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JAXB / MOXy: Do not call the XmlElementWrapper setter when an element is missing?

I have a set setter in a class that annotates with both @XmlElementWrapper (name = "foos") and @XmlElement (name = "foo").

When I am unmarshall XML that has no <foos> </foos> or <foo / "> elements, the empty list is called and called. Is there any way to get the following ?:

  • If there is no <foos / ">, do not call the installer. Or, if the calling call should be called, skip null.
  • When <foos / "> is present but empty, pass the empty set to the installer.
  • When <foos> has one or more child <foo / "> elements, pass the filled list.
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4

XmlAdapter :

input1.xml

, . , , null.

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <child/>
</root>

input2.xml

, , .

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <child>
        <foos/>
    </child>
</root>

input3.xml

 , .

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <child>
        <foos>
             <foo>Hello World</foo>
       </foos>
   </child>
</root>

Root

import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter;

@XmlRootElement
public class Root {

    private Child child;

    @XmlJavaTypeAdapter(ChildAdapter.class)
    public Child getChild() {
        return child;
    }

    public void setChild(Child child) {
        this.child = child;
    }

}


import java.util.List;

public class Child {

    private List<String> strings;

    public List<String> getStrings() {
        return strings;
    }

    public void setStrings(List<String> strings) {
        System.out.println("setStrings");
        this.strings = strings;
    }

}

ChildAdapter

import java.util.ArrayList;
import java.util.List;

import javax.xml.bind.annotation.adapters.XmlAdapter;

public class ChildAdapter extends XmlAdapter<ChildAdapter.AdaptedChild, Child> {

    public static class AdaptedChild {
        public Foos foos;
    }

    public static class Foos {
        public List<String> foo;
    }

    @Override
    public Child unmarshal(AdaptedChild adaptedChild) throws Exception {
        Child child = new Child();
        Foos foos = adaptedChild.foos;
        if(null != foos) {
            List<String> foo = foos.foo;
            if(null == foo) {
                child.setStrings(new ArrayList<String>());
            } else {
                child.setStrings(foos.foo);
            }
        }
        return child;
    }

    @Override
    public AdaptedChild marshal(Child child) throws Exception {
        AdaptedChild adaptedChild = new AdaptedChild();
        List<String> strings = child.getStrings();
        if(null != strings) {
            Foos foos = new Foos();
            foos.foo = strings;
            adaptedChild.foos = foos;
        }
        return adaptedChild;
    }

}

Demo

import java.io.File;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.Marshaller;
import javax.xml.bind.Unmarshaller;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance(Root.class);

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        Marshaller marshaller = jc.createMarshaller();
        marshaller.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true);
        Object o;

        o = unmarshaller.unmarshal(new File("input1.xml"));
        marshaller.marshal(o, System.out);

        o = unmarshaller.unmarshal(new File("input2.xml"));
        marshaller.marshal(o, System.out);

        o = unmarshaller.unmarshal(new File("input3.xml"));
        marshaller.marshal(o, System.out);
    }

}


<?xml version="1.0" encoding="UTF-8"?>
<root>
   <child/>
</root>
setStrings
<?xml version="1.0" encoding="UTF-8"?>
<root>
   <child>
      <foos/>
   </child>
</root>
setStrings
<?xml version="1.0" encoding="UTF-8"?>
<root>
   <child>
      <foos>
         <foo>Hello World</foo>
      </foos>
   </child>
</root>
+2

, , :

public class ListOfFooAdapter extends XmlAdapter<ListOfFooAdapter.Adapted, List<Foo>> {
    @XmlRootElement(name = "foos")
    public static class Adapted {
        public List<Foo> foo;
    }

    @Override
    public List<Foo> unmarshal(Adapted adapted) throws Exception {
        return adapted.foo;
    }

    @Override
    public Adapted marshal(List<Foo> foo) throws Exception {
    if (null == foo) {
            return null;
        } else {
            Adapted adapted = new Adapted();
            adapted.foo = foo;
            return adapted;
        }
    }
}

... unmarshall , XML.

:

@XmlJavaTypeAdapter(ListOfFooAdapter.class)
public List<Foo> getFoos() {
    ...
}

public void setFoos(List<Foo> l) {
    ...
}
+1

. , .

, , - , JAXB JDK 6, XML .

, JAXB , , , unmarshalling:

@XmlElementWrapper(name = "foos")
@XmlElement(name = "foo")
public void setFoos(List<Foo> newFoos) {
    this.foos.clear();
    this.foos.addAll(newFoos);
}


@XmlElementWrapper(name = "foos")
@XmlElement(name = "foo")
public void setFoos(List<Foo> newFoos) {
    this.foos = newFoos;
}

. , - , , .

, , JAXB, , , ConcurrentModificationException, , .

+1

You can put all your logic in methods beforeUnmarshall, afterUnmarshallor Unmarshallerlistener, and it will be executed when the cancellation cancel procedure is completed.

See fooobar.com/questions/297596 / ... for more details .

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