org.springframework.core.CollectionFactory Maven / Gradle / Ivy
/*
* Copyright 2002-2007 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.Collections;
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.NavigableMap;
import java.util.NavigableSet;
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.apache.commons.collections.map.CaseInsensitiveMap;
import org.apache.commons.collections.map.ListOrderedMap;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.util.ClassUtils;
/**
* Factory for collections, being aware of Commons Collection 3.x's extended
* collections as well as of JDK 1.5+ concurrent collections and backport-concurrent
* collections. Mainly for internal use within the framework.
*
* The goal of this class is to avoid runtime dependencies on JDK 1.5+ and
* Commons Collections 3.x, simply using the best collection implementation
* that is available at runtime. As of Spring 2.5, JDK 1.4 is required,
* so former adapter methods for JDK 1.3/1.4 always return the JDK 1.4
* collections now. The adapter methods are still kept for supporting
* Spring-based applications/frameworks which were built to support JDK 1.3.
*
* @author Juergen Hoeller
* @since 1.1.1
*/
public abstract class CollectionFactory {
private static final Log logger = LogFactory.getLog(CollectionFactory.class);
/** Whether the Commons Collections 3.x library is present on the classpath */
private static final boolean commonsCollections3Available =
ClassUtils.isPresent("org.apache.commons.collections.map.CaseInsensitiveMap",
CollectionFactory.class.getClassLoader());
/** Whether the backport-concurrent library is present on the classpath */
private static final boolean backportConcurrentAvailable =
ClassUtils.isPresent("edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap",
CollectionFactory.class.getClassLoader());
private static final Set approximableCollectionTypes = new HashSet(10);
private static final Set approximableMapTypes = new HashSet(6);
static {
approximableCollectionTypes.add(Collection.class);
approximableCollectionTypes.add(List.class);
approximableCollectionTypes.add(Set.class);
approximableCollectionTypes.add(SortedSet.class);
approximableMapTypes.add(Map.class);
approximableMapTypes.add(SortedMap.class);
if (JdkVersion.isAtLeastJava16()) {
approximableCollectionTypes.add(NavigableSet.class);
approximableMapTypes.add(NavigableMap.class);
}
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}, since Spring 2.5
* requires JDK 1.4 anyway.
* @param initialCapacity the initial capacity of the Set
* @return the new Set instance
* @deprecated as of Spring 2.5, for usage on JDK 1.4 or higher
*/
public static Set createLinkedSetIfPossible(int initialCapacity) {
return new LinkedHashSet(initialCapacity);
}
/**
* Create a copy-on-write Set (allowing for synchronization-less iteration),
* requiring JDK >= 1.5 or the backport-concurrent library on the classpath.
* Prefers a JDK 1.5+ CopyOnWriteArraySet to its backport-concurrent equivalent.
* Throws an IllegalStateException if no copy-on-write Set is available.
* @return the new Set instance
* @throws IllegalStateException if no copy-on-write Set is available
* @see java.util.concurrent.ConcurrentHashMap
* @see edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap
*/
public static Set createCopyOnWriteSet() {
if (JdkVersion.isAtLeastJava15()) {
logger.trace("Creating [java.util.concurrent.CopyOnWriteArraySet]");
return JdkConcurrentCollectionFactory.createCopyOnWriteArraySet();
}
else if (backportConcurrentAvailable) {
logger.trace("Creating [edu.emory.mathcs.backport.java.util.concurrent.CopyOnWriteArraySet]");
return BackportConcurrentCollectionFactory.createCopyOnWriteArraySet();
}
else {
throw new IllegalStateException("Cannot create CopyOnWriteArraySet - " +
"neither JDK 1.5 nor backport-concurrent available on the classpath");
}
}
/**
* Create a linked Map if possible: This implementation always
* creates a {@link java.util.LinkedHashMap}, since Spring 2.5
* requires JDK 1.4 anyway.
* @param initialCapacity the initial capacity of the Map
* @return the new Map instance
* @deprecated as of Spring 2.5, for usage on JDK 1.4 or higher
*/
public static Map createLinkedMapIfPossible(int initialCapacity) {
return new LinkedHashMap(initialCapacity);
}
/**
* Create a linked case-insensitive Map if possible: if Commons Collections
* 3.x is available, a CaseInsensitiveMap with ListOrderedMap decorator will
* be created. Else, a JDK {@link java.util.LinkedHashMap} will be used.
* @param initialCapacity the initial capacity of the Map
* @return the new Map instance
* @see org.apache.commons.collections.map.CaseInsensitiveMap
* @see org.apache.commons.collections.map.ListOrderedMap
*/
public static Map createLinkedCaseInsensitiveMapIfPossible(int initialCapacity) {
if (commonsCollections3Available) {
logger.trace("Creating [org.apache.commons.collections.map.ListOrderedMap/CaseInsensitiveMap]");
return CommonsCollectionFactory.createListOrderedCaseInsensitiveMap(initialCapacity);
}
else {
logger.debug("Falling back to [java.util.LinkedHashMap] for linked case-insensitive map");
return new LinkedHashMap(initialCapacity);
}
}
/**
* Create an identity Map if possible: This implementation always
* creates a {@link java.util.IdentityHashMap}, since Spring 2.5
* requires JDK 1.4 anyway.
