Servlets use HTTP request-reqponse protocol to send/recieve data from server. HTTPConnection interface of javax.microedition.io package is used.

Example below send any text to servlet and get response code from servlet.

 import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import javax.microedition.io.*;
import java.io.*;
import java.util.Vector;

public class MidletServlet extends MIDlet implements CommandListener {
    Display display = null;
    Form form = null;
    TextField tb = null;
    String str = null;
    String url = "http://localhost:8080/servlets-examples/servlet/getText";
    Command backCommand = new Command("Back", Command.BACK, 0);
    Command submitCommand = new Command("Submit", Command.OK, 2);
    Command exitCommand = new Command("Exit", Command.STOP, 3);
    private Test test;
    
    public MidletServlet() {}
    
    public void startApp() throws MIDletStateChangeException {
        display = Display.getDisplay(this);
        form = new Form("Request Servlet");
        tb = new TextField("Please input text: ","",30,TextField.ANY );
        form.append(tb);
        form.addCommand(submitCommand);
        form.addCommand(exitCommand);
        form.setCommandListener(this);
        display.setCurrent(form);
    }
    
    public void pauseApp() {}
    
    public void destroyApp(boolean unconditional) {}
    
    public void commandAction(Command c, Displayable d) {
        if (c == exitCommand) {
            destroyApp(true);
            notifyDestroyed();
        } else if (c == backCommand) {
            display.setCurrent(form);
        } else if (c == submitCommand) {
            str = tb.getString();
            test  = new Test(this);
            test.start();
            test.getServlet(str);
        }
    }
    
    
    class Test implements Runnable {
        MidletServlet midlet;
        private Display display;
        String text;
        
        public Test(MidletServlet midlet) {
            this.midlet = midlet;
            display = Display.getDisplay(midlet);
        }
        
        public void start() {
            Thread t = new Thread(this);
            t.start();
        }
        
        public void run() {
            StringBuffer sb = new StringBuffer();
            try {
                HttpConnection c = (HttpConnection) Connector.open(url);
                c.setRequestProperty(
                  "User-Agent","Profile/MIDP-1.0, Configuration/CLDC-1.0");
                
                c.setRequestProperty("Content-Language","en-US");
                c.setRequestMethod(HttpConnection.POST);
                
                DataOutputStream os = 
                        (DataOutputStream)c.openDataOutputStream();
                
                os.writeUTF(text.trim());
                os.flush();
                os.close();
                
                // Get the response from the servlet page.
                DataInputStream is =(DataInputStream)c.openDataInputStream();
                //is = c.openInputStream();
                int ch;
                sb = new StringBuffer();
                while ((ch = is.read()) != -1) {
                    sb.append((char)ch);
                }
                showAlert(sb.toString());
                is.close();
                c.close();
            } catch (Exception e) {
                showAlert(e.getMessage());
            }
        }
                /* This method takes input from user like text and pass
                to servlet */
        public void getServlet(String text) {
            this.text = text;
        }
        
        /* Display Error On screen*/
        private void showAlert(String err) {
            Alert a = new Alert("");
            a.setString(err);
            a.setTimeout(Alert.FOREVER);
            display.setCurrent(a);
        }
    };
}

import java.io.*;
import java.text.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class getText extends HttpServlet {
    
    public void init() {
    }
    
    public void doPost(HttpServletRequest request, 
            HttpServletResponse response) throws ServletException, 
            IOException {
        
        DataInputStream in = 
                new DataInputStream((InputStream)request.getInputStream());
        
        String text = in.readUTF();
        String message;
        try {
            message = "100 ok";
        } catch (Throwable t) {
            message = "200 " + t.toString();
        }
        response.setContentType("text/plain");
        response.setContentLength(message.length());
        PrintWriter out = response.getWriter();
        out.println(message);
        in.close();
        out.close();
        out.flush();
    }
    
    public void doGet(HttpServletRequest request,
            HttpServletResponse response) throws ServletException, 
            IOException {
        
        doPost(request,response);
    }
}

 
 Related Tips