Typically sitemap.xml is a static file that is hand generated.  But on large sites it makes more sense to generate this dynamically.  One way to do this is to generate it on demand using a servlet.  Here is my simple solution.  I did not include the implementation for outputPages() since that will be specific to each application server’s DB hierarchy or web server’s file structure.

public class SiteMap extends HttpServlet {

  protected static final String MIME_TYPE_XML = "application/xml";

  // XML tags
  protected static final String SITE_MAP_XML_INFO = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>";
  protected static final String SITE_MAP_BEGIN =
      "<urlset\n\txmlns=\"http://www.sitemaps.org/schemas/sitemap/0.9\"\n\txmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n\txsi:schemaLocation=\"http://www.sitemaps.org/schemas/sitemap/0.9\n\t\thttp://www.sitemaps.org/schemas/sitemap/0.9/sitemap.xsd\">";
  protected static final String SITE_MAP_END = "</urlset>";

  protected static final String LOC_BEGIN = " <loc>";
  protected static final String LOC_END = "</loc>";
  protected static final String PRIORITY_BEGIN = " <priority>";
  protected static final String PRIORITY_END = "</priority>";
  protected static final String URL_BEGIN = "<url>";
  protected static final String URL_END = "</url>";

  @Override
  public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException {

    // set content type to be XML
    response.setContentType(MIME_TYPE_XML);

    // get writer
    PrintWriter out = response.getWriter();

    // output header
    out.println(SITE_MAP_XML_INFO);
    out.println(SITE_MAP_BEGIN);

    // output pages
    outputPages(request, out);

    // output end
    out.println(SITE_MAP_END);
    out.close();
  }

  protected void outputPage(String uri, String priority, PrintWriter out, String urlStart) {
    out.println(URL_BEGIN);
    out.println(LOC_BEGIN + urlStart + uri + LOC_END);
    out.println(PRIORITY_BEGIN + priority + PRIORITY_END);
    out.println(URL_END);
  }
}

Then you configure web.xml to use the SiteMap servlet.

<servlet>
    <servlet-name>sitemap</servlet-name>
    <servlet-class>com.upromise.olm.app.servlet.SiteMap</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>sitemap</servlet-name>
    <url-pattern>/sitemap.xml</url-pattern>
</servlet-mapping>

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