CODEWITHSUNDEEP
xml-parsingjaxb
Michael
Michael

Reputation: 2726

JAXB XmlJavaTypeAdapter unmarshal method not being called

I am trying to marshal/unmarshal a Color to XML. The JAXB project had example code for doing this exact thing via a XmlJavaTypeAdapter https://jaxb.java.net/guide/XML_layout_and_in_memory_data_layout.html.

The marshaling works fine and the output is what I expect:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<beanWithColor>
    <foreground>#ff0000ff</foreground>
    <name>CleverName</name>
</beanWithColor>

However, when trying to go from XML to object the unmarshal method is never called. Can anyone provide insight as to why? After it is unmarshalled foreground color is null and I have confirmed with my debugger that unmarshal is never being called:

BeanWithColor{foreground=null, name='CleverName'}

SCCE:

@XmlRootElement
public class BeanWithColor {
private String name;
private Color foreground;

public BeanWithColor() {

}

public BeanWithColor(Color foreground, String name) {
    this.foreground = foreground;
    this.name = name;
}

@XmlJavaTypeAdapter(ColorAdapter.class)
public Color getForeground() {
    return this.foreground;
}

public void setForeground(Color foreground) {
    this.foreground = foreground;
}

public String getName() {
    return name;
}

public void setName(String name) {
    this.name = name;
}

@Override
public String toString() {
    final StringBuilder sb = new StringBuilder("BeanWithColor{");
    sb.append("foreground=").append(foreground);
    sb.append(", name='").append(name).append('\'');
    sb.append('}');
    return sb.toString();
}

public static void main(String[] args) {
    BeanWithColor bean = new BeanWithColor(Color.blue, "CleverName");

    try {
        StringWriter writer = new StringWriter(1000);
        JAXBContext context = JAXBContext.newInstance(BeanWithColor.class);
        final Marshaller marshaller = context.createMarshaller();
        marshaller.marshal(bean, writer);
        System.out.println("Marshaled XML: " + writer);

        final Unmarshaller unmarshaller = context.createUnmarshaller();
        BeanWithColor beanWithColor = (BeanWithColor) unmarshaller.unmarshal(new StringReader(writer.toString()));
        System.out.println("beanWithColor = " + beanWithColor);
    } catch (JAXBException e) {
        e.printStackTrace();
    }

}

static class ColorAdapter extends XmlAdapter<String, Color> {
    public Color unmarshal(String s) {
        return Color.decode(s);
    }

    public String marshal(Color color) {
        return '#' + Integer.toHexString(color.getRGB());
    }
}
}

Upvotes: 1

Views: 2443

Answers (1)

bdoughan
bdoughan

Reputation: 148977

I suspect that XmlAdapter is being called for unmarshal but that the Color.decode method is failing (this is what happens when I debugged your code). 

Color.decode("#ff0000ff");

results in the following:

Exception in thread "main" java.lang.NumberFormatException: For input string: "ff0000ff"
    at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
    at java.lang.Integer.parseInt(Integer.java:461)
    at java.lang.Integer.valueOf(Integer.java:528)
    at java.lang.Integer.decode(Integer.java:958)
    at java.awt.Color.decode(Color.java:707)

You can set a ValidationEventHandler on the Unmarshaller to get a hook on all failures. By default a JAXB impl wouldn't report that problem.

The Fix

The ColorAdapter.marshal method needs to be fixed to return the correct value.

String rgb = Integer.toHexString(color.getRGB());
return "#" + rgb.substring(2, rgb.length());

Upvotes: 2

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