Midlet gets null values from servlet

Question

hey,
based on one of the source code examples on the java.sun.com website i made a midlet/servlet application. the midlet is sending a product id to the servlet, the servlet queries the database and shows the productinformation, the midlet reads the servlet output and displays it on his midlet form
when i invoke the servlet in my browser: http://localhost:8080/Magazijn/query?product=1 then everything works fine (i see: Product Name : Deur). when the midlet is invoking the servlet i see Product Name : null
after hours of searching the only thing i could come up with is that the servlet isn't passing the string retrieved from the resultset to the midlet
the strange thing is that when i papss a normal string, for instance:
String test = "test";
out.println(test);
that he shows this correct both in my browser and midlet
when i do this:
prodName = resutl.getString("name");
out.println(prodName);
i see "Deur" in my browser, but i see "null" in my midlet
anyone can help me?
here's the servlet source:
import java.io.*;
import java.sql.*;
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.Date;
public class Magazijn extends HttpServlet {
public void doGet(HttpServletRequest request,
          HttpServletResponse response)
                    throws IOException, ServletException {
          doPost(request,response);
public void doPost(HttpServletRequest request,
          HttpServletResponse response)
                    throws IOException, ServletException {
     String url="jdbc:mysql://localhost/test?user=root&password=root";
     Connection con = null;
     Statement stmt;
     ResultSet rs;
     String query;
     int prodId;
     String prodNaam;
     String prodPlaats;
     String prodAantal;
     response.setContentType("text/plain");
     PrintWriter out = response.getWriter();
     BufferedReader br = request.getReader();
     String buf = br.readLine();
     try {
               //laden van de mysql driver
               Class.forName("com.mysql.jdbc.Driver");
               //maken van connectie met database
               con = DriverManager.getConnection (url, "root", "root");     
               //aanmaken van statement object
               stmt = con.createStatement();
               //nakijken welke naam we zoeken van product
               String prod = request.getParameter("product");
               //uitvoeren van query en die opvangen in een resultset
               query = "SELECT * from onderdelen where id="+prod;
               ResultSet result = stmt.executeQuery(query);
               result.next();
               prodId = result.getInt("id");
               prodNaam = result.getString("naam");
               prodPlaats = result.getString("plaats");
               prodAantal = result.getString("aantal");
          out.println(new Date());
          out.println("");
               out.println("Product ID: "+prodId);
               out.println("Productnaam: "+prodNaam);
               out.println("Plaats: "+prodPlaats);
               out.println("Aantal: "+prodAantal);
          catch(ClassNotFoundException e) {
               out.println("Could not load database driver: " + e.getMessage());
          catch(SQLException e) {
               out.println("SQLException caught: " + e.getMessage());
          finally {
               //sluiten database connectie
               try {
                    if (con != null) con.close();
               catch (SQLException e) {}
here's the midlet source:
import javax.microedition.rms.*;
import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import javax.microedition.io.*;
import java.io.*;
import java.util.Vector;
public class MagazijnMidlet extends MIDlet implements CommandListener {
Display display = null;
List menu = null;
TextBox input = null;
String prodid = null;
String url = "http://localhost:8080/Magazijn/query";
static final Command backCommand = new Command("Terug", Command.BACK, 0);
static final Command submitCommand = new Command("Verstuur", Command.OK, 2);
static final Command exitCommand = new Command("Afsluiten", Command.STOP, 3);
String currentMenu = null;
public MagazijnMidlet() { }
public void startApp() throws MIDletStateChangeException {
display = Display.getDisplay(this);
menu = new List("Maak uw keuze", Choice.IMPLICIT);
menu.append("Opvragen product gegevens", null);
menu.addCommand(exitCommand);
menu.setCommandListener(this);
mainMenu();
public void pauseApp() { }
public void destroyApp(boolean unconditional) {
notifyDestroyed();
void mainMenu() {
display.setCurrent(menu);
//Vraag om productnummer op te geven
public void askProdid() {
input = new TextBox("Geef Productnummer:","", 5, TextField.ANY);
input.addCommand(submitCommand);
input.addCommand(backCommand);
input.setCommandListener(this);
input.setString("");
display.setCurrent(input);
//Maken connectie midlet + verwerking
void invokeServlet(String url) throws IOException {
HttpConnection c = null;
InputStream is = null;
OutputStream os = null;
StringBuffer b = new StringBuffer();
TextBox t = null;
try {
c = (HttpConnection)Connector.open(url);
c.setRequestMethod(HttpConnection.POST);
c.setRequestProperty("IF-Modified-Since",
     "20 Jan 2001 16:19:14 GMT");
c.setRequestProperty("User-Agent",
     "Profile/MIDP-1.0 Configuration/CLDC-1.0");
c.setRequestProperty("Content-Language", "en-CA");
// send request to the servlet.
os = c.openOutputStream();
String str = "product="+prodid;
byte postmsg[] = str.getBytes();
System.out.println("Length: "+str.getBytes());
for(int i=0;i<postmsg.length;i++) {
os.write(postmsg);
// or you can easily do:
//os.write(("product="+prodid).getBytes());
os.flush();
// receive response and display it in a textbox.
is = c.openInputStream();
int ch;
while((ch = is.read()) != -1) {
b.append((char) ch);
System.out.print((char)ch);
Form formProdGeg = new Form ("Gegevens product");
StringItem infoItem = new StringItem("",b.toString());
formProdGeg.append (infoItem);
formProdGeg.addCommand (backCommand);
formProdGeg.setCommandListener (this);
display.setCurrent (formProdGeg);
} finally {
if(is!= null) {
is.close();
if(os != null) {
os.close();
if(c != null) {
c.close();
display.setCurrent(t);
// event handler
public void commandAction(Command c, Displayable d) {
String label = c.getLabel();
if(label.equals("Afsluiten")) {
destroyApp(true);
} else if (label.equals("Terug")) {
mainMenu();
} else if (label.equals("Verstuur")) {
prodid = input.getString();
try {
invokeServlet(url);
}catch(IOException e) {}
} else {
askProdid();
tia
lee

Answer 1

Hi,
first for some efficeincy, in your place your connection to the database in the init() method so you can have on instance of the connection.
in your midlet place the ui initialization in its constructor
ok, Why dont you try the query in the url
i.e http://localhost:8080/Magazijn/query=";
then as you input the product id without setting requests
c = (HttpConnection)Connector.open(url+productid);
i think it will work properly
tell me what happens with you