www.pudn.com > chap8.rar > MailboxServlet.java

package chap8; 
 
import com.oreilly.javaxslt.util.StylesheetCache; 
import java.io.*; 
import java.net.*; 
import java.util.*; 
import javax.servlet.*; 
import javax.servlet.http.*; 
import javax.xml.parsers.*; 
import javax.xml.transform.*; 
import javax.xml.transform.stream.*; 
import org.w3c.dom.*; 
 
/** 
 * Demonstrates how to perform session tracking without cookies. 
 */ 
public class MailboxServlet extends HttpServlet { 
    private String xsltFileName; 
 
    /** 
     * Locate the XSLT stylesheet. 
     */ 
    public void init() throws UnavailableException { 
        this.xsltFileName = getServletContext().getRealPath( 
                "/WEB-INF/xslt/mailbox.xslt"); 
        if (!new File(this.xsltFileName).exists()) { 
            throw new UnavailableException("XSLT stylesheet not found: " 
                    + this.xsltFileName, 30); 
        } 
    } 
 
    /** 
     * Display the mailbox. 
     */ 
    public void doGet(HttpServletRequest req, HttpServletResponse res) 
            throws ServletException, IOException { 
        try { 
            // retrieve current settings from the session 
            HttpSession session = req.getSession(true); 
            Mailbox mbox = (Mailbox) session.getAttribute("mailbox"); 
            String curFolderName = 
                    (String) session.getAttribute("curFolderName"); 
            String curSortColumn = 
                    (String) session.getAttribute("curSortColumn"); 
 
            // produce the DOM tree 
            Document doc = MailboxDOMProducer.createMailboxDocument( 
                    mbox, curFolderName); 
 
            // prepare the XSLT transformation 
            Transformer trans = StylesheetCache.newTransformer( 
                    this.xsltFileName); 
 
            // tell the XSLT what column to sort on 
            if (curSortColumn != null) { 
                trans.setParameter("global.curSortColumn", curSortColumn); 
            } 
 
            // allow cookieless session tracking 
            if (!req.isRequestedSessionIdFromCookie()) { 
                String sessionID = session.getId(); 
                trans.setParameter("global.sessionID",  
                        ";jsessionid=" + sessionID); 
            } 
 
            // send the web page back to the user 
            res.setContentType("text/html"); 
            trans.transform(new javax.xml.transform.dom.DOMSource(doc), 
                    new StreamResult(res.getWriter())); 
 
        } catch (ParserConfigurationException pce) { 
            throw new ServletException(pce); 
        } catch (TransformerConfigurationException tce) { 
            throw new ServletException(tce); 
        } catch (TransformerException te) { 
            throw new ServletException(te); 
        } 
    } 
 
 
    /** 
     * Allow users to POST changes to mailbox settings. 
     */ 
    public void doPost(HttpServletRequest req, HttpServletResponse res) 
            throws ServletException, IOException { 
 
        // locate the session for the current user 
        HttpSession session = req.getSession(true); 
 
        // if the client changed the current folder, store the new 
        // value in the session 
        String curFolderName = req.getParameter("changeCurrentFolder"); 
        if (curFolderName != null) { 
            session.setAttribute("curFolderName", curFolderName); 
        } 
 
        // if the client changed the sort column, store the new value 
        // in the session. The parameter naming convention 
        // is: "sortOn[column]". For example, "sortOnfrom" or "sortOnto". 
        Enumeration paramNames = req.getParameterNames(); 
        while (paramNames.hasMoreElements()) { 
            String curName = (String) paramNames.nextElement(); 
            if (curName.startsWith("sortOn")) { 
                session.setAttribute("curSortColumn", 
                        curName.substring("sortOn".length())); 
                break; 
            } 
        } 
 
        // see if the user submitted a new username 
        String username = req.getParameter("username"); 
        if (username != null) { 
            // store the new mailbox in the session 
            Mailbox mbox = MailboxFactory.getMailbox(username); 
            session.setAttribute("mailbox", mbox); 
        } 
 
        // utilize the doGet method to show the page 
        doGet(req, res); 
    } 
}