September 8, 2010

Processing Atom Feeds with JAXB

Atom is an XML format for representing web feeds.  A standard format allows reader applications to display feeds from different sources.  In this example we will process the Atom feed for this blog.


Demo

In this example we will use JAXB to convert the Atom XML feed corresponding to this blog to objects and then back to XML.

import java.io.InputStream;
import java.net.URL;
import javax.xml.bind.*;
import javax.xml.transform.stream.StreamSource;
import org.w3._2005.atom.FeedType;

public class Demo {

    public static void main(String[] args) throws Exception {
        JAXBContext jc = JAXBContext.newInstance("org.w3._2005.atom");

        Unmarshaller unmarshaller = jc.createUnmarshaller();
        URL url = new URL("http://bdoughan.blogspot.com/atom.xml");
        InputStream xml = url.openStream();
        JAXBElement<feedtype> feed = unmarshaller.unmarshal(new StreamSource(xml), FeedType.class);
        xml.close();

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

}

JAXB Model

The following model was generated by the schema to Java compiler (XJC). I have omitted the get/set methods and comments to save space.

xjc -d generated http://www.kbcafe.com/rss/atom.xsd.xml

package-info

@XmlSchema(
        namespace = "http://www.w3.org/2005/Atom",
        elementFormDefault = XmlNsForm.QUALIFIED)
@XmlAccessorType(XmlAccessType.FIELD)
package org.w3._2005.atom;

import javax.xml.bind.annotation.*;

CategoryType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "categoryType")
public class CategoryType {
    @XmlAttribute(required = true)
    protected String term;

    @XmlAttribute
    @XmlSchemaType(name = "anyURI")
    protected String scheme;

    @XmlAttribute
    protected String label;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

Content Type

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "contentType", propOrder = {"content"})
public class ContentType {
    @XmlMixed
    @XmlAnyElement(lax = true)
    protected List<Object> content;

    @XmlAttribute
    protected String type;

    @XmlAttribute
    @XmlSchemaType(name = "anyURI")
    protected String src;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

DateTimeType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.datatype.XMLGregorianCalendar;
import javax.xml.namespace.QName;

@XmlType(name = "dateTimeType", propOrder = {"value"})
public class DateTimeType {
    @XmlValue
    @XmlSchemaType(name = "dateTime")
    protected XMLGregorianCalendar value;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

EntryType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "entryType", propOrder = {"authorOrCategoryOrContent"})
public class EntryType {
    @XmlElementRefs({
        @XmlElementRef(name = "id", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "rights", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "summary", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "title", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "author", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "source", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "updated", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "category", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "content", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "published", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "contributor", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "link", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class)
    })
    @XmlAnyElement(lax = true)
    protected List<Object> authorOrCategoryOrContent;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

FeedType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "feedType", propOrder = {"authorOrCategoryOrContributor"})
public class FeedType {
    @XmlElementRefs({
        @XmlElementRef(name = "link", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "updated", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "category", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "rights", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "contributor", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "title", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "id", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "generator", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "icon", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "subtitle", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "author", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "entry", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "logo", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class)
    })
    @XmlAnyElement(lax = true)
    protected List<Object> authorOrCategoryOrContributor;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

GeneratorType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "generatorType", propOrder = {"value"})
public class GeneratorType {
    @XmlValue
    protected String value;

    @XmlAttribute
    @XmlSchemaType(name = "anyURI")
    protected String uri;

    @XmlAttribute
    protected String version;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

IconType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "iconType", propOrder = {"value"})
public class IconType {
    @XmlValue
    @XmlSchemaType(name = "anyURI")
    protected String value;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

IdType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "idType", propOrder = {"value"})
public class IdType {
    @XmlValue
    @XmlSchemaType(name = "anyURI")
    protected String value;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

LinkType

package org.w3._2005.atom;

import java.math.BigInteger;
import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "linkType", propOrder = {"content"})
public class LinkType {
    @XmlValue
    protected String content;

    @XmlAttribute(required = true)
    @XmlSchemaType(name = "anyURI")
    protected String href;

    @XmlAttribute
    protected String rel;

    @XmlAttribute
    protected String type;

    @XmlAttribute
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "NMTOKEN")
    protected String hreflang;

    @XmlAttribute
    protected String title;

    @XmlAttribute
    @XmlSchemaType(name = "positiveInteger")
    protected BigInteger length;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

LogoType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "logoType", propOrder = {"value"})
public class LogoType {
    @XmlValue
    @XmlSchemaType(name = "anyURI")
    protected String value;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

PersonType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "personType", propOrder = {"nameOrUriOrEmail"})
public class PersonType {
    @XmlElementRefs({
        @XmlElementRef(name = "email", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "name", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "uri", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class)
    })
    @XmlAnyElement(lax = true)
    protected List<Object> nameOrUriOrEmail;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

SourceType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.JAXBElement;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "sourceType", propOrder = {"authorOrCategoryOrContributor"})
public class SourceType {
    @XmlElementRefs({
        @XmlElementRef(name = "updated", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "category", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "subtitle", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "logo", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "generator", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "icon", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "title", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "id", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "author", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "contributor", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "link", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class),
        @XmlElementRef(name = "rights", namespace = "http://www.w3.org/2005/Atom", type = JAXBElement.class)
    })
    @XmlAnyElement(lax = true)
    protected List<Object> authorOrCategoryOrContributor;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

TextType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "textType", propOrder = {"content"})
public class TextType {
    @XmlMixed
    @XmlAnyElement(lax = true)
    protected List<Object> content;

    @XmlAttribute
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    protected String type;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

UriType

package org.w3._2005.atom;

import java.util.*;
import javax.xml.bind.annotation.*;
import javax.xml.bind.annotation.adapters.*;
import javax.xml.namespace.QName;

@XmlType(name = "uriType", propOrder = {"value"})
public class UriType {
    @XmlValue
    @XmlSchemaType(name = "anyURI")
    protected String value;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlSchemaType(name = "anyURI")
    protected String base;

    @XmlAttribute(namespace = "http://www.w3.org/XML/1998/namespace")
    @XmlJavaTypeAdapter(CollapsedStringAdapter.class)
    @XmlSchemaType(name = "language")
    protected String lang;

    @XmlAnyAttribute
    private Map<QName, String> otherAttributes = new HashMap<QName, String>();
}

ObjectFactory

Omitted due to its length.

2 comments:

  1. What happens if I put an entry into the @XmlAnyAttribute map for an attribute which is already explicitly bound, and then marshal the stuff? I believe the current behaviour of both MOXy and the standard implementation is wrong, as non well-formed XML is output. See this discussion.

    ReplyDelete