Connecting to HTTP

• HTTP listens on port 80.
• So can we just open up a telnet session to 80 and see the HTML?  We sure can, as long as we know what to tell it.
• Follow the directions on page 200 in Core Java 2, Volume II, Advanced Features, to connect to java.sun.com.
• Try it with any other site, such as oz.uc.edu .
• You may have to enter 80 in the port drop down box to get this to work.
• Let's continue with this example and implement the SocketTest source on pages 200-201.  I've changed it a little bit to prompt the user for the domain name and port, but the rest is similar.
• Try it with time-A.timefreq.bldrdoc.gov and 13.  Watch the response.
• Then, try it with some garbage and note the exception.

/*
 * SocketResponse.java
 *
 * Created on April 29, 2002, 9:21 PM
 */

// Import the JOptionPane, io and net packages.
import java.io.*;
import java.net.*;
import javax.swing.JOptionPane;
/**
 *
 * @author  default
 */
public class SocketResponse {

    /** Creates a new instance of SocketResponse */
    public SocketResponse() {
    }
 
    /**
     * Prompt the user for host and port.
     * Create a connection and return the results.
     *
     */
 
    public void connect() {
 
        // Prompt the user for information.
        String host = JOptionPane.showInputDialog("Please enter the host to which you wish to connect.");
        String port = JOptionPane.showInputDialog("Please enter the port.");
 
        // try-catch block for possible exceptions.
        try {
            // Create a socket.
            Socket socket = new Socket(host, Integer.parseInt(port));
 
            // Create a buffered reader and input stream to read the response.
            // We can get the input stream from the socket, and we can pass that to the buffered reader
            // constructor.
            BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
            boolean moreData = true;
 
            // Read while we have information to read.
            while(moreData) {
                // Read a line from the buffered reader.
                String line = in.readLine();
 
                // Read the data, or let the loop know we're finished.
                if (line == null) {
                    moreData = false;
                } else {
                    System.out.println(line);
                } // end if.
            } // end for.
        // Handle exceptions.
        } catch (NumberFormatException e) {
            System.out.println("Enter the port as a number, please.  Message: " + e.getMessage());
            e.printStackTrace();
        } catch (IOException e) {
            System.out.println("IOException caught while attempting connection.  Message: " + e.getMessage());
            e.printStackTrace();
        }
    } // end connect()
 
    // The main method starts the program.
    public static void main(String args[]) {
        SocketResponse socketResponse = new SocketResponse();
        socketResponse.connect();
 
 
    }

}

 Implementing Servers

Created by:  Brandan Jones December 17, 2001