Java Tutorial/J2ME/Servlet Invoke

An example MIDlet to invoke a CGI script

/* License
 * 
 * Copyright 1994-2004 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  
 *  * Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *  * Redistribution in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *  
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *  
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility. 
 */
import java.io.IOException;
import java.io.InputStream;
import javax.microedition.io.Connector;
import javax.microedition.io.HttpConnection;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.TextBox;
import javax.microedition.midlet.MIDlet;
/**
 * An example MIDlet to invoke a CGI script.
 */
public class FirstMidletServlet extends MIDlet {
  private Display display;
  String url = "http://127.0.0.1/HelloServlet";
  public FirstMidletServlet() {
    display = Display.getDisplay(this);
  }
  /**
   * Initialization. Invoked when we activate the MIDlet.
   */
  public void startApp() {
    try {
      invokeServlet(url);
    } catch (IOException e) {
      System.out.println("IOException " + e);
      e.printStackTrace();
    }
  }
  /**
   * Pause, discontinue ....
   */
  public void pauseApp() {
  }
  /**
   * Destroy must cleanup everything.
   */
  public void destroyApp(boolean unconditional) {
  }
  /**
   * Prepare connection and streams then invoke servlet.
   */
  void invokeServlet(String url) throws IOException {
    HttpConnection c = null;
    InputStream is = null;
    StringBuffer b = new StringBuffer();
    TextBox t = null;
    try {
      c = (HttpConnection) Connector.open(url);
      c.setRequestMethod(HttpConnection.GET);
      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");
      is = c.openDataInputStream();
      int ch;
      while ((ch = is.read()) != -1) {
        b.append((char) ch);
        // System.out.println((char)ch);
      }
      t = new TextBox("First Servlet", b.toString(), 1024, 0);
    } finally {
      if (is != null) {
        is.close();
      }
      if (c != null) {
        c.close();
      }
    }
    display.setCurrent(t);
  }
}

MIDlet and Servlet

/* License
 * 
 * Copyright 1994-2004 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *  
 *  * Redistribution of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 * 
 *  * Redistribution in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 * 
 * Neither the name of Sun Microsystems, Inc. or the names of contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *  
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MICROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
 * REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL,
 * INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND REGARDLESS OF THE THEORY
 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
 * EVEN IF SUN HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.
 *  
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
 * nuclear facility. 
 */
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.rumand;
import javax.microedition.lcdui.rumandListener;
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.ru/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();
    }
  }
}