2006年12月27日随笔档案 - Rory's Blog

2006年12月27日

xstream是个好东西。对于配置文件的读取很方便。在mybog中我就用到了。不过今天打算用yupoo的api来做相册。发现xstream对于xmlnode的attribute解析支持不是那么的好。
对于这种节点格式的非常的简单

<result>
    <page>1</page>
    <pages>1</pages>
    <perpage>100</perpage>
    <total>19</total>
    <photos>
        <photo>
            <id>ff8080810fc8ac78010fd3f158d40a52</id>
            <owner>ff8080810f1a387b010f1a83d6530dfc</owner>
            <title>Gmail-2</title>
            <host>4</host>
            <dir>20061230</dir>
            <filename>231905_1463411198</filename>
        </photo>
    </photos>
</result>

简单的alias一下就可以读到值了

File file = new File("src/test/java/com/jdkcn/test/result.xml");
BufferedReader reader = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8"));
XStream stream = new XStream();
stream.alias("result", YupooResult.class);
stream.alias("photo",YupooPhoto.class);
YupooResult result = (YupooResult)stream.fromXML(reader);

可是Yupoo的api返回的xmlrpc的结果是这样的

这样就load不到值了。没法去mailist里面找答案，果然有人问。

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的文档。果然找到答案了。
自己写一个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);
    }
}

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



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

2007年1月18日更新。
这里感谢网友 Ivan Chen（西滨）的提示。原来新版的xstream可以简单的解决了。在1.2.1的doc里面找到了这个两个方法。

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

这两个方法都是从1.2开始支持的。
也不用自己写converter了。这样就可以了

        stream.alias("result", YupooResult.class);
        stream.useAttributeFor("page", Integer.class);
        stream.useAttributeFor("pages", Integer.class);
        stream.useAttributeFor("perpage", Integer.class);
        stream.useAttributeFor("total", Integer.class);
        stream.alias("photo", YupooPhoto.class);
        stream.useAttributeFor("id", String.class);
        stream.useAttributeFor("owner", String.class);
        stream.useAttributeFor("title", String.class);
        stream.useAttributeFor("host", String.class);
        stream.useAttributeFor("dir", String.class);
        stream.useAttributeFor("filename", String.class);

除经特别注明外,本文章版权归莫多泡泡所有.
署名,非商业用途,保持一致. somebody(莫多)

posted @ 2007-01-17 18:24 莫多阅读(7983) | 评论 (2) | 编辑收藏

又是乱码问题-Filter 配置也很重要

上周更新了一下myblog,添加了一个Filter，做统计访问用。可是后来发现出现乱码问题了。找了很久都没有找到问题。debug的时候看到 CharacterEncodingFilter确实是执行了。不过就是没有效果。执行之前是ISO-8859-1编码的，执行之后还是， CharacterEncodingFilter就没有起到作用。后来终于找到问题的原因了。原来是Filter配置先后顺序的原因。
刚开始的配置是这样的:

     < filter-mapping >
         < filter-name > requestCounterFilter </ filter-name >
         < url-pattern > *.jhtml </ url-pattern >
     </ filter-mapping >

     < filter-mapping >
         < filter-name > encodingFilter </ filter-name >
         < url-pattern > /dwr/* </ url-pattern >
     </ filter-mapping >

     < filter-mapping >
         < filter-name > encodingFilter </ filter-name >
         < url-pattern > *.jhtml </ url-pattern >
     </ filter-mapping >

     < filter-mapping >
         < filter-name > encodingFilter </ filter-name >
         < url-pattern > *.jsp </ url-pattern >
     </ filter-mapping >

先经过那个统计的filter然后再经过编码的filter。这样的话编码的filter就不起作用了。只要吧编码的filter放到最前面就没有问题了。改成这样就好。

     < filter-mapping >
         < filter-name > encodingFilter </ filter-name >
         < url-pattern > /dwr/* </ url-pattern >
     </ filter-mapping >

     < filter-mapping >
         < filter-name > encodingFilter </ filter-name >
         < url-pattern > *.jhtml </ url-pattern >
     </ filter-mapping >

     < filter-mapping >
         < filter-name > encodingFilter </ filter-name >
         < url-pattern > *.jsp </ url-pattern >
     </ filter-mapping >

     < filter-mapping >
         < filter-name > requestCounterFilter </ filter-name >
         < url-pattern > *.jhtml </ url-pattern >
     </ filter-mapping >

以后大家一定要注意啊。顺序问题也是很重要的。
除经特别注明外,本文章版权归莫多泡泡所有.
署名,非商业用途,保持一致. somebody(莫多)

posted @ 2006-12-27 10:37 莫多阅读(2679) | 评论 (3) | 编辑收藏

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