org.springframework.util.LinkedMultiValueMap Maven / Gradle / Ivy
/*
* Copyright 2002-2020 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
*
* https://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.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
/**
* Simple implementation of {@link MultiValueMap} that wraps a {@link LinkedHashMap},
* storing multiple values in an {@link ArrayList}.
*
* This Map implementation is generally not thread-safe. It is primarily designed
* for data structures exposed from request objects, for use in a single thread only.
*
* @author Arjen Poutsma
* @author Juergen Hoeller
* @since 3.0
* @param the key type
* @param the value element type
*/
public class LinkedMultiValueMap extends MultiValueMapAdapter // new public base class in 5.3
implements Serializable, Cloneable {
private static final long serialVersionUID = 3801124242820219131L;
/**
* Create a new LinkedMultiValueMap that wraps a {@link LinkedHashMap}.
*/
public LinkedMultiValueMap() {
super(new LinkedHashMap<>());
}
/**
* Create a new LinkedMultiValueMap that wraps a {@link LinkedHashMap}
* with an initial capacity that can accommodate the specified number of
* elements without any immediate resize/rehash operations to be expected.
* @param expectedSize the expected number of elements (with a corresponding
* capacity to be derived so that no resize/rehash operations are needed)
* @see CollectionUtils#newLinkedHashMap(int)
*/
public LinkedMultiValueMap(int expectedSize) {
super(CollectionUtils.newLinkedHashMap(expectedSize));
}
/**
* Copy constructor: Create a new LinkedMultiValueMap with the same mappings as
* the specified Map. Note that this will be a shallow copy; its value-holding
* List entries will get reused and therefore cannot get modified independently.
* @param otherMap the Map whose mappings are to be placed in this Map
* @see #clone()
* @see #deepCopy()
*/
public LinkedMultiValueMap(Map> otherMap) {
super(new LinkedHashMap<>(otherMap));
}
/**
* Create a deep copy of this Map.
* @return a copy of this Map, including a copy of each value-holding List entry
* (consistently using an independent modifiable {@link ArrayList} for each entry)
* along the lines of {@code MultiValueMap.addAll} semantics
* @since 4.2
* @see #addAll(MultiValueMap)
* @see #clone()
*/
public LinkedMultiValueMap deepCopy() {
LinkedMultiValueMap copy = new LinkedMultiValueMap<>(size());
forEach((key, values) -> copy.put(key, new ArrayList<>(values)));
return copy;
}
/**
* Create a regular copy of this Map.
* @return a shallow copy of this Map, reusing this Map's value-holding List entries
* (even if some entries are shared or unmodifiable) along the lines of standard
* {@code Map.put} semantics
* @since 4.2
* @see #put(Object, List)
* @see #putAll(Map)
* @see LinkedMultiValueMap#LinkedMultiValueMap(Map)
* @see #deepCopy()
*/
@Override
public LinkedMultiValueMap clone() {
return new LinkedMultiValueMap<>(this);
}
}