MIDlet and Servlet : Servlet Invoke « J2ME « Java Tutorial

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3. Servlet Invoke

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import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import javax.microedition.lcdui.Choice;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.List;
import javax.microedition.lcdui.TextBox;
import javax.microedition.lcdui.TextField;
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;

public class SecondMidletServlet extends MIDlet implements CommandListener {
  Display display = null;
  List menu = null;
  TextBox input = null;
  String user = null;

  String url = "http://developer.java.sun.com/servlet/RequestServlet";
  static final Command backCommand = new Command("Back", Command.BACK, 0);
  static final Command submitCommand = new Command("Submit", Command.OK, 2);
  static final Command exitCommand = new Command("Exit", Command.STOP, 3);
  String currentMenu = null;

  public SecondMidletServlet() {
  }

  public void startApp() throws MIDletStateChangeException {
    display = Display.getDisplay(this);
    menu = new List("Invoke Servlet", Choice.IMPLICIT);
    menu.append("Add a user", null);
    menu.addCommand(exitCommand);
    menu.setCommandListener(this);
    mainMenu();
  }

  public void pauseApp() {
  }

  public void destroyApp(boolean unconditional) {
    notifyDestroyed();
  }

  void mainMenu() {
    display.setCurrent(menu);
  }

  public void addName() {
    input = new TextBox("Enter first name:", "", 5, TextField.ANY);
    input.addCommand(submitCommand);
    input.addCommand(backCommand);
    input.setCommandListener(this);
    input.setString("");
    display.setCurrent(input);
  }

  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");

      os = c.openOutputStream();
      String str = "name=" + user;
      byte postmsg[] = str.getBytes();
      System.out.println("Length: " + str.getBytes());
      for (int i = 0; i < postmsg.length; i++) {
        os.write(postmsg[i]);
      }
      // or you can easily do:
      // os.write(("name="+user).getBytes());
      os.flush();

      is = c.openDataInputStream();
      int ch;
      while ((ch = is.read()) != -1) {
        b.append((char) ch);
        System.out.print((char) ch);
      }
      t = new TextBox("Second Servlet", b.toString(), 1024, 0);
      t.addCommand(backCommand);
      t.setCommandListener(this);
    } finally {
      if (is != null) {
        is.close();
      }
      if (os != null) {
        os.close();
      }
      if (c != null) {
        c.close();
      }
    }
    display.setCurrent(t);
  }

  public void commandAction(Command c, Displayable d) {
    String label = c.getLabel();
    if (label.equals("Exit")) {
      destroyApp(true);
    } else if (label.equals("Back")) {
      mainMenu();
    } else if (label.equals("Submit")) {
      user = input.getString();
      try {
        invokeServlet(url);
      } catch (IOException e) {
      }
    } else {
      addName();
    }
  }
}