Thank you Jimboo:
Below is the servlet file that mainly responsible for the form:
/*
package iat;
import iat.db.Metadata;
import java.io.IOException;
import java.util.ArrayList;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.w3c.dom.Element;
import sfu.util.JUtil;
import sfu.util.XmlApi;
/**
* <p>Title: MetadataServlet </p>
*
* <p>Description: This servlet provides Metadata APIs.</p>
*
* @author Ty Mey Eap
* @version 1.0
*/
public class MetadataServlet extends HttpServlet {
static Metadata metadata = null;
/**
* we have to implement HttpServlet interface, but we do not have to do anything
*/
public void init(ServletConfig config) throws ServletException {
}
/**
* creates and returns the instance of Metadata
*/
public static Metadata geMetadataClass(){
if (metadata == null){
metadata = new Metadata();
}
return metadata;
}
/**
* redirects to processAction
*/
public void doGet(HttpServletRequest request, HttpServletResponse response) throws
IOException, ServletException {
processAction(request, response);
}
/**
* redirects to processAction
*/
public void doPost(HttpServletRequest request, HttpServletResponse response) throws
IOException, ServletException {
processAction(request, response);
}
/**
* processAction processes all incoming requests.
*/
public static void processAction(HttpServletRequest request, HttpServletResponse response) throws
IOException, ServletException {
response.setContentType("text/xml");
Metadata md = geMetadataClass();
Element output = null;
String msg = null;
boolean done = false;
String username = (String)request.getSession(true).getAttribute("username");
try{
String action = JSPUtil.getParam(request, "action", "");
System.out.println("Action Parameter:"+action);
if (action.equals("hit")){
String midStr = request.getParameter("mid");
String url = request.getParameter("url");
int mid = JUtil.parseInt(midStr, 0);
if (mid > 0 && !JUtil.isNull(url)){
takeHit(midStr, request);
response.sendRedirect(url);
done = true;
}else{
throw new Exception("Bad url!");
}
}else if (action.equals("add")){
output = md.getEmptyElement();
output.setAttribute("msgType", "saveNew");
}else if (action.equals("edit")){
output = md.getMetadata(JSPUtil.getInt(request, "mid", -1));
output.setAttribute("msgType", "saveUpdate");
}else if (action.equals("saveUpdate")){
int mid = JSPUtil.getInt(request, "mid", -1);
try{
output = md.update(mid, JSPUtil.getParam(request,"lang", null),
JSPUtil.getParam(request,"media_type", null),
JSPUtil.getParam(request,"url",null),JSPUtil.getParam(request,"authors",""),
JSPUtil.getParam(request,"publisher",""), JSPUtil.getParam(request,"format", null),
JSPUtil.getParam(request,"title", null),JSPUtil.getParam(request,"description",""));
output.setAttribute("msgType", "view");
}catch(Exception ex){
output = createMd(md, request, mid);
output.setAttribute("msgType", "saveUpdate");
XmlApi.createChildElement(output, ConfigServlet.NS, "error", "U R WRONG:"+ex.getMessage());
}
}else if (action.equals("saveNew")){
try{
output = md.add(JSPUtil.getParam(request,"lang", null),
JSPUtil.getParam(request,"media_type", null),
JSPUtil.getParam(request,"url",null),JSPUtil.getParam(request,"authors",""),
JSPUtil.getParam(request,"publisher",""), JSPUtil.getParam(request,"format", null),
JSPUtil.getParam(request,"title", null),JSPUtil.getParam(request,"description",""));
output.setAttribute("msgType", "view");
}catch(Exception ex){
output = createMd(md, request, -1);
XmlApi.createChildElement(output, ConfigServlet.NS, "error", "ADD WRONG:"+ex.getMessage());
output.setAttribute("msgType", "saveNew");
}
}else if (action.equals("search")){
output = md.search(JSPUtil.getParam(request,"keywords", null));
output.setAttribute("msgType", "search");
}else if (action.equals("delete")){
output = md.getMdElement();
output.setAttribute("msgType", "delete");
}else{
output = md.getMdElement();
output.setAttribute("msgType", "home");
}
}catch(Exception e){
e.printStackTrace();
msg = "Exception message:"+e.getMessage();
}
try{
if (!done){
if (output == null){
output = metadata.getMdElement();
}
if (msg != null){
XmlApi.createChildElement(output, ConfigServlet.NS, "error",msg);
}
response.getWriter().println(outputResult(output, username));
}
}catch(Exception ex){
throw new ServletException(ex.getMessage());
}
}
private static Element createMd(Metadata md, HttpServletRequest request,
int mid)throws Exception{
Element output = md.getMdElement();
String id = (mid > 0)?String.valueOf(mid):"";
md.addMetadata(output, id, JSPUtil.getParam(request,"lang", ""),
JSPUtil.getParam(request,"media_type", ""),
JSPUtil.getParam(request,"url",""),JSPUtil.getParam(request,"authors",""),
JSPUtil.getParam(request,"publisher",""), JSPUtil.getParam(request,"format", ""),
JSPUtil.getParam(request,"title", ""),JSPUtil.getParam(request,"description",""));
return output;
}
private static void takeHit(String mid, HttpServletRequest request)throws Exception{
HttpSession session = request.getSession(true);
ArrayList<String> accessedMedia = (ArrayList<String>)session.getAttribute("accessedMedia");
if (accessedMedia == null){
accessedMedia = new ArrayList<String>();
session.setAttribute("accessedMedia", accessedMedia);
}else{
if (accessedMedia.size() > 4){
accessedMedia.remove(0);
}
}
accessedMedia.add(mid);
metadata.updateHit(mid);
}
private static String outputResult(Element root, String userId)throws Exception{
return JSPUtil.outputWithXsltHeader(userId, "metadata.xsl", root);
}
/**
* we have to implement HttpServlet interface, but we do not have to do anything
*/
public void destroy() {
}
}