001/*
002 * Copyright 2002-2019 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.ui;
018
019import java.util.Collection;
020import java.util.Map;
021import java.util.concurrent.ConcurrentHashMap;
022
023import org.springframework.core.Conventions;
024import org.springframework.lang.Nullable;
025import org.springframework.util.Assert;
026
027/**
028 * Implementation of the {@link Model} interface based on a {@link ConcurrentHashMap}
029 * for use in concurrent scenarios.
030 *
031 * <p>Exposed to handler methods by Spring WebFlux, typically via a declaration of the
032 * {@link Model} interface. There is typically no need to create it within user code.
033 * If necessary a handler method can return a regular {@code java.util.Map},
034 * likely a {@code java.util.ConcurrentMap}, for a pre-determined model.
035 *
036 * @author Rossen Stoyanchev
037 * @since 5.0
038 */
039@SuppressWarnings("serial")
040public class ConcurrentModel extends ConcurrentHashMap<String, Object> implements Model {
041
042        /**
043         * Construct a new, empty {@code ConcurrentModel}.
044         */
045        public ConcurrentModel() {
046        }
047
048        /**
049         * Construct a new {@code ModelMap} containing the supplied attribute
050         * under the supplied name.
051         * @see #addAttribute(String, Object)
052         */
053        public ConcurrentModel(String attributeName, Object attributeValue) {
054                addAttribute(attributeName, attributeValue);
055        }
056
057        /**
058         * Construct a new {@code ModelMap} containing the supplied attribute.
059         * Uses attribute name generation to generate the key for the supplied model
060         * object.
061         * @see #addAttribute(Object)
062         */
063        public ConcurrentModel(Object attributeValue) {
064                addAttribute(attributeValue);
065        }
066
067
068        @Override
069        public Object put(String key, Object value) {
070                if (value != null) {
071                        return super.put(key, value);
072                }
073                else {
074                        return remove(key);
075                }
076        }
077
078        @Override
079        public void putAll(Map<? extends String, ?> map) {
080                for (Map.Entry<? extends String, ?> entry : map.entrySet()) {
081                        put(entry.getKey(), entry.getValue());
082                }
083        }
084
085        /**
086         * Add the supplied attribute under the supplied name.
087         * @param attributeName the name of the model attribute (never {@code null})
088         * @param attributeValue the model attribute value (ignored if {@code null},
089         * just removing an existing entry if any)
090         */
091        @Override
092        public ConcurrentModel addAttribute(String attributeName, @Nullable Object attributeValue) {
093                Assert.notNull(attributeName, "Model attribute name must not be null");
094                put(attributeName, attributeValue);
095                return this;
096        }
097
098        /**
099         * Add the supplied attribute to this {@code Map} using a
100         * {@link org.springframework.core.Conventions#getVariableName generated name}.
101         * <p><i>Note: Empty {@link Collection Collections} are not added to
102         * the model when using this method because we cannot correctly determine
103         * the true convention name. View code should check for {@code null} rather
104         * than for empty collections as is already done by JSTL tags.</i>
105         * @param attributeValue the model attribute value (never {@code null})
106         */
107        @Override
108        public ConcurrentModel addAttribute(Object attributeValue) {
109                Assert.notNull(attributeValue, "Model attribute value must not be null");
110                if (attributeValue instanceof Collection && ((Collection<?>) attributeValue).isEmpty()) {
111                        return this;
112                }
113                return addAttribute(Conventions.getVariableName(attributeValue), attributeValue);
114        }
115
116        /**
117         * Copy all attributes in the supplied {@code Collection} into this
118         * {@code Map}, using attribute name generation for each element.
119         * @see #addAttribute(Object)
120         */
121        @Override
122        public ConcurrentModel addAllAttributes(@Nullable Collection<?> attributeValues) {
123                if (attributeValues != null) {
124                        for (Object attributeValue : attributeValues) {
125                                addAttribute(attributeValue);
126                        }
127                }
128                return this;
129        }
130
131        /**
132         * Copy all attributes in the supplied {@code Map} into this {@code Map}.
133         * @see #addAttribute(String, Object)
134         */
135        @Override
136        public ConcurrentModel addAllAttributes(@Nullable Map<String, ?> attributes) {
137                if (attributes != null) {
138                        putAll(attributes);
139                }
140                return this;
141        }
142
143        /**
144         * Copy all attributes in the supplied {@code Map} into this {@code Map},
145         * with existing objects of the same name taking precedence (i.e. not getting
146         * replaced).
147         */
148        @Override
149        public ConcurrentModel mergeAttributes(@Nullable Map<String, ?> attributes) {
150                if (attributes != null) {
151                        attributes.forEach((key, value) -> {
152                                if (!containsKey(key)) {
153                                        put(key, value);
154                                }
155                        });
156                }
157                return this;
158        }
159
160        /**
161         * Does this model contain an attribute of the given name?
162         * @param attributeName the name of the model attribute (never {@code null})
163         * @return whether this model contains a corresponding attribute
164         */
165        @Override
166        public boolean containsAttribute(String attributeName) {
167                return containsKey(attributeName);
168        }
169
170        @Override
171        @Nullable
172        public Object getAttribute(String attributeName) {
173                return get(attributeName);
174        }
175
176        @Override
177        public Map<String, Object> asMap() {
178                return this;
179        }
180
181}