HttpConnection hangs in my T630. Please Help !

Question

Hi all,
I`ve noticed this problem in a few threads on this forum, but none of them seem to have a definitive answer. Maybe we can answer it once and for all here :-) Any help would be greatly appreciated.
I`m trying to load a web page from a midlet in my T630. As I don`t really want to pay for call charges during development, I`m using the "Device Explorer" and the "Connection proxy" to try and connect to the internet using my broadband connection. I'm using the SonyEricsson developer kit (version 1) and I'm using a bluetooth serial connection on COM5 for the connection proxy.
I've based my code on some sample code from Sun to load some info from a web page. This code was even published to get around the IO blocking problem that I seem to be getting still !
The problem is when I try and use the HttpConnection.getResponseCode() method. Using the advice of other internet resources, I`ve put this code in its own thread. When I call HttpConnection.getResponseCode(), my T630 then pops ups with a menu, offering me these 3 options:
Allow Web access
Ask per access
Deny Web access
When this happens, it`s as if the thread running the getResponseCode() method blocks, and the T630 OS takes over. When I select an item from that menu, control does not pass back to the thread running getResponseCode(), but goes to the main midlet thread. Once I`m back in the main midlet thread, I don't know how to wake up the url loading thread. Does anyone have any ideas.
My debugging statements produce the following before the app hangs:
url=http://java.sun.com
conn=com.sun.midp.io.j2me.http.Protocol@e4857a1d
here
Connecting to http://java.sun.comHere is the source code:
package com.pg.midp.http;
import java.io.IOException;
import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.StringItem;
import javax.microedition.lcdui.TextBox;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
// Simple class that connects to a given URL and
// prints out the response code and any headers
// that are sent back. Shows how to use background
// threads to make HTTP connections while keeping the
// user interface alive.
public class HttpLogger extends MIDlet
     private Display display;
     private Command exitCommand = new Command([quot][/quot]Exit[quot][/quot], Command.EXIT, 1);
     private Command okCommand = new Command([quot][/quot]OK[quot][/quot], Command.OK, 1);
     private Command cancelCommand = new Command([quot][/quot]Cancel[quot][/quot], Command.CANCEL, 1);
     private URLEntry mainForm;
     // Standard MIDlet stuff....
     public HttpLogger()
     protected void debug(String s)
          System.out.println(s);
     protected void destroyApp(boolean unconditional) throws MIDletStateChangeException
          exitMIDlet();
     protected void pauseApp()
     protected void startApp() throws MIDletStateChangeException
          if (display == null)
               initMIDlet();
     private void initMIDlet()
          display = Display.getDisplay(this);
          mainForm = new URLEntry();
          display.setCurrent(mainForm);
     public void exitMIDlet()
          notifyDestroyed();
     // Utility routine to display exceptions.
     void displayError(Throwable e, Displayable next)
          Alert a = new Alert([quot][/quot]Exception[quot][/quot]);
          a.setString(e.toString());
          a.setTimeout(Alert.FOREVER);
          display.setCurrent(a, next);
     // Simple entry form for entering the URL to
     // connect to.
     class URLEntry extends TextBox implements CommandListener
          URLEntry()
               super([quot][/quot]Enter URL:[quot][/quot], [quot][/quot]java.sun.com[quot][/quot], 100, 0);
               addCommand(exitCommand);
               addCommand(okCommand);
               setCommandListener(this);
          public void commandAction(Command c, Displayable d)
               if (c == exitCommand)
                    exitMIDlet();
               else if (c == okCommand)
                    try
                         String url = [quot][/quot]http://[quot][/quot] + getString();
                         debug([quot][/quot]url=[quot][/quot] + url);
                         HttpConnection conn = (HttpConnection) Connector.open(url);
                         debug([quot][/quot]conn=[quot][/quot] + conn);
                         Logger logger = new Logger(this, conn);
                         debug([quot][/quot]here[quot][/quot]);
                         display.setCurrent(logger);
                    catch (IOException e)
                         displayError(e, this);
     //      Simple form that contains a single string item.
     //      The string item is updated with status messages.
     //      When constructed, it starts a background thread
     //      that makes the actual HTTP connection. Displays
     //      a Cancel command to abort the current connection.
     class Logger extends Form implements Runnable, CommandListener
          private Displayable next;
          private HttpConnection conn;
          private StringItem text = new StringItem(null, [quot][/quot][quot][/quot]);
          boolean done = false;
          Thread t;
          Logger(Displayable next, HttpConnection conn)
               super([quot][/quot]HTTP Log[quot][/quot]);
               this.next = next;
               this.conn = conn;
               addCommand(cancelCommand);
               setCommandListener(this);
               append(text);
               t = new Thread(this);
               t.start();
          // Handle the commands. First thing to do
          // is switch the display, in case closing/
          // the connection takes a while...
          public void commandAction(Command c, Displayable d)
               display.setCurrent(next);
               try
                    conn.close();
               catch (IOException e)
                    displayError(e, next);
          // Do the connection and processing on
          // a separate thread...
          public void run()
               try
                    update([quot][/quot]Connecting to [quot][/quot] + conn.getURL());
                    try
                         int rc = conn.getResponseCode();
                         update([quot][/quot]Response code: [quot][/quot] + rc);
                         update([quot][/quot]Response message: [quot][/quot] + conn.getResponseMessage());
                         String key;
                         for (int i = 0; (key = conn.getHeaderFieldKey(i)) != null; ++i)
                              update(key + [quot][/quot]: [quot][/quot] + conn.getHeaderField(i));
                    catch (IOException e)
                         update([quot][/quot]Caught exception: [quot][/quot] + e.toString());
               catch (Exception e)
                    debug(e.getMessage());
                    e.printStackTrace();
               finally
               done = true;
               removeCommand(cancelCommand);
               addCommand(okCommand);
          // Update the string item with new information.
          // Only do it if we're actually visible.
          void update(String line)
               debug(line);
               if (display.getCurrent() != this)
                    return;
               String old = text.getText();
               StringBuffer buf = new StringBuffer();
               buf.append(old);
               if (old.length() [gt][/gt] 0)
                    buf.append('\n');
               buf.append(line);
               text.setText(buf.toString());
}Thanks,
Paul.

Answer 1

Hi, Paulgrime:
These days I also have struggled with the problem.
I just saw a java example from SUN site, which does not use getResponseCode(). It seems a good work around.
I tried that way and works fine. Only thing is you have to figure out the response status by analysing the inputstream content, which is actually easy.
So I go this way now.
Huiyi