JAXB unmarshal XML elements to HashMap

Question

I found a lot of articles that describe how to unmarshal a sequence of XML elements to a HashMap as long as they are within a \"parent\" element. However, I do not get this to w

Answer 1

Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB (JSR-222) expert group.

JAXB will treat each object relationship with a nesting relationship. Map is treated like an Object instead of a Collection so this is why you are getting the behaviour that you are seeing.

MOXy has an XPath based mapping extension called @XmlPath that could be used for this use case.

package com.foo.conf;

import java.util.Map;

import javax.xml.bind.annotation.XmlElement;
import javax.xml.bind.annotation.XmlRootElement; 
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;
import org.eclipse.persistence.oxm.annotations.XmlPath;

@XmlRootElement(name="checks")
public class Checks {       
    @XmlJavaTypeAdapter(ChecksAdapter.class)
    @XmlPath(".")
    public Map<String, Check> checkMap;     
}

For More Information

• http://blog.bdoughan.com/2010/07/xpath-based-mapping.html
• http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html

Answer 2

How are you generaing the JAXB classes? I am not sure what exactly are you trying to do but the below very simple code works for me ..

    JAXBContext jc = JAXBContext.newInstance(ChecksType.class);

    Unmarshaller unmarshaller = jc.createUnmarshaller();
    ChecksType chksType = (ChecksType) unmarshaller.unmarshal(new File("/path/to/xml"));

    Marshaller marshaller = jc.createMarshaller();
    marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
    marshaller.marshal(chksType, System.out);

    System.err.println(chksType.getCheck().get(0).getKey());

    for (CheckType checkType : chksType.getCheck()) {
        System.out.println("key = " + checkType.getKey() + ", " + checkType);
    }

and here is my JAXB generated classes .. ChecksType (Root element)

   @XmlAccessorType(XmlAccessType.FIELD)
   @XmlType(name = "checksType", propOrder = { "check" })
   @XmlRootElement(name = "checks")
   public class ChecksType {

         @XmlElement(required = true)
         protected List<CheckType> check;


        public List<CheckType> getCheck() {
           if (check == null) {
             check = new ArrayList<CheckType>();
           }
           return this.check;
        }

   }

And checkType (the child)

    @XmlAccessorType(XmlAccessType.FIELD)
    @XmlType(name = "checkType")
    public class CheckType {

         @XmlAttribute(name = "key")
         protected String key;


         public String getKey() {
            return key;
         }


         public void setKey(String value) {
            this.key = value;
         }

   }