下面是在 blog-mover 中实现的一个类，直接贴源码吧（代码中可能存在的Bug，对您造成的误解，我不负责哟，要查看全部源码请访问 http://code.google.com/p/blog-mover），关于 Rome 的更多信息参见 http://rome.dev.java.net. Rome 可是出自 Sun 之手。有着这样的 package name：com.sun.syndication。

/**
 * Created on 2006-9-10 上午02:32:57
 */
package com.redv.blogmover.feed;

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.regex.Pattern;

import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.SystemUtils;

import com.redv.blogmover.Attachment;
import com.redv.blogmover.BlogMoverException;
import com.redv.blogmover.Comment;
import com.redv.blogmover.WebLog;
import com.redv.blogmover.impl.AbstractBlogWriter;
import com.redv.blogmover.web.DownloadFileServlet;
import com.sun.syndication.feed.synd.SyndContent;
import com.sun.syndication.feed.synd.SyndContentImpl;
import com.sun.syndication.feed.synd.SyndEntry;
import com.sun.syndication.feed.synd.SyndEntryImpl;
import com.sun.syndication.feed.synd.SyndFeed;
import com.sun.syndication.feed.synd.SyndFeedImpl;
import com.sun.syndication.io.FeedException;
import com.sun.syndication.io.SyndFeedOutput;

/**
 * 使用 <a href="https://rome.dev.java.net/">Rome</a> 将日志导出成下列格式：RSS 0.90, RSS
 * 0.91 Netscape, RSS 0.91 Userland, RSS 0.92, RSS 0.93, RSS 0.94, RSS 1.0, RSS
 * 2.0, Atom 0.3, and Atom 1.0。
 *
 * @author <a href="mailto:zhoushuqun@gmail.com">Shutra Zhou</a>
 *
 */
public class RomeWriter extends AbstractBlogWriter {
    private final Pattern pattern = DownloadFileServlet.TEMP_FILE_NAME_PATTERN;

    private final String encoding = "UTF-8";

    private SyndFeed feed;

    private List<SyndEntry> entries;

    private File outputFile;

    private String feedType;

    private String title;

    private String link;

    private String description;

    private String language;

    private String copyright;

    private String author;

    /**
     * @return the outputFile
     */
    public File getOutputFile() {
        return outputFile;
    }

    /**
     * @param outputFile
     *            the outputFile to set
     */
    public void setOutputFile(File outputFile) {
        this.outputFile = outputFile;
    }

    /**
     *
     * @param filePath
     *            the outputFile's name to set
     */
    public void setFilename(String filename) throws BlogMoverException {
        if (!pattern.matcher(filename).matches()) {
            throw new BlogMoverException("Parameter filename is not matched "
                    + this.pattern.pattern() + ".");
        }

        File tmpdir = new File(SystemUtils.JAVA_IO_TMPDIR);
        this.outputFile = new File(tmpdir, filename);
    }

    /**
     * @param author
     *            the author to set
     */
    public void setAuthor(String author) {
        this.author = author;
    }

    /**
     * @param copyright
     *            the copyright to set
     */
    public void setCopyright(String copyright) {
        this.copyright = copyright;
    }

    /**
     * @param description
     *            the description to set
     */
    public void setDescription(String description) {
        this.description = description;
    }

    /**
     * @param feedType
     *            the feedType to set
     */
    public void setFeedType(String feedType) {
        this.feedType = feedType;
    }

    /**
     * @param language
     *            the language to set
     */
    public void setLanguage(String language) {
        this.language = StringUtils.replace(language, "_", "-");
    }

    /**
     * @param link
     *            the link to set
     */
    public void setLink(String link) {
        this.link = link;
    }

    /**
     * @param title
     *            the title to set
     */
    public void setTitle(String title) {
        this.title = title;
    }

    /*
     * (non-Javadoc)
     *
     * @see com.redv.blogmover.impl.AbstractBlogWriter#begin()
     */
    @Override
    protected void begin() throws BlogMoverException {
        this.feed = new SyndFeedImpl();
        this.feed.setEncoding(this.encoding);
        this.feed.setFeedType(this.feedType);
        this.feed.setTitle(this.title);
        this.feed.setLink(this.link);
        this.feed.setDescription(this.description);
        this.feed.setLanguage(this.language);
        this.feed.setCopyright(this.copyright);
        this.feed.setAuthor(this.author);
        this.entries = new ArrayList<SyndEntry>();
        this.feed.setEntries(this.entries);
    }

