xstream是個好東西。對于配置文件的讀取很方便。在mybog中我就用到了。不過今天打算用yupoo的api來做相冊。發現xstream對于xmlnode的attribute解析支持不是那么的好。
對于這種節點格式的非常的簡單

簡單的alias一下就可以讀到值了
可是Yupoo的api返回的xmlrpc的結果是這樣的
這樣就load不到值了。沒法去mailist里面找答案，果然有人問。

Hello,

I am not sure about the subject but here is what I needed help for:

XML:

<field name="value">I am a Field.</field>

I have already tried several structures and nothing seem to work.

Is this possible for XStream? :)

How is the Java class form to support this?

Thanks!




有人回答是看Converter的文檔。果然找到答案了。
自己寫一個converter就可以了。
下面是我的converter
package?com.jdkcn.xstream;

import?java.util.ArrayList;
import?java.util.List;

import?com.jdkcn.yupoo.YupooPhoto;
import?com.jdkcn.yupoo.YupooResult;
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;

/**
?*?@author?<a?href="mailto:rory.cn@gmail.com">somebody</a>
?*?@since?Jan?16,?2007?6:12:35?PM
?*?@version?$Id?YupooResultConverter.java$
?*/
public?class?YupooResultConverter?implements?Converter?{
????/*?(non-Javadoc)
?????*?@see?com.thoughtworks.xstream.converters.Converter#marshal(java.lang.Object,?com.thoughtworks.xstream.io.HierarchicalStreamWriter,?com.thoughtworks.xstream.converters.MarshallingContext)
?????*/
????public?void?marshal(Object?obj,?HierarchicalStreamWriter?writer,?MarshallingContext?context)?{
????????//?FIXME?unfinish.
????}

????/*?(non-Javadoc)
?????*?@see?com.thoughtworks.xstream.converters.Converter#unmarshal(com.thoughtworks.xstream.io.HierarchicalStreamReader,?com.thoughtworks.xstream.converters.UnmarshallingContext)
?????*/
????public?Object?unmarshal(HierarchicalStreamReader?reader,?UnmarshallingContext?context)?{
????????YupooResult?result?=?new?YupooResult();
????????result.setPage(new?Integer(reader.getAttribute("page")));
????????result.setPages(new?Integer(reader.getAttribute("pages")));
????????result.setPerpage(new?Integer(reader.getAttribute("perpage")));
????????result.setTotal(new?Integer(reader.getAttribute("total")));
????????reader.moveDown();
????????List<YupooPhoto>?photos?=?new?ArrayList<YupooPhoto>();
????????while(reader.hasMoreChildren())?{
????????????reader.moveDown();
????????????YupooPhoto?photo?=?new?YupooPhoto();
????????????photo.setDir(reader.getAttribute("dir"));
????????????photo.setFilename(reader.getAttribute("filename"));
????????????photo.setHost(reader.getAttribute("host"));
????????????photo.setId(reader.getAttribute("id"));
????????????photo.setOwner(reader.getAttribute("owner"));
????????????photo.setTitle(reader.getAttribute("title"));
????????????photos.add(photo);
????????????reader.moveUp();
????????}
????????result.setPhotos(photos);
????????return?result;
????}
????/*?(non-Javadoc)
?????*?@see?com.thoughtworks.xstream.converters.ConverterMatcher#canConvert(java.lang.Class)
?????*/
????public?boolean?canConvert(Class?clazz)?{
????????return?clazz.equals(YupooResult.class);
????}
}

然后調用的地方修改一下就ok了。
XStream?stream?=?new?XStream();
stream.registerConverter(new?YupooResultConverter());
stream.alias("result",?YupooResult.class);



參考:
http://xstream.codehaus.org/converter-tutorial.html

2007年1月18日更新。
這里感謝網友 Ivan Chen（西濱）?的提示。原來新版的xstream可以簡單的解決了。在1.2.1的doc里面找到了這個兩個方法。

useAttributeFor

public void useAttributeFor(java.lang.String?fieldName,
                            java.lang.Class?type)

Use an XML attribute for a field or a specific type.

Parameters:

fieldName - the name of the field

type - the Class of the type to be rendered as XML attribute

Throws:

XStream.InitializationException - if no AttributeMapper is available

Since:

1.2

---

useAttributeFor

public void useAttributeFor(java.lang.Class?type)

Use an XML attribute for an arbotrary type.

Parameters:

type - the Class of the type to be rendered as XML attribute

Throws:

XStream.InitializationException - if no AttributeMapper is available

Since:

1.2

這兩個方法都是從1.2開始支持的。
也不用自己寫converter了。這樣就可以了

?? 除經特別注明外,本文章版權歸莫多泡泡所有.
署名,非商業用途,保持一致.???somebody(莫多)