org.springframework.util.LinkedCaseInsensitiveMap Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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.util;
import java.io.Serializable;
import java.util.Collection;
import java.util.HashMap;
import java.util.LinkedHashMap;
import java.util.Locale;
import java.util.Map;
import java.util.Set;
import java.util.function.Function;
import org.springframework.lang.Nullable;
/**
* {@link LinkedHashMap} variant that stores String keys in a case-insensitive
* manner, for example for key-based access in a results table.
*
* Preserves the original order as well as the original casing of keys,
* while allowing for contains, get and remove calls with any case of key.
*
*
Does not support {@code null} keys.
*
* @author Juergen Hoeller
* @since 3.0
* @param the value type
*/
@SuppressWarnings("serial")
public class LinkedCaseInsensitiveMap implements Map, Serializable, Cloneable {
private final LinkedHashMap targetMap;
private final HashMap caseInsensitiveKeys;
private final Locale locale;
/**
* Create a new LinkedCaseInsensitiveMap that stores case-insensitive keys
* according to the default Locale (by default in lower case).
* @see #convertKey(String)
*/
public LinkedCaseInsensitiveMap() {
this((Locale) null);
}
/**
* Create a new LinkedCaseInsensitiveMap that stores case-insensitive keys
* according to the given Locale (by default in lower case).
* @param locale the Locale to use for case-insensitive key conversion
* @see #convertKey(String)
*/
public LinkedCaseInsensitiveMap(@Nullable Locale locale) {
this(16, locale);
}
/**
* Create a new LinkedCaseInsensitiveMap that wraps a {@link LinkedHashMap}
* with the given initial capacity and stores case-insensitive keys
* according to the default Locale (by default in lower case).
* @param initialCapacity the initial capacity
* @see #convertKey(String)
*/
public LinkedCaseInsensitiveMap(int initialCapacity) {
this(initialCapacity, null);
}
/**
* Create a new LinkedCaseInsensitiveMap that wraps a {@link LinkedHashMap}
* with the given initial capacity and stores case-insensitive keys
* according to the given Locale (by default in lower case).
* @param initialCapacity the initial capacity
* @param locale the Locale to use for case-insensitive key conversion
* @see #convertKey(String)
*/
public LinkedCaseInsensitiveMap(int initialCapacity, @Nullable Locale locale) {
this.targetMap = new LinkedHashMap(initialCapacity) {
@Override
public boolean containsKey(Object key) {
return LinkedCaseInsensitiveMap.this.containsKey(key);
}
@Override
protected boolean removeEldestEntry(Map.Entry eldest) {
boolean doRemove = LinkedCaseInsensitiveMap.this.removeEldestEntry(eldest);
if (doRemove) {
caseInsensitiveKeys.remove(convertKey(eldest.getKey()));
}
return doRemove;
}
};
this.caseInsensitiveKeys = new HashMap<>(initialCapacity);
this.locale = (locale != null ? locale : Locale.getDefault());
}
/**
* Copy constructor.
*/
@SuppressWarnings("unchecked")
private LinkedCaseInsensitiveMap(LinkedCaseInsensitiveMap other) {
this.targetMap = (LinkedHashMap) other.targetMap.clone();
this.caseInsensitiveKeys = (HashMap) other.caseInsensitiveKeys.clone();
this.locale = other.locale;
}
// Implementation of java.util.Map
@Override
public int size() {
return this.targetMap.size();
}
@Override
public boolean isEmpty() {
return this.targetMap.isEmpty();
}
@Override
public boolean containsKey(Object key) {
return (key instanceof String && this.caseInsensitiveKeys.containsKey(convertKey((String) key)));
}
@Override
public boolean containsValue(Object value) {
return this.targetMap.containsValue(value);
}
@Override
@Nullable
public V get(Object key) {
if (key instanceof String) {
String caseInsensitiveKey = this.caseInsensitiveKeys.get(convertKey((String) key));
if (caseInsensitiveKey != null) {
return this.targetMap.get(caseInsensitiveKey);
}
}
return null;
}
@Override
@Nullable
public V getOrDefault(Object key, V defaultValue) {
if (key instanceof String) {
String caseInsensitiveKey = this.caseInsensitiveKeys.get(convertKey((String) key));
if (caseInsensitiveKey != null) {
return this.targetMap.get(caseInsensitiveKey);
}
}
return defaultValue;
}
@Override
@Nullable
public V put(String key, @Nullable V value) {
String oldKey = this.caseInsensitiveKeys.put(convertKey(key), key);
V oldKeyValue = null;
if (oldKey != null && !oldKey.equals(key)) {
oldKeyValue = this.targetMap.remove(oldKey);
}
V oldValue = this.targetMap.put(key, value);
return (oldKeyValue != null ? oldKeyValue : oldValue);
}
@Override
public void putAll(Map map) {
if (map.isEmpty()) {
return;
}
map.forEach(this::put);
}
@Override
@Nullable
public V putIfAbsent(String key, @Nullable V value) {
String oldKey = this.caseInsensitiveKeys.putIfAbsent(convertKey(key), key);
if (oldKey != null) {
return this.targetMap.get(oldKey);
}
return this.targetMap.putIfAbsent(key, value);
}
@Override
@Nullable
public V computeIfAbsent(String key, Function mappingFunction) {
String oldKey = this.caseInsensitiveKeys.putIfAbsent(convertKey(key), key);
if (oldKey != null) {
return this.targetMap.get(oldKey);
}
return this.targetMap.computeIfAbsent(key, mappingFunction);
}
@Override
@Nullable
public V remove(Object key) {
if (key instanceof String) {
String caseInsensitiveKey = this.caseInsensitiveKeys.remove(convertKey((String) key));
if (caseInsensitiveKey != null) {
return this.targetMap.remove(caseInsensitiveKey);
}
}
return null;
}
@Override
public void clear() {
this.caseInsensitiveKeys.clear();
this.targetMap.clear();
}
@Override
public Set keySet() {
return this.targetMap.keySet();
}
@Override
public Collection values() {
return this.targetMap.values();
}
@Override
public Set> entrySet() {
return this.targetMap.entrySet();
}
@Override
public LinkedCaseInsensitiveMap clone() {
return new LinkedCaseInsensitiveMap<>(this);
}
@Override
public boolean equals(Object obj) {
return this.targetMap.equals(obj);
}
@Override
public int hashCode() {
return this.targetMap.hashCode();
}
@Override
public String toString() {
return this.targetMap.toString();
}
// Specific to LinkedCaseInsensitiveMap
/**
* Return the locale used by this {@code LinkedCaseInsensitiveMap}.
* Used for case-insensitive key conversion.
* @since 4.3.10
* @see #LinkedCaseInsensitiveMap(Locale)
* @see #convertKey(String)
*/
public Locale getLocale() {
return this.locale;
}
/**
* Convert the given key to a case-insensitive key.
* The default implementation converts the key
* to lower-case according to this Map's Locale.
* @param key the user-specified key
* @return the key to use for storing
* @see String#toLowerCase(Locale)
*/
protected String convertKey(String key) {
return key.toLowerCase(getLocale());
}
/**
* Determine whether this map should remove the given eldest entry.
* @param eldest the candidate entry
* @return {@code true} for removing it, {@code false} for keeping it
* @see LinkedHashMap#removeEldestEntry
*/
protected boolean removeEldestEntry(Map.Entry eldest) {
return false;
}
}