如何使用XML实体映射（orm.XML）持久化java.util.Properties

我有这样一个实体：

public class MyEntity implements Serializable {
  private static final long serialVersionUID = 1L;

  // some fields such as Long, String etc.

  private java.util.Properties properties;

  // getters, setters, equals, hashCode, toString ...
}

和XML实体映射

<?xml version="1.0" encoding="UTF-8"?>
<entity-mappings version="2.0"
  xmlns="http://java.sun.com/xml/ns/persistence/orm"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm http://java.sun.com/xml/ns/persistence/orm_2_0.xsd">

  <persistence-unit-metadata>
    <persistence-unit-defaults>
      <access>FIELD</access>
    </persistence-unit-defaults>
  </persistence-unit-metadata>

  <entity class="com.package.of.my.MyEntity">
    <table name="my_entity">
      <unique-constraint name="uniquefield">
        <column-name>uniquefield</column-name>
      </unique-constraint>
    </table>

    <!-- some named queries -->

    <attributes>
      <id name="id"><generated-value/></id>

      <!-- some <basic name="..."> columns -->

      <!-- What to put here for mapping the properties field? -->

      <!-- other mappings (one-to-one, one-to-many, many-to-many) -->
    </attributes>
  </entity>

  <!-- other entity mappings -->
</entity-mappings>

领域
唯一字段

如何理想地映射

java.util.Properties

对象

使用

会导致错误：无法解析属性。但是，它会向数据库表中添加BLOB列

Properties

使用

String

键和值，但实际上扩展了

Hashtable

（它实现了

Map

）。这看起来像是一对多。但是

对象

不是一个实体，因此也不起作用