* @param initialCapacity the initial capacity of the Map
* @return the new Map instance
* @deprecated as of Spring 2.5, for usage on JDK 1.4 or higher
*/
public static Map createIdentityMapIfPossible(int initialCapacity) {
return new IdentityHashMap(initialCapacity);
}
/**
* Create a concurrent Map if possible: that is, if running on JDK >= 1.5
* or if the backport-concurrent library is available. Prefers a JDK 1.5+
* ConcurrentHashMap to its backport-concurrent equivalent. Falls back
* to a plain synchronized HashMap if no concurrent Map is available.
* @param initialCapacity the initial capacity of the Map
* @return the new Map instance
* @see java.util.concurrent.ConcurrentHashMap
* @see edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap
*/
public static Map createConcurrentMapIfPossible(int initialCapacity) {
if (JdkVersion.isAtLeastJava15()) {
logger.trace("Creating [java.util.concurrent.ConcurrentHashMap]");
return JdkConcurrentCollectionFactory.createConcurrentHashMap(initialCapacity);
}
else if (backportConcurrentAvailable) {
logger.trace("Creating [edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap]");
return BackportConcurrentCollectionFactory.createConcurrentHashMap(initialCapacity);
}
else {
logger.debug("Falling back to plain synchronized [java.util.HashMap] for concurrent map");
return Collections.synchronizedMap(new HashMap(initialCapacity));
}
}
/**
* Create a concurrent Map with a dedicated {@link ConcurrentMap} interface,
* requiring JDK >= 1.5 or the backport-concurrent library on the classpath.
* Prefers a JDK 1.5+ ConcurrentHashMap to its backport-concurrent equivalent.
* Throws an IllegalStateException if no concurrent Map is available.
* @param initialCapacity the initial capacity of the Map
* @return the new ConcurrentMap instance
* @throws IllegalStateException if no concurrent Map is available
* @see java.util.concurrent.ConcurrentHashMap
* @see edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap
*/
public static ConcurrentMap createConcurrentMap(int initialCapacity) {
if (JdkVersion.isAtLeastJava15()) {
logger.trace("Creating [java.util.concurrent.ConcurrentHashMap]");
return new JdkConcurrentHashMap(initialCapacity);
}
else if (backportConcurrentAvailable) {
logger.trace("Creating [edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap]");
return new BackportConcurrentHashMap(initialCapacity);
}
else {
throw new IllegalStateException("Cannot create ConcurrentHashMap - " +
"neither JDK 1.5 nor backport-concurrent available on the classpath");
}
}
/**
* 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 true if the type is approximable,
* 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.
*
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
*/
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);
}
}
/**
* 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 true if the type is approximable,
* 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.
*
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 collection instance
* @see java.util.TreeMap
* @see java.util.LinkedHashMap
*/
public static Map createApproximateMap(Object map, int initialCapacity) {
if (map instanceof SortedMap) {
return new TreeMap(((SortedMap) map).comparator());
}
else {
return new LinkedHashMap(initialCapacity);
}
}
/**
* Actual creation of Commons Collections.
* In separate inner class to avoid runtime dependency on Commons Collections 3.x.
*/
private static abstract class CommonsCollectionFactory {
private static Map createListOrderedCaseInsensitiveMap(int initialCapacity) {
// Commons Collections does not support initial capacity of 0.
return ListOrderedMap.decorate(new CaseInsensitiveMap(initialCapacity == 0 ? 1 : initialCapacity));
}
}
/**
* Actual creation of JDK 1.5+ concurrent Collections.
* In separate inner class to avoid runtime dependency on JDK 1.5.
*/
private static abstract class JdkConcurrentCollectionFactory {
private static Set createCopyOnWriteArraySet() {
return new CopyOnWriteArraySet();
}
private static Map createConcurrentHashMap(int initialCapacity) {
return new ConcurrentHashMap(initialCapacity);
}
}
/**
* Actual creation of backport-concurrent Collections.
* In separate inner class to avoid runtime dependency on the backport-concurrent library.
*/
private static abstract class BackportConcurrentCollectionFactory {
private static Set createCopyOnWriteArraySet() {
return new edu.emory.mathcs.backport.java.util.concurrent.CopyOnWriteArraySet();
}
private static Map createConcurrentHashMap(int initialCapacity) {
return new edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap(initialCapacity);
}
}
/**
* ConcurrentMap adapter for the JDK ConcurrentHashMap class.
*/
private static class JdkConcurrentHashMap extends ConcurrentHashMap implements ConcurrentMap {
public JdkConcurrentHashMap(int initialCapacity) {
super(initialCapacity);
}
}
/**
* ConcurrentMap adapter for the backport-concurrent ConcurrentHashMap class.
*/
private static class BackportConcurrentHashMap
extends edu.emory.mathcs.backport.java.util.concurrent.ConcurrentHashMap
implements ConcurrentMap {
public BackportConcurrentHashMap(int initialCapacity) {
super(initialCapacity);
}
}
}