Use Jakarta Digester or JAXB?

Question

Given a scenario: I have my own system's object structure. Now there are more than one XML sources I have to map to my java classes. And there is no need to convert Java object back into XML.

What's your suggestion for me to use Digester or JAXB? Currently I lean to use Digester, because I can specify XML path for each XML source to the same object method call, and Digester seems to be easier to maintain. Although JAXB has good design to marshal/unmarshal java and XML, but I think it is too complicated, xml schema is needed for each xml-java mapping, right?

I think both Digester or JAXB has their mission to fit different usage scenario, so need your advice to help me decide one of them. Thanks a lot.

score 4 · Answer 1 · answered Jan 07 '11 at 08:54

I think you may have a skewed view of JAXB. It can be complicated, if you choose to make it so, but it can also be extremely simple. For example, you can bind an entire XML document onto an object graph with only a single annotation.

Also, the schema thing is a red herring. JAXB can generate java code from an XML Schema, but that's just a convenience for cases where you have a schema. If you don't, then ignore that part. You can annotate your class model by hand, it's very easy.

Digester, on the other hand, is harder to maintain (in my opinion), since you have to muck about with path expressions ion addition to your class model.

Thanks a lot, I think I should spend more time with JAXB. – Matt Jan 07 '11 at 15:28 — Matt, Jan 07 '11 at 15:28

score 3 · Accepted Answer · answered Jan 07 '11 at 14:14

An advantage of JAXB is that it is a spec (JSR-222) with multiple implementations: Metro, EclipseLink MOXy, JaxMe. This avoids the problem of vendor lock in.

XPath Based Mapping

The EclipseLink JAXB (MOXy) has an extension to support XPath based mapping (I'm the tech lead).

package blog.geocode;

import javax.xml.bind.annotation.XmlRootElement;
import javax.xml.bind.annotation.XmlType;

import org.eclipse.persistence.oxm.annotations.XmlPath;

@XmlRootElement(name="kml")
@XmlType(propOrder={"country", "state", "city", "street", "postalCode"})
public class Address {

    @XmlPath("Response/Placemark/ns:AddressDetails/ns:Country/ns:AdministrativeArea/ns:SubAdministrativeArea/ns:Locality/ns:Thoroughfare/ns:ThoroughfareName/text()")
    private String street;

    @XmlPath("Response/Placemark/ns:AddressDetails/ns:Country/ns:AdministrativeArea/ns:SubAdministrativeArea/ns:Locality/ns:LocalityName/text()")
    private String city;

    @XmlPath("Response/Placemark/ns:AddressDetails/ns:Country/ns:AdministrativeArea/ns:AdministrativeAreaName/text()")
    private String state;

    @XmlPath("Response/Placemark/ns:AddressDetails/ns:Country/ns:CountryNameCode/text()")
    private String country;

    @XmlPath("Response/Placemark/ns:AddressDetails/ns:Country/ns:AdministrativeArea/ns:SubAdministrativeArea/ns:Locality/ns:PostalCode/ns:PostalCodeNumber/text()")
    private String postalCode;

}

Multiple XML Sources

To apply multiple XML representations to an object model you can leverage MOXy's XML metadata. This is another extension to the JAXB standard. An example file looks like:

<?xml version="1.0"?>
<xml-bindings
    xmlns="http://www.eclipse.org/eclipselink/xsds/persistence/oxm"
    package-name="blog.bindingfile">
    <xml-schema
        namespace="http://www.example.com/customer"
        element-form-default="QUALIFIED"/>
    <java-types>
        <java-type name="Customer">
            <xml-root-element/>
            <xml-type prop-order="firstName lastName address phoneNumbers"/>
            <java-attributes>
                <xml-element java-attribute="firstName" name="first-name"/>
                <xml-element java-attribute="lastName" name="last-name"/>
                <xml-element java-attribute="phoneNumbers" name="phone-number"/>
            </java-attributes>
        </java-type>
        <java-type name="PhoneNumber">
            <java-attributes>
                <xml-attribute java-attribute="type"/>
                <xml-value java-attribute="number"/>
            </java-attributes>
        </java-type>
    </java-types>
</xml-bindings>

For more information:

score 1 · Answer 3 · answered Jan 07 '11 at 09:39

1

Maybe off topic: I've abandonded digester in favor of xstream. Maybe have a look

answered Jan 07 '11 at 09:39

mtraut

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Check out: http://bdoughan.blogspot.com/2010/10/how-does-jaxb-compare-to-xstream.html – bdoughan Jan 07 '11 at 14:03
1

@Blaise: I really don't like XStream. It's buggy, slow and the API is butt-ugly. Handy for trivial applications, though. – skaffman Jan 07 '11 at 14:32
XStream is only useful as a non-binary replacement for Data[Input|Output]Stream. If you end up needing to customise the XML at all, you will soon wish you had stuck with Digester or JAXB. – Recurse Mar 18 '13 at 01:23
I actually always loved XStream for storing/retrieving object graphs in files, and have used it successfully in several non-trivial products. It also has the ability to [read/write in a binary format](https://x-stream.github.io/javadoc/com/thoughtworks/xstream/io/binary/package-summary.html). – voxoid Mar 17 '16 at 03:18

Use Jakarta Digester or JAXB?

3 Answers3