001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *     http://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.shiro.util;
020
021import java.io.Serializable;
022import java.util.*;
023
024/**
025 * A {@code MapContext} provides a common base for context-based data storage in a {@link Map}.  Type-safe attribute
026 * retrieval is provided for subclasses with the {@link #getTypedValue(String, Class)} method.
027 *
028 * @see org.apache.shiro.subject.SubjectContext SubjectContext
029 * @see org.apache.shiro.session.mgt.SessionContext SessionContext
030 * @since 1.0
031 */
032public class MapContext implements Map<String, Object>, Serializable {
033
034    private static final long serialVersionUID = 5373399119017820322L;
035
036    private final Map<String, Object> backingMap;
037
038    public MapContext() {
039        this.backingMap = new HashMap<String, Object>();
040    }
041
042    public MapContext(Map<String, Object> map) {
043        this();
044        if (!CollectionUtils.isEmpty(map)) {
045            this.backingMap.putAll(map);
046        }
047    }
048
049    /**
050     * Performs a {@link #get get} operation but additionally ensures that the value returned is of the specified
051     * {@code type}.  If there is no value, {@code null} is returned.
052     *
053     * @param key  the attribute key to look up a value
054     * @param type the expected type of the value
055     * @param <E>  the expected type of the value
056     * @return the typed value or {@code null} if the attribute does not exist.
057     */
058    @SuppressWarnings({"unchecked"})
059    protected <E> E getTypedValue(String key, Class<E> type) {
060        E found = null;
061        Object o = backingMap.get(key);
062        if (o != null) {
063            if (!type.isAssignableFrom(o.getClass())) {
064                String msg = "Invalid object found in SubjectContext Map under key [" + key + "].  Expected type " +
065                        "was [" + type.getName() + "], but the object under that key is of type " +
066                        "[" + o.getClass().getName() + "].";
067                throw new IllegalArgumentException(msg);
068            }
069            found = (E) o;
070        }
071        return found;
072    }
073
074    /**
075     * Places a value in this context map under the given key only if the given {@code value} argument is not null.
076     *
077     * @param key   the attribute key under which the non-null value will be stored
078     * @param value the non-null value to store.  If {@code null}, this method does nothing and returns immediately.
079     */
080    protected void nullSafePut(String key, Object value) {
081        if (value != null) {
082            put(key, value);
083        }
084    }
085
086    public int size() {
087        return backingMap.size();
088    }
089
090    public boolean isEmpty() {
091        return backingMap.isEmpty();
092    }
093
094    public boolean containsKey(Object o) {
095        return backingMap.containsKey(o);
096    }
097
098    public boolean containsValue(Object o) {
099        return backingMap.containsValue(o);
100    }
101
102    public Object get(Object o) {
103        return backingMap.get(o);
104    }
105
106    public Object put(String s, Object o) {
107        return backingMap.put(s, o);
108    }
109
110    public Object remove(Object o) {
111        return backingMap.remove(o);
112    }
113
114    public void putAll(Map<? extends String, ?> map) {
115        backingMap.putAll(map);
116    }
117
118    public void clear() {
119        backingMap.clear();
120    }
121
122    public Set<String> keySet() {
123        return Collections.unmodifiableSet(backingMap.keySet());
124    }
125
126    public Collection<Object> values() {
127        return Collections.unmodifiableCollection(backingMap.values());
128    }
129
130    public Set<Entry<String, Object>> entrySet() {
131        return Collections.unmodifiableSet(backingMap.entrySet());
132    }
133}