Re: How to login to a site using cookie? (not applet)

On Jul 14, 2:24 am, Roedy Green <see_webs...@mindprod.com.invalid>
wrote:


Thanks Roedy.

What about Cookie? Firefox stores this cookie called "stn"
after I logged in, but if I delete this cookie and refresh,
I will be kicked back to the front login screen. So I think
it is the session id cookie. Don't I need to send back
a session id every time I POST?

Also, how does the Autheticator knows what are the <input>
names for the username and password? Shouldn't they be specified
somehow? (for this site, they are "LoginName" and "Password")

Below is my attempt using the Autheticator, but instead of
next_page being the string of the next page after a successful login,
it returned the front page of the site. So the method is not
successful. Do you have any idea what is wrong?

Many thanks!

Anthony

My Code
========
import java.net.*;
import java.io.*;

public class Test2 {

    private String login_url_str = "https://www.comsec.com.au/
Default.aspx";

    public Test2() {
    }

    public static void main(String[] args) {
        Test2 test1 = new Test2();
        test1.execute();
    }

    private void execute() {
        //Setup for https
        java.security.Security.addProvider(new
com.sun.net.ssl.internal.ssl.
                                   Provider());
        System.setProperty("java.protocol.handler.pkgs",
                   "com.sun.net.ssl.internal.www.protocol");

        Authenticator.setDefault( new MyAuthenticator() );

        try {
            URL url = new URL(login_url_str);
            //For handling POST request
            String next_page = getURLPostString(url,"");
            System.out.println(next_page);

        } catch (IOException ex) {
            System.out.println(ex);
            System.exit(1);
        }

    }

    /** Post a string to an URL and get the reply as a string. Returns
an empty
     string if things didn't work out. */
    //code from: http://martin.nobilitas.com/java/cookies.html
    private String getURLPostString(URL url, String body) {
        StringBuffer sb = new StringBuffer();

        // find the newline character(s) on the current system
        String newline = null;
        try {
            newline = System.getProperty("line.separator");
        } catch (Exception e) {
            newline = "\n";
        }

        try {
            // URL must use the http protocol!
            HttpURLConnection conn = (HttpURLConnection)
url.openConnection();

            conn.setRequestMethod("POST");
            conn.setAllowUserInteraction(false); // you may not ask
the user
            conn.setDoOutput(true); // we want to send things
            // the Content-type should be default, but we set it
anyway
            conn.setRequestProperty("Content-type",
                                    "application/x-www-form-
urlencoded");
            // the content-length should not be necessary, but we're
cautious
            conn.setRequestProperty("Content-length",
                                    Integer.toString(body.length()));

            // get the output stream to POST our form data
            OutputStream rawOutStream = conn.getOutputStream();
            PrintWriter pw = new PrintWriter(rawOutStream);

            pw.print(body); // here we "send" our body!
            pw.flush();
            pw.close();

            // get the input stream for reading the reply
            // IMPORTANT! Your body will not get transmitted if you
get the
            // InputStream before completely writing out your output
first!
            InputStream rawInStream = conn.getInputStream();

            // get response
            BufferedReader rdr = new BufferedReader(new
InputStreamReader(
                    rawInStream));
            String line;

            while ((line = rdr.readLine()) != null) {
                sb.append(line);
                sb.append(newline);
            }
            return sb.toString();
        } catch (Exception e) {
            System.out.println("Exception " + e.toString());
            e.printStackTrace();
        }
        return ""; // an exception occurred
    }

}

class MyAuthenticator extends Authenticator
   {
   /**
   * Called when password authorization is needed.
   * @return The PasswordAuthentication collected from the
   * user, or null if none is provided.
   */
   protected PasswordAuthentication getPasswordAuthentication()
      {
      return new PasswordAuthentication ( "usernameblah",
"passwordblah".toCharArray() );
      }
   }