Java 使用XMLAdapter将XML对象列表解组到HashMap中

我得到了以下XML

<demographics>
  <field>
    <value>03290</value>
    <XMLtag>study_identifier</XMLtag>
  </field>
  <field>
    <value>somename</value>
    <XMLtag>name</XMLtag>
  </field>
  <filename>bbRad_BUILD_dem_03290_BUILD_006742.xml</filename>
  <study_cache_dir>somestring</study_cache_dir>
</demographics>

如果我解组XML，它工作正常，

multivalueFields

包含两个

Field2

对象的列表。我想要的是将

列表

转换为

HashMap

，其中字符串键将是

字段2

对象的

xmlTag

值

到目前为止，我已经厌倦了按如下方式更改Demographics2类和使用XmlAdapter：

@XmlElement( name = "field" )
@XmlJavaTypeAdapter( MultiValueFieldsAdapter.class )
private Map< String, Field2> mutivalueFields;

---

@user23123412如果没有，我仍然无法让XmlAdapter正常工作：（您可以添加一个初始化为null的临时字段

Map

，并在第一次调用getMutiValueFieldsMap（）时创建和保存映射。

public class Field2
{
    @XmlElement( name = "XMLtag")
    private String xmlTag;
    @XmlElement( name = "value" )
    private String value;
}

@XmlElement( name = "field" )
@XmlJavaTypeAdapter( MultiValueFieldsAdapter.class )
private Map< String, Field2> mutivalueFields;

public class MultiValueFieldsAdapter extends XmlAdapter< List<Field2>, Map<String, Field2>> {

   @Override
   public List<Field2> marshal( Map<String, Field2> arg0) throws Exception {

       // loop all in Map and just add the Field2 objects to a list then
       // return the list
       return null;
   }

    @Override
    public Map<String, Field2> unmarshal( List<Field2> arg0 ) throws Exception {

         // The problem is here arg0 will be emtpy list, unless we make arg0 a Field2 object
         // it seems to be calling unmarshal for each Field2 object, rather than some list

         // loop each Field2 and add to Map
         Map<String, Field2> newMap = new HashMap<String, Field2>( arg.length() );

         for ( Field2 f : arg0 )
             newMap.put( f.xmlTag, f );
    }
}

Field2 nameField = multivalueFields.get( "name" );