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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.shiro.util;
20  
21  import java.io.Serializable;
22  import java.util.*;
23  
24  /**
25   * A {@code MapContext} provides a common base for context-based data storage in a {@link Map}.  Type-safe attribute
26   * retrieval is provided for subclasses with the {@link #getTypedValue(String, Class)} method.
27   *
28   * @see org.apache.shiro.subject.SubjectContext SubjectContext
29   * @see org.apache.shiro.session.mgt.SessionContext SessionContext
30   * @since 1.0
31   */
32  public class MapContext implements Map<String, Object>, Serializable {
33  
34      private static final long serialVersionUID = 5373399119017820322L;
35  
36      private final Map<String, Object> backingMap;
37  
38      public MapContext() {
39          this.backingMap = new HashMap<String, Object>();
40      }
41  
42      public MapContext(Map<String, Object> map) {
43          this();
44          if (!CollectionUtils.isEmpty(map)) {
45              this.backingMap.putAll(map);
46          }
47      }
48  
49      /**
50       * Performs a {@link #get get} operation but additionally ensures that the value returned is of the specified
51       * {@code type}.  If there is no value, {@code null} is returned.
52       *
53       * @param key  the attribute key to look up a value
54       * @param type the expected type of the value
55       * @param <E>  the expected type of the value
56       * @return the typed value or {@code null} if the attribute does not exist.
57       */
58      @SuppressWarnings({"unchecked"})
59      protected <E> E getTypedValue(String key, Class<E> type) {
60          E found = null;
61          Object o = backingMap.get(key);
62          if (o != null) {
63              if (!type.isAssignableFrom(o.getClass())) {
64                  String msg = "Invalid object found in SubjectContext Map under key [" + key + "].  Expected type " +
65                          "was [" + type.getName() + "], but the object under that key is of type " +
66                          "[" + o.getClass().getName() + "].";
67                  throw new IllegalArgumentException(msg);
68              }
69              found = (E) o;
70          }
71          return found;
72      }
73  
74      /**
75       * Places a value in this context map under the given key only if the given {@code value} argument is not null.
76       *
77       * @param key   the attribute key under which the non-null value will be stored
78       * @param value the non-null value to store.  If {@code null}, this method does nothing and returns immediately.
79       */
80      protected void nullSafePut(String key, Object value) {
81          if (value != null) {
82              put(key, value);
83          }
84      }
85  
86      public int size() {
87          return backingMap.size();
88      }
89  
90      public boolean isEmpty() {
91          return backingMap.isEmpty();
92      }
93  
94      public boolean containsKey(Object o) {
95          return backingMap.containsKey(o);
96      }
97  
98      public boolean containsValue(Object o) {
99          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 }