JAXB 로 Map 데이터 다루기

쉽게 Java Beans ↔ XML 처리를 할 수 있는 JAXB 라이브러리를 통해서 java.util.Map 의 구현체 (HashMap)을
XML 화 처리하려고 하였습니다.

1차적으로 그냥 HashMap 형식으로 Marshaller 를 만들어서 처리를 하였으나...
Marshaller marshaller = JAXBContext.newInstance(HashMap.class).createMarshaller(); marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8"); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);

결과는

javax.xml.bind.MarshalException
 - with linked exception:
[com.sun.istack.internal.SAXException2: unable to marshal type "java.util.HashMap" as an element because it is missing an @XmlRootElement annotation]

안되는 것이지요...

그래서 클래스로 감싸서 처리해보았습니다.
ContentData.java
import java.io.StringReader; import java.io.StringWriter; import java.util.Map; import javax.xml.bind.JAXBContext; import javax.xml.bind.Marshaller; import javax.xml.bind.Unmarshaller; import javax.xml.bind.annotation.XmlAccessType; import javax.xml.bind.annotation.XmlAccessorType; import javax.xml.bind.annotation.XmlRootElement; @XmlAccessorType(XmlAccessType.FIELD) @XmlRootElement(name = "content") public class ContentData { private Map contentMap; public Map getContentMap() { return contentMap; } public void setContentMap(Map contentMap) { this.contentMap = contentMap; } private static Marshaller marshaller; private static Unmarshaller unmarshaller; public static String marshalling(ContentData contentData) { StringWriter writer = new StringWriter(); try { if (marshaller == null) { marshaller = JAXBContext.newInstance(ContentData.class).createMarshaller(); marshaller.setProperty(Marshaller.JAXB_ENCODING, "UTF-8"); marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true); } marshaller.marshal(contentData, writer); } catch (Exception e) { e.printStackTrace(); } return writer.toString(); } public static ContentData unmarshalling(String data) { ContentData contentData = null; StringReader reader = new StringReader(data); try { if (unmarshaller == null) { unmarshaller = JAXBContext.newInstance(ContentData.class).createUnmarshaller(); } contentData = (ContentData) unmarshaller.unmarshal(reader); } catch (Exception e) { e.printStackTrace(); } return contentData; } }

테스트는 아래와 같이 한 후 확인해보면...
ContentData contentData = new ContentData(); Map map = new HashMap(); map.put("abc", "abcd"); map.put("abc1", "abcd"); contentData.setContentMap(map); String data = ContentData.marshalling(contentData); System.out.println(data);

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<content>
    <contentMap>
        <entry>
            <key xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">abc</key>
            <value xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">abcd</value>
        </entry>
        <entry>
            <key xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">abc1</key>
            <value xsi:type="xs:string" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">abcd</value>
        </entry>
    </contentMap>
</content>

필요 없는 데이터가 길어져버렸습니다.


이러면 안되기에 JavaDoc 을 더 훑어본 후 @XmlJavaTypeAdapter 라는 것을 찾아내었습니다.
ContentData 클래스의 contentData 객체의 어노테이션을 추가합니다.
public class ContentData { @XmlJavaTypeAdapter(value=HashMapAdapter.class) private Map contentMap; ... }

HashMapAdapter.java
import java.util.ArrayList; import java.util.HashMap; import java.util.Iterator; import java.util.List; import java.util.Map; import javax.xml.bind.annotation.adapters.XmlAdapter; class HashMapAdapter extends XmlAdapter<KeyValuePair[], Map<String, String>> { public HashMapAdapter() { super(); } @Override public KeyValuePair[] marshal(Map<String, String> v) throws Exception { List<KeyValuePair> list = new ArrayList<KeyValuePair>(); for (Iterator<String> it = v.keySet().iterator(); it.hasNext(); ) { String key = it.next(); String value = v.get(key); list.add(new KeyValuePair(key, value)); } return list.toArray(new KeyValuePair[0]); } @Override public Map<String, String> unmarshal(KeyValuePair[] v) throws Exception { Map<String, String> contentMap = new HashMap<String, String>(); for (KeyValuePair pair : v) { contentMap.put(pair.getKey(), pair.getValue()); } return contentMap; } }
KeyValuePair.java
import javax.xml.bind.annotation.XmlAccessType; import javax.xml.bind.annotation.XmlAccessorType; import javax.xml.bind.annotation.XmlAttribute; @XmlAccessorType(XmlAccessType.FIELD) public class KeyValuePair { @XmlAttribute private String key; @XmlAttribute private String value; public KeyValuePair() { super(); } public KeyValuePair(String key, String value) { super(); this.key = key; this.value = value; } public String getKey() { return key; } public void setKey(String key) { this.key = key; } public String getValue() { return value; } public void setValue(String value) { this.value = value; } }


테스트를 해보았습니다.
ContentData contentData = new ContentData(); Map map = new HashMap(); map.put("abc", "abcd"); map.put("abc1", "abcd"); contentData.setContentMap(map); String data = ContentData.marshalling(contentData); System.out.println(data); ContentData contentData2 = ContentData.unmarshalling(data); System.out.println(contentData2.getContentMap());

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<content>
    <contentMap>
        <item value="abcd" key="abc"/>
        <item value="abcd" key="abc1"/>
    </contentMap>
</content>

{abc=abcd, abc1=abcd} 

Marshalling 도 잘되고 Unmarshalling 도 잘됩니다. ㅋㅋㅋ

원래 JAXB 는 JAX-WS 때문에 나온 거 같은데 요긴하게 잘 써먹고 있습니다.
자바랑 플렉스간의 연동시에도 JAXB 를 활용하면 좀더 편하게 처리를 할 수 있을 것 같아요 ㅋㅋㅋ