/*
* Copyright 2002-2012 the original author or authors.
*
* 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.springframework.core;
import java.util.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.HashSet;
import java.util.IdentityHashMap;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.TreeMap;
import java.util.TreeSet;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.CopyOnWriteArraySet;
import org.springframework.util.ClassUtils;
import org.springframework.util.LinkedCaseInsensitiveMap;
import org.springframework.util.LinkedMultiValueMap;
import org.springframework.util.MultiValueMap;
/**
* Factory for collections, being aware of Java 5 and Java 6 collections.
* Mainly for internal use within the framework.
*
* <p>The goal of this class is to avoid runtime dependencies on a specific
* Java version, while nevertheless using the best collection implementation
* that is available at runtime.
*
* @author Juergen Hoeller
* @author Arjen Poutsma
* @since 2.0
*/
public abstract class CollectionFactory {
private static Class navigableSetClass = null;
private static Class navigableMapClass = null;
private static final Set<Class> approximableCollectionTypes = new HashSet<Class>(10);
private static final Set<Class> approximableMapTypes = new HashSet<Class>(6);
static {
// Standard collection interfaces
approximableCollectionTypes.add(Collection.class);
approximableCollectionTypes.add(List.class);
approximableCollectionTypes.add(Set.class);
approximableCollectionTypes.add(SortedSet.class);
approximableMapTypes.add(Map.class);
approximableMapTypes.add(SortedMap.class);
// New Java 6 collection interfaces
ClassLoader cl = CollectionFactory.class.getClassLoader();
try {
navigableSetClass = ClassUtils.forName("java.util.NavigableSet", cl);
navigableMapClass = ClassUtils.forName("java.util.NavigableMap", cl);
approximableCollectionTypes.add(navigableSetClass);
approximableMapTypes.add(navigableMapClass);
}
catch (ClassNotFoundException ex) {
// not running on Java 6 or above...
}
// Common concrete collection classes
approximableCollectionTypes.add(ArrayList.class);
approximableCollectionTypes.add(LinkedList.class);
approximableCollectionTypes.add(HashSet.class);
approximableCollectionTypes.add(LinkedHashSet.class);
approximableCollectionTypes.add(TreeSet.class);
approximableMapTypes.add(HashMap.class);
approximableMapTypes.add(LinkedHashMap.class);
approximableMapTypes.add(TreeMap.class);
}
/**
* Create a linked Set if possible: This implementation always
* creates a {@link java.util.LinkedHashSet}.
* @param initialCapacity the initial capacity of the Set
* @return the new Set instance
* @deprecated
*/
@Deprecated
public static <T> Set<T> createLinkedSetIfPossible(int initialCapacity) {
return new LinkedHashSet<T>(initialCapacity);
}
/**
* Create a copy-on-write Set (allowing for synchronization-less iteration) if possible:
* This implementation always creates a {@link java.util.concurrent.CopyOnWriteArraySet}.
* @return the new Set instance
* @deprecated
*/
@Deprecated
public static <T> Set<T> createCopyOnWriteSet() {
return new CopyOnWriteArraySet<T>();
}
/**
* Create a linked Map if possible: This implementation always
* creates a {@link java.util.LinkedHashMap}.
* @param initialCapacity the initial capacity of the Map
* @return the new Map instance
* @deprecated
*/
@Deprecated
public static <K,V> Map<K,V> createLinkedMapIfPossible(int initialCapacity) {
return new LinkedHashMap<K,V>(initialCapacity);
}
/**
* Create a linked case-insensitive Map if possible: This implementation
* always returns a {@link org.springframework.util.LinkedCaseInsensitiveMap}.
* @param initialCapacity the initial capacity of the Map
* @return the new Map instance
* @deprecated
*/
@Deprecated
public static Map createLinkedCaseInsensitiveMapIfPossible(int initialCapacity) {
return new LinkedCaseInsensitiveMap(initialCapacity);
}
/**
* Create an identity Map if possible: This implementation always
* creates a {@link java.util.IdentityHashMap}.
* @param initialCapacity the initial capacity of the Map
* @return the new Map instance
* @deprecated
*/
@Deprecated
public static Map createIdentityMapIfPossible(int initialCapacity) {
return new IdentityHashMap(initialCapacity);
}
/**
* Create a concurrent Map if possible: This implementation always
* creates a {@link java.util.concurrent.ConcurrentHashMap}.
* @param initialCapacity the initial capacity of the Map
* @return the new Map instance
* @deprecated
*/
@Deprecated
public static Map createConcurrentMapIfPossible(int initialCapacity) {
return new ConcurrentHashMap(initialCapacity);
}
/**
* Create a concurrent Map with a dedicated {@link ConcurrentMap} interface:
* This implementation always creates a {@link java.util.concurrent.ConcurrentHashMap}.
* @param initialCapacity the initial capacity of the Map
* @return the new ConcurrentMap instance
* @deprecated
*/
@Deprecated
public static ConcurrentMap createConcurrentMap(int initialCapacity) {
return new JdkConcurrentHashMap(initialCapacity);
}
/**
* Determine whether the given collection type is an approximable type,
* i.e. a type that {@link #createApproximateCollection} can approximate.
