Socket MIDlet
/*
J2ME in a Nutshell
By Kim Topley
ISBN: 0-596-00253-X
*/
import java.io.InputStream;
import java.io.IOException;
import java.io.OutputStream;
import javax.microedition.io.Connector;
import javax.microedition.io.StreamConnection;
import javax.microedition.lcdui.Alert;
import javax.microedition.lcdui.AlertType;
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.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
public class SocketMIDlet extends MIDlet
implements CommandListener, Runnable {
private Display display;
private Form addressForm;
private Form connectForm;
private Form displayForm;
private TextField serverName;
private TextField serverPort;
private StringItem messageLabel;
private StringItem errorLabel;
private Command okCommand;
private Command exitCommand;
private Command backCommand;
protected void startApp() throws MIDletStateChangeException {
if (display == null) {
initialize();
display.setCurrent(addressForm);
}
}
protected void pauseApp() {
}
protected void destroyApp(boolean unconditional)
throws MIDletStateChangeException {
}
public void commandAction(Command cmd, Displayable d) {
if (cmd == okCommand) {
Thread t = new Thread(this);
t.start();
display.setCurrent(connectForm);
} else if (cmd == backCommand) {
display.setCurrent(addressForm);
} else if (cmd == exitCommand) {
try {
destroyApp(true);
} catch (MIDletStateChangeException ex) {
}
notifyDestroyed();
}
}
public void run() {
InputStream is = null;
OutputStream os = null;
StreamConnection socket = null;
try {
String server = serverName.getString();
String port = serverPort.getString();
String name = "socket://" + server + ":" + port;
socket = (StreamConnection)Connector.open(name, Connector.READ_WRITE);
} catch (Exception ex) {
Alert alert = new Alert("Invalid Address",
"The supplied address is invalid\n" +
"Please correct it and try again.", null,
AlertType.ERROR);
alert.setTimeout(Alert.FOREVER);
display.setCurrent(alert, addressForm);
return;
}
try {
// Send a message to the server
String request = "GET / HTTP/1.0\n\n";
os = socket.openOutputStream();
os.write(request.getBytes());
os.close();
// Read the server's reply, up to a maximum
// of 128 bytes.
is = socket.openInputStream();
final int MAX_LENGTH = 128;
byte[] buf = new byte[MAX_LENGTH];
int total = 0;
while (total < MAX_LENGTH) {
int count = is.read(buf, total, MAX_LENGTH - total);
if (count < 0) {
break;
}
total += count;
}
is.close();
String reply = new String(buf, 0, total);
messageLabel.setText(reply);
socket.close();
display.setCurrent(displayForm);
} catch (IOException ex) {
Alert alert = new Alert("I/O Error",
"An error occurred while communicating with the server.",
null, AlertType.ERROR);
alert.setTimeout(Alert.FOREVER);
display.setCurrent(alert, addressForm);
return;
} finally {
// Close open streams and the socket
try {
if (is != null) {
is.close();
is = null;
}
} catch (IOException ex1) {
}
try {
if (os != null) {
os.close();
os = null;
}
} catch (IOException ex1) {
}
try {
if (socket != null) {
socket.close();
socket = null;
}
} catch (IOException ex1) {
}
}
}
private void initialize() {
display = Display.getDisplay(this);
// Commands
exitCommand = new Command("Exit", Command.EXIT, 0);
okCommand = new Command("OK", Command.OK, 0);
backCommand = new Command("Back", Command.BACK, 0);
// The address form
addressForm = new Form("Socket Client");
serverName = new TextField("Server name:", "", 256, TextField.ANY);
serverPort = new TextField("Server port:", "", 8, TextField.NUMERIC);
addressForm.append(serverName);
addressForm.append(serverPort);
addressForm.addCommand(okCommand);
addressForm.addCommand(exitCommand);
addressForm.setCommandListener(this);
// The connect form
connectForm = new Form("Connecting");
messageLabel = new StringItem(null, "Connecting...\nPlease wait.");
connectForm.append(messageLabel);
connectForm.addCommand(backCommand);
connectForm.setCommandListener(this);
// The display form
displayForm = new Form("Server Reply");
messageLabel = new StringItem(null, null);
displayForm.append(messageLabel);
displayForm.addCommand(backCommand);
displayForm.setCommandListener(this);
}
}
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