import java.awt.*; // For BorderLayout, GridLayout, Font, Color.
import java.awt.event.*;
import java.util.*;
import javax.swing.*;

/** A graphical client that lets you interactively connect to
 *  Web servers and send custom request lines and
 *  request headers.
 *
 *  Taken from Core Web Programming from
 *  Prentice Hall and Sun Microsystems Press,
 *  .
 *  © 2001 Marty Hall and Larry Brown;
 *  may be freely used or adapted.
 */

public class WebClient extends JPanel
    implements Runnable, Interruptible, ActionListener {
  public static void main(String[] args) {
    WindowUtilities.setNativeLookAndFeel();
    WindowUtilities.openInJFrame(new WebClient(), 600, 700,
                                 "Web Client",
                                 SystemColor.control);
  }

  private LabeledTextField hostField, portField,
          requestLineField;
  private JTextArea requestHeadersArea, resultArea;
  private String host, requestLine;
  private int port;
  private String[] requestHeaders = new String[30];
  private JButton submitButton, interruptButton;
  private boolean isInterrupted = false;

  public WebClient() {
    setLayout(new BorderLayout(5, 30));
    int fontSize = 14;
    Font labelFont =
      new Font("Serif", Font.BOLD, fontSize);
    Font headingFont =
      new Font("SansSerif", Font.BOLD, fontSize+4);
    Font textFont =
      new Font("Monospaced", Font.BOLD, fontSize-2);
    JPanel inputPanel = new JPanel();
    inputPanel.setLayout(new BorderLayout());
    JPanel labelPanel = new JPanel();
    labelPanel.setLayout(new GridLayout(4,1));
    hostField = new LabeledTextField("Host:", labelFont,
                                     30, textFont);
    portField = new LabeledTextField("Port:", labelFont,
                                     "80", 5, textFont);
    // Use HTTP 1.0 for compatibility with the most servers.
    // If you switch this to 1.1, you *must* supply a
    // Host: request header.
    requestLineField =
      new LabeledTextField("Request Line:", labelFont,
                           "GET / HTTP/1.0", 50, textFont);
    labelPanel.add(hostField);
    labelPanel.add(portField);
    labelPanel.add(requestLineField);
    JLabel requestHeadersLabel =
      new JLabel("Request Headers:");
    requestHeadersLabel.setFont(labelFont);
    labelPanel.add(requestHeadersLabel);
    inputPanel.add(labelPanel, BorderLayout.NORTH);
    requestHeadersArea = new JTextArea(5, 80);
    requestHeadersArea.setFont(textFont);
    JScrollPane headerScrollArea =
      new JScrollPane(requestHeadersArea);
    inputPanel.add(headerScrollArea, BorderLayout.CENTER);
    JPanel buttonPanel = new JPanel();
    submitButton = new JButton("Submit Request");
    submitButton.addActionListener(this);
    submitButton.setFont(labelFont);
    buttonPanel.add(submitButton);
    inputPanel.add(buttonPanel, BorderLayout.SOUTH);
    add(inputPanel, BorderLayout.NORTH);
    JPanel resultPanel = new JPanel();
    resultPanel.setLayout(new BorderLayout());
    JLabel resultLabel =
      new JLabel("Results", JLabel.CENTER);
    resultLabel.setFont(headingFont);
    resultPanel.add(resultLabel, BorderLayout.NORTH);
    resultArea = new JTextArea();
    resultArea.setFont(textFont);
    JScrollPane resultScrollArea =
      new JScrollPane(resultArea);
    resultPanel.add(resultScrollArea, BorderLayout.CENTER);
    JPanel interruptPanel = new JPanel();
    interruptButton = new JButton("Interrupt Download");
    interruptButton.addActionListener(this);
    interruptButton.setFont(labelFont);
    interruptPanel.add(interruptButton);
    resultPanel.add(interruptPanel, BorderLayout.SOUTH);
    add(resultPanel, BorderLayout.CENTER);
  }

  public void actionPerformed(ActionEvent event) {
    if (event.getSource() == submitButton) {
      Thread downloader = new Thread(this);
      downloader.start();
    } else if (event.getSource() == interruptButton) {
      isInterrupted = true;
    }
  }

  public void run() {
    isInterrupted = false;
    if (hasLegalArgs())
      new HttpClient(host, port, requestLine,
             requestHeaders, resultArea, this);
  }

  public boolean isInterrupted() {
    return(isInterrupted);
  }

  private boolean hasLegalArgs() {
    host = hostField.getTextField().getText();
    if (host.length() == 0) {
      report("Missing hostname");
      return(false);
    }
    String portString =
      portField.getTextField().getText();
    if (portString.length() == 0) {
      report("Missing port number");
      return(false);
    }
    try {
      port = Integer.parseInt(portString);
    } catch(NumberFormatException nfe) {
      report("Illegal port number: " + portString);
      return(false);
    }
    requestLine =
      requestLineField.getTextField().getText();
    if (requestLine.length() == 0) {
      report("Missing request line");
      return(false);
    }
    getRequestHeaders();
    return(true);
  }

  private void report(String s) {
    resultArea.setText(s);
  }

  private void getRequestHeaders() {
    for(int i=0; i
   *    LabeledTextField ltf = new LabeledTextField(...);
   *    ltf.getLabel().someLabelMethod(...);
   *

