Mapper


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15  * Lesser General Public License for more details.
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21  */
22  package org.jboss.ejb.plugins.cmp.jdbc;
23  
24  
25  /**
26   * Generally, implementations of this interface map instances of one Java type
27   * into instances of another Java type.
28   * Mappers are used in cases when instances of "enum" types are used as CMP
29   * field values. In this case, a mapper represents a mediator and translates
30   * instances of "enum" to some id when that can be stored in a column when storing
31   * data and back from id to "enum" instance when data is loaded.
32   *
33   * @author <a HREF="mailto:alex@jboss.org">Alex Loubyansky</a>
34   */
35  public interface Mapper
36  {
37     /**
38      * This method is called when CMP field is stored.
39      * @param fieldValue - CMP field value
40      * @return column value.
41      */
42     Object   toColumnValue(Object   fieldValue);
43  
44     /**
45      * This method is called when CMP field is loaded.
46      * @param columnValue - loaded column value.
47      * @return CMP field value.
48      */
49     Object   toFieldValue(Object   columnValue);
50  }
51
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