如何将 XML 转换为 java.util.Map，反之亦然？

Question

我正在搜索一个轻量级 API（最好是单一类）来转换一个

Map<String,String> map = new HashMap<String,String();

到 XML，反之亦然，将 XML 转换回 Map<String,String> 。

例子：

 Map<String,String> map = new HashMap<String,String();
map.put("name","chris");
map.put("island","faranga");

MagicAPI.toXML(map,"root");

结果：

 <root>
  <name>chris</chris>
  <island>faranga</island>
</root>

然后回来：

 Map<String,String> map = MagicAPI.fromXML("...");

我不想使用 JAXB 或 JSON 转换 API 。它不必处理嵌套映射或属性或其他任何事情，只是这种简单的情况。有什么建议么？

---

我创建了一个工作复制和粘贴示例。感谢 fvu 和 Michal Bernhard 。

下载最新的 XStream 框架，“仅核心”就足够了。

 Map<String,Object> map = new HashMap<String,Object>();
map.put("name","chris");
map.put("island","faranga");

// convert to XML
XStream xStream = new XStream(new DomDriver());
xStream.alias("map", java.util.Map.class);
String xml = xStream.toXML(map);

// from XML, convert back to map
Map<String,Object> map2 = (Map<String,Object>) xStream.fromXML(xml);

不需要转换器或任何其他东西。只需 xstream-xyzjar 就足够了。

原文由 Chris 发布，翻译遵循 CC BY-SA 4.0 许可协议

Answer 1

XStream！

更新：我按照评论中的要求添加了解组部分..

 import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.converters.Converter;
import com.thoughtworks.xstream.converters.MarshallingContext;
import com.thoughtworks.xstream.converters.UnmarshallingContext;
import com.thoughtworks.xstream.io.HierarchicalStreamReader;
import com.thoughtworks.xstream.io.HierarchicalStreamWriter;

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

public class Test {

    public static void main(String[] args) {

        Map<String,String> map = new HashMap<String,String>();
        map.put("name","chris");
        map.put("island","faranga");

        XStream magicApi = new XStream();
        magicApi.registerConverter(new MapEntryConverter());
        magicApi.alias("root", Map.class);

        String xml = magicApi.toXML(map);
        System.out.println("Result of tweaked XStream toXml()");
        System.out.println(xml);

        Map<String, String> extractedMap = (Map<String, String>) magicApi.fromXML(xml);
        assert extractedMap.get("name").equals("chris");
        assert extractedMap.get("island").equals("faranga");

    }

    public static class MapEntryConverter implements Converter {

        public boolean canConvert(Class clazz) {
            return AbstractMap.class.isAssignableFrom(clazz);
        }

        public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) {

            AbstractMap map = (AbstractMap) value;
            for (Object obj : map.entrySet()) {
                Map.Entry entry = (Map.Entry) obj;
                writer.startNode(entry.getKey().toString());
                Object val = entry.getValue();
                if ( null != val ) {
                    writer.setValue(val.toString());
                }
                writer.endNode();
            }

        }

        public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {

            Map<String, String> map = new HashMap<String, String>();

            while(reader.hasMoreChildren()) {
                reader.moveDown();

                String key = reader.getNodeName(); // nodeName aka element's name
                String value = reader.getValue();
                map.put(key, value);

                reader.moveUp();
            }

            return map;
        }

    }

}

原文由 Michal Bernhard 发布，翻译遵循 CC BY-SA 3.0 许可协议

Answer 2

这里的 XStream 转换器包括 unmarshall

 public class MapEntryConverter implements Converter{
public boolean canConvert(Class clazz) {
    return AbstractMap.class.isAssignableFrom(clazz);
}

public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext context) {
    AbstractMap<String,String> map = (AbstractMap<String,String>) value;
    for (Entry<String,String> entry : map.entrySet()) {
        writer.startNode(entry.getKey().toString());
        writer.setValue(entry.getValue().toString());
        writer.endNode();
    }
}

public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {
    Map<String, String> map = new HashMap<String, String>();

    while(reader.hasMoreChildren()) {
        reader.moveDown();
        map.put(reader.getNodeName(), reader.getValue());
        reader.moveUp();
    }
    return map;
}

原文由 Vikas Gujjar 发布，翻译遵循 CC BY-SA 3.0 许可协议