001/*
002 * Copyright 2002-2018 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.core;
018
019import java.io.Serializable;
020import java.util.LinkedHashMap;
021import java.util.Map;
022
023import org.springframework.lang.Nullable;
024import org.springframework.util.Assert;
025import org.springframework.util.StringUtils;
026
027/**
028 * Support class for {@link AttributeAccessor AttributeAccessors}, providing
029 * a base implementation of all methods. To be extended by subclasses.
030 *
031 * <p>{@link Serializable} if subclasses and all attribute values are {@link Serializable}.
032 *
033 * @author Rob Harrop
034 * @author Juergen Hoeller
035 * @since 2.0
036 */
037@SuppressWarnings("serial")
038public abstract class AttributeAccessorSupport implements AttributeAccessor, Serializable {
039
040        /** Map with String keys and Object values. */
041        private final Map<String, Object> attributes = new LinkedHashMap<>();
042
043
044        @Override
045        public void setAttribute(String name, @Nullable Object value) {
046                Assert.notNull(name, "Name must not be null");
047                if (value != null) {
048                        this.attributes.put(name, value);
049                }
050                else {
051                        removeAttribute(name);
052                }
053        }
054
055        @Override
056        @Nullable
057        public Object getAttribute(String name) {
058                Assert.notNull(name, "Name must not be null");
059                return this.attributes.get(name);
060        }
061
062        @Override
063        @Nullable
064        public Object removeAttribute(String name) {
065                Assert.notNull(name, "Name must not be null");
066                return this.attributes.remove(name);
067        }
068
069        @Override
070        public boolean hasAttribute(String name) {
071                Assert.notNull(name, "Name must not be null");
072                return this.attributes.containsKey(name);
073        }
074
075        @Override
076        public String[] attributeNames() {
077                return StringUtils.toStringArray(this.attributes.keySet());
078        }
079
080
081        /**
082         * Copy the attributes from the supplied AttributeAccessor to this accessor.
083         * @param source the AttributeAccessor to copy from
084         */
085        protected void copyAttributesFrom(AttributeAccessor source) {
086                Assert.notNull(source, "Source must not be null");
087                String[] attributeNames = source.attributeNames();
088                for (String attributeName : attributeNames) {
089                        setAttribute(attributeName, source.getAttribute(attributeName));
090                }
091        }
092
093
094        @Override
095        public boolean equals(@Nullable Object other) {
096                return (this == other || (other instanceof AttributeAccessorSupport &&
097                                this.attributes.equals(((AttributeAccessorSupport) other).attributes)));
098        }
099
100        @Override
101        public int hashCode() {
102                return this.attributes.hashCode();
103        }
104
105}