JAXBElement in WebService data structure

Question

I am learning JAX-WS and i also was introduced with JAXB. I can use it to (un)marshal java(xml) to xml(java). But what is the purpose of this line then i generated my WS data with Apache CXF:

@XmlElementRef(name = "Id", namespace = "External.Test", type = JAXBElement.class, required = false)
    protected JAXBElement<String> id;

Why it can't be just String id instead of JAXBElement<String> id ?
How can I convert request data (let's say java POJO) into structure like this above? (I am talking about mapping from POJO to this exposed WS structure with fields wrapped into JAXBElements)

It can't just be a string because you are dealing with a web service. Web services are used via different languages, and some languages handle strings differently. Take a look at this http://stackoverflow.com/questions/14489306/parameter-jaxbelement-string — j.con, Sep 30 '14 at 19:41
@j.con This has nothing to do with string handling in different languages. — lexicore, Sep 30 '14 at 21:34
@lexicore oh yea? Try to consume an `int` from a java web service in C# when the `int` is null. C# does not allow `int` to be null, only a `int?` that is why a standard wrapper is used... — j.con, Oct 01 '14 at 12:40
@j.con I repeat, `@XmlElementRef` or `JAXBElement` vs. `String` has nothing to do with string handling in different languages. This depends on how the originating schema is defined. The problem you're addressing is the nillability. Well, yes, `nillable="true"` is ONE of the reasons for `@XmlElementRef`, but it is not the only one. — lexicore, Oct 01 '14 at 12:54

score 1 · Accepted Answer · edited May 23 '17 at 10:26

1.- This structure is used depending on how did you define your schema. For instance, if you use a sustitution group. See this answer for more info.

2.- Here some code that might help you: Let´s say that you POJO defines a structure like this:

public JAXBElement<?> getObjectData() {
    return objectData;
}

Then, when you unmarshalled the request that you have received, is filled with a String that you want to recover:

JAXBElement<String> rncElem = (JAXBElement<String>) dataContainer.getObjectData();
return rncElem.getValue();

JAXBElement in WebService data structure

1 Answers1