Captains Blog Supplemental: 10/01/2004

Thursday, October 14, 2004

Webservices on a J2ME mobile device

My latest experimenting with J2ME has led me to webservices. I've
managed to communicate with several online webservice providers
including http://www.xmethods.net/ and http://www.google.com/apis/ . I
managed to do this using the small footprint SOAP package kSOAP
http://ksoap.enhydra.org/ or http://www.ksoap.org/ .Here is a copy of
the template java midlet that I use to communicate to web-services
with:

Template.java

import java.io.IOException;

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.ImageItem;
import javax.microedition.lcdui.StringItem;
import javax.microedition.lcdui.TextBox;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

import org.ksoap.SoapObject;
import org.ksoap.transport.HttpTransport;

/**
* @author Yusuf
*
*/
public class Template extends MIDlet implements CommandListener {
private Display display;

private String url = "";

private String nameSpace = "";

private String name = "";

private String key = "";

private Command sendCommand;

private Command exitCommand;

private Command backCommand;

private StringItem stringItem;

private Form form1;

private TextField textField1, textField2;

private String choice;

private ImageItem background;

public Template() {
display = Display.getDisplay(this);
stringItem = new StringItem("", "");
textField1 = new TextField("Input 1:", choice, 30,
TextField.ANY);
textField2 = new TextField("Input 2:", choice, 30,
TextField.ANY);
exitCommand = new Command("Exit", Command.EXIT, 1);
sendCommand = new Command("Invoke", Command.SCREEN, 1);
backCommand = new Command("Back", Command.BACK, 1);
background = new ImageItem("", null,
ImageItem.LAYOUT_CENTER, "no pic");

// TODO Auto-generated constructor stub
}

/*
* (non-Javadoc)
*
* @see javax.microedition.midlet.MIDlet#startApp()
*/
protected void startApp() throws MIDletStateChangeException {
form1 = new Form("Webservices");
try {
//background.setImage(Image.createImage("/google.png"));
url = getAppProperty("URL");
nameSpace = getAppProperty("NAMESPACE");
name = getAppProperty("NAME");
key = getAppProperty("KEY");
//form1.append(background);
form1.append(textField1);
form1.append(textField2);
form1.append(stringItem);
form1.addCommand(sendCommand);
form1.addCommand(exitCommand);
form1.setCommandListener((CommandListener)
this);
display.setCurrent(form1);

// TODO Auto-generated method stub

} catch (Exception e) {
// TODO Auto-generated catch block
System.out.println(e);
e.printStackTrace();
}

}

/*
* (non-Javadoc)
*
* @see javax.microedition.midlet.MIDlet#pauseApp()
*/
protected void pauseApp() {
// TODO Auto-generated method stub

}

/*
* (non-Javadoc)
*
* @see javax.microedition.midlet.MIDlet#destroyApp(boolean)
*/
protected void destroyApp(boolean arg0) throws
MIDletStateChangeException {
// TODO Auto-generated method stub

}

public void doInvoke(String in1, String in2) throws Exception {
StringBuffer stringBuffer = new StringBuffer();
TextBox textBox = null;
SoapObject client = new SoapObject(nameSpace, name);
//client.addProperty("LKEY", "0");
//client.addProperty("FromName", "Yusuf");
//client.addProperty("ToUserID",
"yusufk18@hotmail.com");
//client.addProperty("Message", "Watse");
//client.addProperty("CityName", "Pretoria");
//client.addProperty("CountryName", "South Africa");
//client.addProperty("myString", "hello");
client.addProperty("FromCurrency", in1);
client.addProperty("ToCurrency", in2);
HttpTransport ht = new HttpTransport(url, nameSpace);
try {
stringBuffer.append(ht.call(client));

} catch (IOException e) {
// TODO Auto-generated catch block
System.out.println(e);
e.printStackTrace();
System.out.println(client.getNamespace());

}
stringItem.setText(stringBuffer.toString());
System.out.println(stringBuffer);
}

/*
* (non-Javadoc)
*
* @see
javax.microedition.lcdui.CommandListener#commandAction(javax.microedition.lcdui.Command,
* javax.microedition.lcdui.Displayable)
*/
public void commandAction(Command command, Displayable arg1) {
if (command == sendCommand) {

Thread t = new Thread() {
String input1 = textField1.getString();

String input2 = textField2.getString();

public void run() {
try {
doInvoke(input1,
input2);
} catch (Exception e) {
e.printStackTrace();
}
}
};
t.start();

} else if (command == backCommand) {

display.setCurrent(form1);

}

else if (command == exitCommand) {
try {
destroyApp(false);
notifyDestroyed();
} catch (Exception e) {
e.printStackTrace();
}

}

}

}

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