用XStream转换复杂XML

用XStream序列化对象，其中有Map类型的字段，结果不让人满意：

1.<ExtractResult>  
2. <dataRecords>  
3.   <DataRecord>  
4.     <properties>  
5.       <property>  
6.         <string>region</string>  
7.         <string>非洲中东</string>  
8.       </property>  
9.       <property>  
10.         <string>routeReference</string>  
11.         <string>首都机场集合，搭乘土耳其航空直飞伊斯坦布尔，夜宿机上。</string>  
12.       </property>  
13.       <property>  
14.         <string>routeDays</string>  
15.         <string>10</string>  
16.       </property>  
17.       <property>  
18.         <string>price</string>  
19.         <string>￥13500起</string>  
20.       </property>  
21.       <property>  
22.         <string>subject</string>  
23.         <string>常规</string>  
24.       </property>  
25.       <property>  
26.         <string>dayOfBookingExpired</string>  
27.         <string>2010-02-01</string>  
28.       </property>  
29.       <property>  
30.         <string>departure</string>  
31.         <string>北京</string>  
32.       </property>  
33.       <property>  
34.         <string>dayOfDeparture</string>  
35.         <string>2010-02-10</string>  
36.       </property>  
37.       <property>  
38.         <string>title</string>  
39.         <string>[团队游]埃及土耳其10日千年文明之旅(春节)</string>  
40.       </property>  
41.     </properties>  
42.   </DataRecord>  
43. </dataRecords>  
44.</ExtractResult>  

其中的key和value被序列化成：

1.<string>region</string>  
2.<string>非洲中东</string>

我比较想要的结果是
<property key="region" value="非洲中东"/>

查看了XStream的文档，可以通过自定义Converter来转换，经过尝试，只需要很简单的步骤就可以完成：

1.import java.util.HashMap;   
2.import java.util.Hashtable;   
3.import java.util.Iterator;   
4.import java.util.Map;   
5.import java.util.Map.Entry;   
6.  
7.import com.thoughtworks.xstream.converters.MarshallingContext;   
8.import com.thoughtworks.xstream.converters.UnmarshallingContext;   
9.import com.thoughtworks.xstream.converters.collections.AbstractCollectionConverter;   
10.import com.thoughtworks.xstream.io.ExtendedHierarchicalStreamWriterHelper;   
11.import com.thoughtworks.xstream.io.HierarchicalStreamReader;   
12.import com.thoughtworks.xstream.io.HierarchicalStreamWriter;   
13.import com.thoughtworks.xstream.mapper.Mapper;   
14.  
15./**  
16. * @author fuliang  
17. *   
18. */  
19.public class MapCustomConverter extends AbstractCollectionConverter {   
20.  
21.    /**  
22.     * @param mapper  
23.     */  
24.    public MapCustomConverter(Mapper mapper) {   
25.        super(mapper);   
26.    }   
27.  
28.    public boolean canConvert(Class type) {   
29.        return type.equals(HashMap.class)   
30.                || type.equals(Hashtable.class)   
31.                || type.getName().equals("java.util.LinkedHashMap")   
32.                || type.getName().equals("sun.font.AttributeMap") // Used by java.awt.Font in JDK 6   
33.                ;   
34.    }   
35.  
36.    public void marshal(Object source, HierarchicalStreamWriter writer, MarshallingContext context) {   
37.        Map map = (Map) source;   
38.        for (Iterator iterator = map.entrySet().iterator(); iterator.hasNext();) {   
39.            Entry entry = (Entry) iterator.next();   
40.            ExtendedHierarchicalStreamWriterHelper.startNode(writer, "property", Entry.class);   
41.  
42.            writer.addAttribute("key",  entry.getKey().toString());   
43.            writer.addAttribute("value", entry.getValue().toString());   
44.            writer.endNode();   
45.        }   
46.    }   
47.  
48.    public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext context) {   
49.        Map map = (Map) createCollection(context.getRequiredType());   
50.        populateMap(reader, context, map);   
51.        return map;   
52.    }   
53.  
54.    protected void populateMap(HierarchicalStreamReader reader, UnmarshallingContext context, Map map) {   
55.        while (reader.hasMoreChildren()) {   
56.            reader.moveDown();   
57.            Object key = reader.getAttribute("key");   
58.            Object value = reader.getAttribute("value");   
59.            map.put(key, value);   
60.            reader.moveUp();   
61.        }   
62.    }   
63.}  

