Using the Rome Java API to access metadata fields

问题

I've been using the Rome API to parse data from an XML feed pretty successfully so for, but have run in to a bit of a snag.

Given the following snippet of XML:

<entry>
<id>uniqueId</id>
<updated>2008-11-05T01:32:35Z</updated>
<mm:status xmlns:mm="http://contentprovider.com&quot; available="true"/>
<title>Title</title>
...
...
</entry>

Using the SyndEntryImpl class I'm able to use its standard methods (getTitle, getPublishedDate, etc) to pull the title, id, updated date, etc, but havent figured out a way to get the metadata tag (<mm:status ...).

Getting a string representation of the feed entry would be an acceptable solution as I'd be able to use string functions to retrieve the information, but even with that I havent found an easy method.

Has anyone run in to this in the past?

Thanks.

回答1:

Here is the raw classes from our code without much explanation (but it is late here!). This parses elements:

import com.sun.syndication.io.ModuleGenerator;
import com.sun.syndication.io.impl.DateParser;
import com.sun.syndication.feed.module.Module;

import java.util.Collections;
import java.util.Set;
import java.util.HashSet;

import org.jdom.Element;
import org.jdom.Namespace;

/**
 * Generates mp content in atom.
 */
public class ModuleGenerator implements ModuleGenerator {

    private static final Namespace NAMESPACE = Namespace.getNamespace("mp", Module.URI);
    private static final Set<Namespace> NAMESPACES;

    static {
        Set<Namespace> namespaces = new HashSet<Namespace>();
        namespaces.add(NAMESPACE);
        NAMESPACES = Collections.unmodifiableSet(namespaces);
    }

    public String getNamespaceUri() {
        return Module.URI;
    }

    public Set<Namespace> getNamespaces() {
        return NAMESPACES;
    }

    public void generate(Module module, Element element) {
        Module myModule = (Module) module;
        if (myModule.getStartDate() != null) {
            Element myElement = new Element("startDate", NAMESPACE);
            myElement.setText(DateParser.formatW3CDateTime(myModule.getStartDate()));
            element.addContent(myElement);
        }
        if (myModule.getEndDate() != null) {
            Element myElement = new Element("endDate", NAMESPACE);
            myElement.setText(DateParser.formatW3CDateTime(myModule.getEndDate()));
            element.addContent(myElement);
        }
    }
}

import com.sun.syndication.feed.module.Module;

import java.util.Date;

/**
 * Module for mp atom extension.
 */
public interface Module extends Module {
    public static final String URI = "http://www.mp.com/namespace";

    public Date getStartDate();
    public void setStartDate(Date date);

    public Date getEndDate();
    public void setEndDate(Date date);
}

public class ModuleImpl extends ModuleImpl implements Module {

    private Date startDate;
    private Date endDate;

    public ModuleImpl() {
        super(Module.class, Module.URI);
    }

    @Override
    public Class getInterface() {
        return Module.class;
    }

    @Override
    public void copyFrom(Object obj) {
        Module module = (Module) obj;
        setStartDate(module.getStartDate());
        setEndDate(module.getEndDate());
    }

    @Override
    public Date getStartDate() {
        return startDate;
    }

    @Override
    public void setStartDate(Date date) {
        startDate = date;
    }

    @Override
    public Date getEndDate() {
        return endDate;
    }

    @Override
    public void setEndDate(Date date) {
        endDate = date;
    }

    @Override
    public String toString() {
        return "ModuleImpl{" +
                "startDate=" + startDate +
                ", endDate=" + endDate +
                '}';
    }
}

package com.mp.core.iomanagement.contentanalyzers.modules;

import java.util.Date;

import org.jdom.Element;
import org.jdom.Namespace;

import com.sun.syndication.feed.module.Module;
import com.sun.syndication.io.ModuleParser;
import com.sun.syndication.io.impl.DateParser;

/**
 * Parses mp content from atom.
 */
public class ModuleParser implements ModuleParser {

    public String getNamespaceUri() {
        return Module.URI;
    }

    public Module parse(Element element) {
        Namespace myNamespace = Namespace.getNamespace(Module.URI);
        Module module = null;
        Date start = null;
        Date end = null;
        final Element startChild = element.getChild("startDate", myNamespace);
        if (startChild!=null) {
            start = DateParser.parseDate(startChild.getText());
        }
        final Element endChild = element.getChild("endDate", myNamespace);
        if (endChild!=null) {
            end = DateParser.parseDate(endChild.getText());
        }

        if (start!=null || end!=null) {
            module = new ModuleImpl();
            module.setStartDate(start);
            module.setEndDate(end);
        }
        return module;
    }
}

rome.properties:

atom_1.0.item.ModuleParser.classes=\
com.mp.core.iomanagement.contentanalyzers.modules.ModuleParser

atom_1.0.item.ModuleGenerator.classes=\
com.mp.core.iomanagement.contentanalyzers.modules.ModuleGenerator

回答2:

If you're not already using it, v1.0RC1 has several parsing fixes. Maybe try upgrading?

回答3:

I just couldn't make the module approach work. Simply the module object wasn't there. Either at the feed or entry level. Luckily the method feed/entry .getForeignMarkup() did work for me.

来源：https://stackoverflow.com/questions/342619/using-the-rome-java-api-to-access-metadata-fields