JAXB:如何将映射编组为 <key>value</key>

2022-01-19 00:00:00 xml java jaxb jaxb2

问题是关于 JAXB 地图编组 - 有很多关于如何将地图编组为如下结构的示例:

The question is about JAXB Map marshalling - there is plenty of examples on how to marhsall a Map into a structure like follows:

<map>
  <entry>
    <key> KEY </key>
    <value> VALUE </value>
  </entry>
  <entry>
    <key> KEY2 </key>
    <value> VALUE2 </value>
  </entry>
  <entry>
  ...
</map>

事实上，JAXB 本身就支持这一点.然而，我需要的是 XML，其中 key 是元素名称，value 是它的内容:

In fact, this is natively supported by JAXB. What I need, however, is the XML where key is the element name, and value is its content:

<map>
  <key> VALUE </key>
  <key2> VALUE2 </key2>
 ...
</map>

我没有按照 JAXB 开发人员推荐的方式成功实现我的地图适配器 (https://jaxb.dev.java.net/guide/Mapping_your_favorite_class.html)，根据我的需要，他-动态属性名称:)

I didn't succeed implementing my Map adapter the way it is recommended by JAXB developers (https://jaxb.dev.java.net/guide/Mapping_your_favorite_class.html), as I need, he - dynamic attribute name :)

有什么解决办法吗?

附:目前，我必须为要编组为 XML 的每组典型的键值对创建一个专用的容器类 - 它可以工作，但我必须创建太多的这些帮助容器.

P.S. Currently I have to create a dedicated container class for each typical set of key-value pairs I want to marshall to XML - it works, but I have to create way too many of these helper containers.

推荐答案

提供的代码对我不起作用.我找到了另一种地图方式:

the code provided didn't work for me. I found another way to Map :

地图元素:

package com.cellfish.mediadb.rest.lucene;

import javax.xml.bind.annotation.XmlElement;

class MapElements
{
  @XmlElement public String  key;
  @XmlElement public Integer value;

  private MapElements() {} //Required by JAXB

  public MapElements(String key, Integer value)
  {
    this.key   = key;
    this.value = value;
  }
}

地图适配器:

import java.util.HashMap;
import java.util.Map;

import javax.xml.bind.annotation.adapters.XmlAdapter;

class MapAdapter extends XmlAdapter<MapElements[], Map<String, Integer>> {
    public MapElements[] marshal(Map<String, Integer> arg0) throws Exception {
        MapElements[] mapElements = new MapElements[arg0.size()];
        int i = 0;
        for (Map.Entry<String, Integer> entry : arg0.entrySet())
            mapElements[i++] = new MapElements(entry.getKey(), entry.getValue());

        return mapElements;
    }

    public Map<String, Integer> unmarshal(MapElements[] arg0) throws Exception {
        Map<String, Integer> r = new HashMap<String, Integer>();
        for (MapElements mapelement : arg0)
            r.put(mapelement.key, mapelement.value);
        return r;
    }
}

根元素:

import java.util.HashMap;
import java.util.Map;

import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

@XmlRootElement
public class Root {

    private Map<String, Integer> mapProperty;

    public Root() {
        mapProperty = new HashMap<String, Integer>();
    }

    @XmlJavaTypeAdapter(MapAdapter.class)
    public Map<String, Integer> getMapProperty() {
        return mapProperty;
    }

    public void setMapProperty(Map<String, Integer> map) {
        this.mapProperty = map;
    }

}

我在这个网站上找到了代码:http://www.developpez.net/forums/d972324/java/general-java/xml/hashmap-jaxb/

I found the code in this website : http://www.developpez.net/forums/d972324/java/general-java/xml/hashmap-jaxb/

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