/*
    *    Copyright 2009-2021 the original author or authors.
    *
    *    Licensed under the Apache License, Version 2.0 (the "License");
    *    you may not use this file except in compliance with the License.
    *    You may obtain a copy of the License at
    *
    *       http://www.apache.org/licenses/LICENSE-2.0
    *
   *    Unless required by applicable law or agreed to in writing, software
   *    distributed under the License is distributed on an "AS IS" BASIS,
   *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   *    See the License for the specific language governing permissions and
   *    limitations under the License.
   */
  package org.apache.ibatis.annotations;
  
  import java.lang.annotation.Documented;
  import java.lang.annotation.ElementType;
  import java.lang.annotation.Retention;
  import java.lang.annotation.RetentionPolicy;
  import java.lang.annotation.Target;
  
  /**
   * The annotation that specify the property name(or column name) for a key value of {@link java.util.Map}.
   *
   * <p>
   * <b>How to use:</b>
   *
   * <pre>
   * public interface UserMapper {
   *   &#064;MapKey("id")
   *   &#064;Select("SELECT id, name FROM users WHERE name LIKE #{name} || '%")
   *   Map&lt;Integer, User&gt; selectByStartingWithName(String name);
   * }
   * </pre>
   *
   * @author Clinton Begin
   */
  @Documented
  @Retention(RetentionPolicy.RUNTIME)
  @Target(ElementType.METHOD)
  public @interface MapKey {
    /**
     * Returns the property name(or column name) for a key value of {@link java.util.Map}.
     *
     * @return the property name(or column name)
     */
    String value();
  }