JAXB- @XmlMixed usage for reading @XmlValue and @XmlElement

I’ll try to answer your question with an example:

input.xml

We will use the following XML document for this example. The root element has mixed content. Having mixed conent means that text nodes can appear mixed in with the elements. Since more than one text node can appear a unary property isn’t a good fit.

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

Demo

The following code will be used in to read in the XML to object form and then write it back to XML.

package forum10940267;

import java.io.File;
import javax.xml.bind.*;

public class Demo {

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

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        File xml = new File("src/forum10940267/input.xml");
        Root root = (Root) unmarshaller.unmarshal(xml);

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

}

USE CASE #1 – One List to Hold Mixed Content

@XmlMixed is most often used to with another annotation, so that the resulting List contains both element and text content. One advantage of this is that order is maintained so that the document can be round tripped.

package forum10940267;

import java.util.*;
import javax.xml.bind.annotation.*;

@XmlRootElement
public class Root {

    private List<Object> mixedContent = new ArrayList<Object>();

    @XmlElementRef(name="root", type=Root.class)
    @XmlMixed
    public List<Object> getMixedContent() {
        return mixedContent;
    }

    public void setMixedContent(List<Object> mixedContent) {
        this.mixedContent = mixedContent;
    }

}

Output

The output matches the input.

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<root>
    <root/>
    Hello
    <root/>
    World
    <root/>
</root>

USE CASE #2 – Separate List for Mixed Content

You can can also introduce a separate list property for the text content.

package forum10940267;

import java.util.*;
import javax.xml.bind.annotation.*;

@XmlRootElement
public class Root {

    private List<Object> mixedContent = new ArrayList<Object>();
    private List<String> text;

    @XmlElementRef(name="root", type=Root.class)
    public List<Object> getMixedContent() {
        return mixedContent;
    }

    public void setMixedContent(List<Object> mixedContent) {
        this.mixedContent = mixedContent;
    }

    @XmlMixed
    public List<String> getText() {
        return text;
    }

    public void setText(List<String> text) {
        this.text = text;
    }

}

Output

The output no longer matches the input.

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

    Hello

    World

</root>

USE CASE #3 – String Property for Text Content

Since text nodes can occur multiple times in mixed content, a non-List property isn’t a good fit and it appears as though the @XmlMixed annotation is being ignored.

package forum10940267;

import java.util.*;
import javax.xml.bind.annotation.*;

@XmlRootElement
public class Root {

    private List<Object> mixedContent = new ArrayList<Object>();
    private String text;

    @XmlElementRef(name="root", type=Root.class)
    public List<Object> getMixedContent() {
        return mixedContent;
    }

    public void setMixedContent(List<Object> mixedContent) {
        this.mixedContent = mixedContent;
    }

    @XmlMixed
    public String getText() {
        return text;
    }

    public void setText(String text) {
        this.text = text;
    }

}

Output

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