AttributeAccessor


1   /*
2    * Copyright 2002-2006 the original author or authors.
3    *
4    * Licensed under the Apache License, Version 2.0 (the "License");
5    * you may not use this file except in compliance with the License.
6    * You may obtain a copy of the License at
7    *
8    *      http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS,
12   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13   * See the License for the specific language governing permissions and
14   * limitations under the License.
15   */
16  
17  package org.springframework.core;
18  
19  /**
20   * Interface defining a generic contract for attaching and accessing metadata
21   * to/from arbitrary objects.
22   *
23   * @author Rob Harrop
24   * @since 2.0
25   */
26  public interface AttributeAccessor {
27  
28      /**
29       * Set the attribute defined by <code>name</code> to the supplied   <code>value</code>.
30       * If <code>value</code> is <code>null</code>, the attribute is {@link #removeAttribute removed}.
31       * <p>In general, users should take care to prevent overlaps with other
32       * metadata attributes by using fully-qualified names, perhaps using
33       * class or package names as prefix.
34       * @param name the unique attribute key
35       * @param value the attribute value to be attached
36       */
37      void setAttribute(String   name, Object   value);
38  
39      /**
40       * Get the value of the attribute identified by <code>name</code>.
41       * Return <code>null</code> if the attribute doesn't exist.
42       * @param name the unique attribute key
43       * @return the current value of the attribute, if any
44       */
45      Object   getAttribute(String   name);
46  
47      /**
48       * Remove the attribute identified by <code>name</code> and return its value.
49       * Return <code>null</code> if no attribute under <code>name</code> is found.
50       * @param name the unique attribute key
51       * @return the last value of the attribute, if any
52       */
53      Object   removeAttribute(String   name);
54  
55      /**
56       * Return <code>true</code> if the attribute identified by <code>name</code> exists.
57       * Otherwise return <code>false</code>.
58       * @param name the unique attribute key
59       */
60      boolean hasAttribute(String   name);
61  
62      /**
63       * Return the names of all attributes.
64       */
65      String  [] attributeNames();
66  
67  }
68
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