGenericInterfaces();
for (int i = 0; i < interfaces.length; ++i) {
gatherTypeVariables(interfaces[i], interfaceTypes[i], map);
}
return map;
}
private static void gatherTypeVariables(final Class clazz,
final Type type, final Map, Type> map) {
if (clazz == null) {
return;
}
gatherTypeVariables(type, map);
final Class superClass = clazz.getSuperclass();
final Type superClassType = clazz.getGenericSuperclass();
if (superClass != null) {
gatherTypeVariables(superClass, superClassType, map);
}
final Class[] interfaces = clazz.getInterfaces();
final Type[] interfaceTypes = clazz.getGenericInterfaces();
for (int i = 0; i < interfaces.length; ++i) {
gatherTypeVariables(interfaces[i], interfaceTypes[i], map);
}
}
private static void gatherTypeVariables(final Type type,
final Map, Type> map) {
if (ParameterizedType.class.isInstance(type)) {
final ParameterizedType parameterizedType = ParameterizedType.class
.cast(type);
final TypeVariable[] typeVariables = GenericDeclaration.class
.cast(parameterizedType.getRawType()).getTypeParameters();
final Type[] actualTypes = parameterizedType
.getActualTypeArguments();
for (int i = 0; i < actualTypes.length; ++i) {
map.put(typeVariables[i], actualTypes[i]);
}
}
}
}