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1   /*
2    *    Copyright 2009-2023 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    *       https://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  package org.apache.ibatis.annotations;
17  
18  import java.lang.annotation.Documented;
19  import java.lang.annotation.ElementType;
20  import java.lang.annotation.Retention;
21  import java.lang.annotation.RetentionPolicy;
22  import java.lang.annotation.Target;
23  
24  /**
25   * The annotation that specify the property name(or column name) for a key value of {@link java.util.Map}.
26   * <p>
27   * <b>How to use:</b>
28   *
29   * <pre>
30   * public interface UserMapper {
31   *   &#064;MapKey("id")
32   *   &#064;Select("SELECT id, name FROM users WHERE name LIKE #{name} || '%")
33   *   Map&lt;Integer, User&gt; selectByStartingWithName(String name);
34   * }
35   * </pre>
36   *
37   * @author Clinton Begin
38   */
39  @Documented
40  @Retention(RetentionPolicy.RUNTIME)
41  @Target(ElementType.METHOD)
42  public @interface MapKey {
43    /**
44     * Returns the property name(or column name) for a key value of {@link java.util.Map}.
45     *
46     * @return the property name(or column name)
47     */
48    String value();
49  }