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Thread: Servlet/Applet

  1. #1
    Guest

    Servlet/Applet

    Hi,
    I want to invoke an servlet from an applet and send some data(int value)back to the applet.How can I do this?.I'm not able to get the result back to the applet.
    My code is as follows.....


    import java.awt.*;
    import java.io.*;
    import java.net.*;


    public class CountServletApplet extends java.applet.Applet
    {
    private TextField SessionField;
    private Button SessionCount;
    private Button GlobalCount;
    private Button FileCount;



    private URLConnection connect;
    private URL u1;

    String sum = "0";
    public CountServletApplet()
    {
    setLayout(new FlowLayout());
    add(new Label("Count"));
    SessionCount = new Button("Session Count");
    FileCount = new Button("File Count");
    GlobalCount = new Button("GlobalCount");
    SessionField = new TextField("1");
    add(SessionCount);
    add(GlobalCount);
    add(FileCount);
    add(SessionField);
    setVisible(true);
    setSize(600,600);
    }
    public boolean action(Event e, Object arg)
    {
    if(e.target == SessionCount)
    {
    try
    {
    System.out.println("Resetting Count..");
    u1 = new URL(getDocumentBase(),"/servlet/CountServlet?operation=increment");
    connect = u1.openConnection();
    connect.setDefaultUseCaches(false);
    connect.setUseCaches(false);
    connect.setDoInput(true);
    connect.setDoOutput(true);
    connect.connect();
    DataInputStream in = new DataInputStream(new BufferedInputStream(connect.getInputStream()));
    String response = in.readLine();
    System.out.println(response);
    SessionField.setText(response);
    in.close();
    }
    catch(Exception x)
    {
    System.out.println("System Exception " + x);
    }
    return true;
    }
    return false;
    }

    }


    //servlet part
    import java.io.*;
    import javax.servlet.*;
    import javax.servlet.http.*;

    public class CountServlet extends HttpServlet
    {
    int count;

    public void init(ServletConfig conf) throws ServletException
    {
    super.init(conf);
    count = 0;
    }

    public void service(HttpServletRequest req, HttpServletResponse res)
    {
    try
    {
    String str;
    str = req.getParameter("operation");

    if(str.equals("increment"))
    {
    res.setContentType("text/html");
    PrintWriter out = res.getWriter();
    HttpSession session = req.getSession(true);
    Integer count = (Integer)session.getValue("tracker.count");
    if(count == null)
    count = new Integer(1);
    else
    count = new Integer(count.intValue() + 1);
    session.putValue("tracker.count",count);
    ServletOutputStream out1 = res.getOutputStream();
    res.setContentType("text/html");
    out1.println(" " + count);
    out1.close();
    }

    else if(str.equals("reset"))
    {
    count = 0;
    ServletOutputStream out = res.getOutputStream();
    res.setContentType("text/html");
    out.println(" " + count);
    out.close();
    }
    }
    catch(Exception e)
    {
    System.out.println("Error" + e);
    }
    }
    }



  2. #2
    Join Date
    May 1999
    Location
    Pune, MH, India.
    Posts
    453

    Re: Servlet/Applet

    Have checked if the servlet is running fine? I can't check it here as, I can't run servlets on my machine.

    Just in case, one way is to give the URL in ur browser 'http://yourhost/servlet/CountServlet?operation=increment'.
    If u get some error page, it means there is some problem on server side.
    If browser shows a blank page, view the source and see if u have got the count.
    If u have got the count also, then server-side is correct.

    In the applet try this code...

    URL url = new URL(getDocumentBase(),"/servlet/CountServlet?operation=increment");
    DataInputStream in = new DataInputStream(new BufferedInputStream(url.openStream()));

    // read the contents in the stream




    - UnicMan
    http://members.tripod.com/unicman

  3. #3
    Join Date
    Aug 1999
    Location
    Bangalore,India
    Posts
    2

    Re: Servlet/Applet

    Visit http://servlets.com and download COS.JAR package.
    It contains lot of classes for sending messages/objects to and fro applet/servlet.

    Regards,
    saM


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