    /*
     * (non-Javadoc)
     *
     * @see com.redv.blogmover.impl.AbstractBlogWriter#end()
     */
    @Override
    protected void end() throws BlogMoverException {
        SyndFeedOutput output = new SyndFeedOutput();
        OutputStream outputStream = null;
        Writer writer = null;
        try {
            outputStream = new FileOutputStream(this.outputFile);
            writer = new OutputStreamWriter(outputStream, this.encoding);
            output.output(feed, writer);
        } catch (IOException e) {
            throw new BlogMoverException(e);
        } catch (FeedException e) {
            throw new BlogMoverException(e);
        } finally {
            if (writer != null) {
                try {
                    writer.close();
                } catch (IOException e) {
                    log.warn(e);
                }
            }
            if (outputStream != null) {
                try {
                    outputStream.close();
                } catch (IOException e) {
                    log.warn(e);
                }
            }
        }
    }

    /*
     * (non-Javadoc)
     *
     * @see com.redv.blogmover.impl.AbstractBlogWriter#writeAttachment(com.redv.blogmover.Attachment)
     */
    @Override
    protected String writeAttachment(Attachment att) {
        return null;
    }

    /*
     * (non-Javadoc)
     *
     * @see com.redv.blogmover.impl.AbstractBlogWriter#writeBlog(com.redv.blogmover.WebLog,
     *      java.util.Map)
     */
    @Override
    protected void writeBlog(WebLog webLog, Map<Attachment, String> attachments)
            throws BlogMoverException {
        // 注意：格式 RSS 0.90, RSS 0.91 Netscape, RSS 0.91 Userland 的日志数量只能在1～15之间。
        if ((this.feedType.equals("rss_0.9")
                || this.feedType.equals("rss_0.91N") || this.feedType
                .equals("rss_0.91U"))
                && this.entries.size() >= 15) {
            return;
        }
        SyndEntry entry = new SyndEntryImpl();
        entry.setAuthor(this.author);
        entry.setTitle(webLog.getTitle());
        entry.setLink(webLog.getUrl());
        entry.setPublishedDate(webLog.getPublishedDate());
        entry.setUri(webLog.getUrl());

        if (webLog.getExcerpt() != null) {
            SyndContent description = new SyndContentImpl();
            description.setType("text/html");
            description.setValue(webLog.getExcerpt());
            entry.setDescription(description);
        } else if (this.feedType.equals("rss_2.0")) {
            SyndContent description = new SyndContentImpl();
            description.setType("text/html");
            description.setValue("");
            entry.setDescription(description);
        } else {
            // Do nothing.
        }

        List<SyndContent> contents = new ArrayList<SyndContent>();
        SyndContentImpl sc = new SyndContentImpl();
        sc.setType("text/html");
        sc.setValue(webLog.getBody());
        contents.add(sc);
        entry.setContents(contents);

        this.entries.add(entry);
    }

    /*
     * (non-Javadoc)
     *
     * @see com.redv.blogmover.impl.AbstractBlogWriter#writeComment(com.redv.blogmover.Comment)
     */
    @Override
    protected void writeComment(Comment comment) throws BlogMoverException {

    }

    public static void main(String[] args) throws IOException, FeedException {
        SyndFeedImpl feed = new SyndFeedImpl();
        feed.setFeedType("rss_0.90");
        feed.setTitle("site title");
        feed.setLink("http://shutra.xpert.cn");
        feed.setDescription("site description");
        feed.setLanguage("zh-CN");
        feed.setCopyright("copyright");
        feed.setAuthor("author");

        List<SyndEntry> entries = new ArrayList<SyndEntry>();
        feed.setEntries(entries);
        for (int i = 0; i < 2; i++) {
            SyndEntry entry = new SyndEntryImpl();
            entry.setAuthor("author");
            entry.setTitle("title");
            entry.setLink("http://xpert.cn/" + i);

            List contents = new ArrayList();
            entry.setContents(contents);
            entries.add(entry);
        }

        SyndFeedOutput output = new SyndFeedOutput();
        List l = feed.getSupportedFeedTypes();
        for (Object s : l) {
            feed.setFeedType(s.toString());
            try {
                output.output(feed, new File("C:\\tmp\\t_" + s + ".xml"));
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
    }
}

by Shutra