*/ public JLabel getLabel() { return(label); } /** The TextField at the right side of the * LabeledTextField. */ public JTextField getTextField() { return(textField); } } Interruptible.java Polls to see if the user choose to interrupt the current network download. /** An interface for classes that can be polled to see * if they’ve been interrupted. Used by HttpClient * and WebClient to allow the user to interrupt a network * download. * * Taken from Core Web Programming from * Prentice Hall and Sun Microsystems Press, * . * © 2001 Marty Hall and Larry Brown; * may be freely used or adapted. */ public interface Interruptible { public boolean isInterrupted(); } NetworkClient.java Starting point for a network client to communicate with a remote computer. import java.net.*; import java.io.*; /** A starting point for network clients. You’ll need to * override handleConnection, but in many cases connect can * remain unchanged. It uses SocketUtil to simplify the * creation of the PrintWriter and BufferedReader. * * Taken from Core Web Programming from * Prentice Hall and Sun Microsystems Press, * © 2001 Marty Hall and Larry Brown; * may be freely used or adapted. */ public class NetworkClient { protected String host; protected int port; /** Register host and port. The connection won’t * actually be established until you call * connect. */ public NetworkClient(String host, int port) { this.host = host; this.port = port; } /** Establishes the connection, then passes the socket * to handleConnection. */ public void connect() { try { Socket client = new Socket(host, port); handleConnection(client); } catch(UnknownHostException uhe) { System.out.println(“Unknown host: ” + host); uhe.printStackTrace(); } catch(IOException ioe) { System.out.println(“IOException: ” + ioe); ioe.printStackTrace(); } } /** This is the method you will override when * making a network client for your task. * The default version sends a single line * (“Generic Network Client”) to the server, * reads one line of response, prints it, then exits. */ protected void handleConnection(Socket client) throws IOException { PrintWriter out = SocketUtil.getWriter(client); BufferedReader in = SocketUtil.getReader(client); out.println(“Generic Network Client”); System.out.println (“Generic Network Client:\n” + “Made connection to ” + host + ” and got ‘” + in.readLine() + “‘ in response”); client.close(); } /** The hostname of the server we’re contacting. */ public String getHost() { return(host); } /** The port connection will be made on. */ public int getPort() { return(port); } } SocketUtil.java: Provides utilities for wrapping a BufferedReader and PrintWriter around the Socket’s input and output streams, respectively. import java.net.*; import java.io.*; /** A shorthand way to create BufferedReaders and * PrintWriters associated with a Socket. * * Taken from Core Web Programming from * Prentice Hall and Sun Microsystems Press, * . * © 2001 Marty Hall and Larry Brown; * may be freely used or adapted. */ public class SocketUtil { /** Make a BufferedReader to get incoming data. */ public static BufferedReader getReader(Socket s) throws IOException { return(new BufferedReader( new InputStreamReader(s.getInputStream()))); } /** Make a PrintWriter to send outgoing data. * This PrintWriter will automatically flush stream * when println is called. */ public static PrintWriter getWriter(Socket s) throws IOException { // Second argument of true means autoflush. return(new PrintWriter(s.getOutputStream(), true)); } } WindowUtilities.java Simplifies the setting of native look and feel. import javax.swing.*; import java.awt.*; // For Color and Container classes. /** A few utilities that simplify using windows in Swing. * * Taken from Core Web Programming from * Prentice Hall and Sun Microsystems Press, * © 2001 Marty Hall and Larry Brown; * may be freely used or adapted. */ public class WindowUtilities { /** Tell system to use native look and feel, as in previous * releases. Metal (Java) LAF is the default otherwise. */ public static void setNativeLookAndFeel() { try { UIManager.setLookAndFeel( UIManager.getSystemLookAndFeelClassName()); } catch(Exception e) { System.out.println(“Error setting native LAF: ” + e); } } public static void setJavaLookAndFeel() { try { UIManager.setLookAndFeel( UIManager.getCrossPlatformLookAndFeelClassName()); } catch(Exception e) { System.out.println(“Error setting Java LAF: ” + e); } } public static void setMotifLookAndFeel() { try { UIManager.setLookAndFeel( “com.sun.java.swing.plaf.motif.MotifLookAndFeel”); } catch(Exception e) { System.out.println(“Error setting Motif LAF: ” + e); } } /** A simplified way to see a JPanel or other Container. Pops * up a JFrame with specified Container as the content pane. */ public static JFrame openInJFrame(Container content, int width, int height, String title, Color bgColor) { JFrame frame = new JFrame(title); frame.setBackground(bgColor); content.setBackground(bgColor); frame.setSize(width, height); frame.setContentPane(content); frame.addWindowListener(new ExitListener()); frame.setVisible(true); return(frame); } /** Uses Color.white as the background color. */ public static JFrame openInJFrame(Container content, int width, int height, String title) { return(openInJFrame(content, width, height, title, Color.white)); } /** Uses Color.white as the background color, and the * name of the Container’s class as the JFrame title. */ public static JFrame openInJFrame(Container content, int width, int height) { return(openInJFrame(content, width, height, content.getClass().getName(), Color.white)); } } ExitListener.java WindowListener for applications in this chapter. import java.awt.*; import java.awt.event.*; /** A listener that you attach to the top-level JFrame of * your application, so that quitting the frame exits the * application. * * Taken from Core Web Programming from * Prentice Hall and Sun Microsystems Press, * © 2001 Marty Hall and Larry Brown; * may be freely used or adapted. */ public class ExitListener extends WindowAdapter { public void windowClosing(WindowEvent event) { System.exit(0); } }