泽西岛无法解组java.lang.Number

Question

I have a generic (POJO-)container to share statistical data with clients:

@XmlRootElement
public class StatsSeries implements Serializable {

    private TreeMap<Date, Number> timeSeries;

    /* accessor methods */
}

Depending on the data, the server stores Long , Integer or Double in it, which is why I'm using abstract java.lang.Number .

Marshalling works fine, and hints indicating the concrete class are included in the data:

            "timeSeries": {
                "entry": [
                    {
                        "key": "2012-08-20T00:00:00Z", 
                        "value": {
                            "$": "24", 
                            "@type": "xs:long"
                        }
                    }, 
                    ....
                 ]
              }

Or in XML representation:

    <timeSeries>
      <entry>
        <key>2012-08-20T00:00:00Z</key>
        <value xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xs="http://www.w3.org/2001/XMLSchema" xsi:type="xs:long">24</value>
      </entry>
      ...
    </timeSeries>

When attempting to unmarshall this, I get an javax.xml.bind.UnmarshalException: Unable to create an instance of java.lang.Number .

I saw this question , but it doesn't help me. How can I annotate java.lang.Number ? Any other suggestions?

Update : Looking at JAXB-890 , I understand that it should be fixed either on JDK 1.7 or using com.sun.xml.bind:jaxb-impl:2.2.6 -- neither works for me.

Answer 1

Not sure this will work given type-erasure, but you might try annotating with XmlElementRef

    @XmlElementRef
    private TreeMap<Date, Number> timeSeries;

"when this annotation is used, the XML element name is derived from the instance of the type of the JavaBean property at runtime".

Failing that, see if this link helps .