* @param collectionType the collection type to check
* @return {@code true} if the type is approximable,
* {@code false} if it is not
*/
public static boolean isApproximableCollectionType(Class<?> collectionType) {
return (collectionType != null && approximableCollectionTypes.contains(collectionType));
}
/**
* Create the most approximate collection for the given collection.
* <p>Creates an ArrayList, TreeSet or linked Set for a List, SortedSet
* or Set, respectively.
* @param collection the original Collection object
* @param initialCapacity the initial capacity
* @return the new Collection instance
* @see java.util.ArrayList
* @see java.util.TreeSet
* @see java.util.LinkedHashSet
*/
@SuppressWarnings("unchecked")
public static Collection createApproximateCollection(Object collection, int initialCapacity) {
if (collection instanceof LinkedList) {
return new LinkedList();
}
else if (collection instanceof List) {
return new ArrayList(initialCapacity);
}
else if (collection instanceof SortedSet) {
return new TreeSet(((SortedSet) collection).comparator());
}
else {
return new LinkedHashSet(initialCapacity);
}
}
/**
* Create the most appropriate collection for the given collection type.
* <p>Creates an ArrayList, TreeSet or linked Set for a List, SortedSet
* or Set, respectively.
* @param collectionType the desired type of the target Collection
* @param initialCapacity the initial capacity
* @return the new Collection instance
* @see java.util.ArrayList
* @see java.util.TreeSet
* @see java.util.LinkedHashSet
*/
public static Collection createCollection(Class<?> collectionType, int initialCapacity) {
if (collectionType.isInterface()) {
if (List.class.equals(collectionType)) {
return new ArrayList(initialCapacity);
}
else if (SortedSet.class.equals(collectionType) || collectionType.equals(navigableSetClass)) {
return new TreeSet();
}
else if (Set.class.equals(collectionType) || Collection.class.equals(collectionType)) {
return new LinkedHashSet(initialCapacity);
}
else {
throw new IllegalArgumentException("Unsupported Collection interface: " + collectionType.getName());
}
}
else {
if (!Collection.class.isAssignableFrom(collectionType)) {
throw new IllegalArgumentException("Unsupported Collection type: " + collectionType.getName());
}
try {
return (Collection) collectionType.newInstance();
}
catch (Exception ex) {
throw new IllegalArgumentException("Could not instantiate Collection type: " +
collectionType.getName(), ex);
}
}
}
/**
* Determine whether the given map type is an approximable type,
* i.e. a type that {@link #createApproximateMap} can approximate.
* @param mapType the map type to check
* @return {@code true} if the type is approximable,
* {@code false} if it is not
*/
public static boolean isApproximableMapType(Class<?> mapType) {
return (mapType != null && approximableMapTypes.contains(mapType));
}
/**
* Create the most approximate map for the given map.
* <p>Creates a TreeMap or linked Map for a SortedMap or Map, respectively.
* @param map the original Map object
* @param initialCapacity the initial capacity
* @return the new Map instance
* @see java.util.TreeMap
* @see java.util.LinkedHashMap
*/
@SuppressWarnings("unchecked")
public static Map createApproximateMap(Object map, int initialCapacity) {
if (map instanceof SortedMap) {
return new TreeMap(((SortedMap) map).comparator());
}
else {
return new LinkedHashMap(initialCapacity);
}
}
/**
* Create the most approximate map for the given map.
* <p>Creates a TreeMap or linked Map for a SortedMap or Map, respectively.
* @param mapType the desired type of the target Map
* @param initialCapacity the initial capacity
* @return the new Map instance
* @see java.util.TreeMap
* @see java.util.LinkedHashMap
*/
public static Map createMap(Class<?> mapType, int initialCapacity) {
if (mapType.isInterface()) {
if (Map.class.equals(mapType)) {
return new LinkedHashMap(initialCapacity);
}
else if (SortedMap.class.equals(mapType) || mapType.equals(navigableMapClass)) {
return new TreeMap();
}
else if (MultiValueMap.class.equals(mapType)) {
return new LinkedMultiValueMap();
}
else {
throw new IllegalArgumentException("Unsupported Map interface: " + mapType.getName());
}
}
else {
if (!Map.class.isAssignableFrom(mapType)) {
throw new IllegalArgumentException("Unsupported Map type: " + mapType.getName());
}
try {
return (Map) mapType.newInstance();
}
catch (Exception ex) {
throw new IllegalArgumentException("Could not instantiate Map type: " +
mapType.getName(), ex);
}
}
}
/**
* ConcurrentMap adapter for the JDK ConcurrentHashMap class.
*/
@Deprecated
@SuppressWarnings("serial")
private static class JdkConcurrentHashMap extends ConcurrentHashMap implements ConcurrentMap {
private JdkConcurrentHashMap(int initialCapacity) {
super(initialCapacity);
}
}
}