然后这么使用：

1.XStream xStream = new XStream();   
2.xStream.registerConverter(new MapCustomConverter(new DefaultMapper(XmlOutputFormatter.class.getClassLoader())));   
3.xStream.alias("DataRecord", ExtractDataRecord.class);   
4.xStream.alias("ExtractResult", ExtractResult.class);   
5.xStream.alias("property", Entry.class);   
6.return xStream.toXML(extractResult);  

序列化后的结果很漂亮：

1.<ExtractResult>   
2.  <dataRecords>   
3.    <DataRecord>   
4.      <properties>   
5.        <property key="region" value="港澳"/>   
6.        <property key="routeReference" value="搭乘国际航班直飞桃园国际机场，办理相关手续后，前往用晚餐。前往酒店入住休息。"/>   
7.        <property key="routeDays" value="8"/>   
8.        <property key="price" value="￥5680起"/>   
9.        <property key="subject" value="常规"/>   
10.        <property key="dayOfBookingExpired" value="2010-01-15"/>   
11.        <property key="departure" value="北京"/>   
12.        <property key="dayOfDeparture" value="2010-01-25"/>   
13.        <property key="title" value="[团队游]台湾8日宝岛乡情之旅"/>   
14.      </properties>   
15.    </DataRecord>   
16.  </dataRecords>   
17.</ExtractResult> 

针对标签里面直接使用值的xml，比如

<IDS>
      <ID>1234534</ID>
      <ID>1111111111</ID>
  </IDS>
还有节点既有属性又有值的xml，比如

<INPUT>
  <RAW_SQL TYPE="PERSON">select id from person</RAW_SQL>
</INPUT>

需要一个转换器来转换，转换器代码如下：

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 com.zhhy.server.beans.RawSQL;

public class RawSQLConverter implements Converter {

 @SuppressWarnings("rawtypes")
 public boolean canConvert(Class clazz) {
  return clazz.equals(RawSQL.class);
 }

 public void marshal(Object value, HierarchicalStreamWriter writer, MarshallingContext acontext) {
  RawSQL rawSQL = (RawSQL) value;
  if (rawSQL != null) {
   if (null != rawSQL.getType()) {
    writer.addAttribute("TYPE", rawSQL.getType());
   }
   writer.setValue(rawSQL.getRawSql() == null ? "" : rawSQL.getRawSql());
  }

 }

 public Object unmarshal(HierarchicalStreamReader reader, UnmarshallingContext arg1) {
  RawSQL rawSql = new RawSQL();
  String type = reader.getAttribute("TYPE");
  rawSql.setType(type);

  String value = reader.getValue();

  rawSql.setRawSql(value);

  return rawSql;

 }

}

类的annotation配置如下：

@XStreamAlias("RAW_SQL")
@XStreamConverter(RawSQLConverter.class)
public class RawSQL {
 @XStreamAsAttribute
 @XStreamAlias("TYPE")
 private String type;

 private String rawSql;

 下面省略了getter和setter方法
}

后记：（2012-05-18日添加）

如果对象中定义的类型与实际类型不一致，比如定义的是Object类型，但是实际初始化的对象是其他类型，转换出来的xml文件都会加上class="实际类型"属性，举例：<PERSON class="PERSON">...</PERSON>

有两种方法去掉这个属性

1， xstream.alias("field name", Interface.class, ActualClassToUse.class);
2， xstream.aliasSystemAttribute(null, "class");

我选择用后面一种，这样会把所有class属性去掉，如果只去掉某些类的这个多余的属性，用第一种方式即可。

评论

2 楼 nanjiwubing123 2017-10-18  

long3ok 写道

你好 XmlOutputFormatter 请问这个类是在什么包里面的？

对的，XmlOutputFormatter 是什么鬼？

1 楼 long3ok 2016-12-06  

你好 XmlOutputFormatter 请问这个类是在什么包里面的？