WebClient - Client application that can talk interactively to Web servers. Requires the components listed below
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<requestheaders .length; i++) {
requestHeaders[i] = null;
}
int headerNum = 0;
String header =
requestHeadersArea.getText();
StringTokenizer tok =
new StringTokenizer(header, "rn");
while (tok.hasMoreTokens()) {
requestHeaders[headerNum++] = tok.nextToken();
}
}
}
HttpClient.java Handles the underlying network communication.
import java.net.*;
import java.io.*;
import javax.swing.*;
/** The underlying network client used by WebClient.
*
* 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 HttpClient extends NetworkClient {
private String requestLine;
private String[] requestHeaders;
private JTextArea outputArea;
private Interruptible app;
public HttpClient(String host, int port,
String requestLine, String[] requestHeaders,
JTextArea outputArea, Interruptible app) {
super(host, port);
this.requestLine = requestLine;
this.requestHeaders = requestHeaders;
this.outputArea = outputArea;
this.app = app;
if (checkHost(host)) {
connect();
}
}
protected void handleConnection(Socket uriSocket)
throws IOException {
try {
PrintWriter out = SocketUtil.getWriter(uriSocket);
BufferedReader in = SocketUtil.getReader(uriSocket);
outputArea.setText("");
out.println(requestLine);
for(int i=0; i<requestHeaders.length; i++) {
if (requestHeaders[i] == null) {
break;
} else {
out.println(requestHeaders[i]);
}
}
out.println();
String line;
while ((line = in.readLine()) != null &&
!app.isInterrupted()) {
outputArea.append(line + "n");
}
if (app.isInterrupted()) {
outputArea.append("---- Download Interrupted ----");
}
} catch(Exception e) {
outputArea.setText("Error: " + e);
}
}
private boolean checkHost(String host) {
try {
InetAddress.getByName(host);
return(true);
} catch(UnknownHostException uhe) {
outputArea.setText("Bogus host: " + host);
return(false);
}
}
}
LabeledTextField.java A labeled text field for the WebClient graphical user interface.
import java.awt.*; // For FlowLayout, Font.
import javax.swing.*;
/** A TextField with an associated Label.
*
* 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 LabeledTextField extends JPanel {
private JLabel label;
private JTextField textField;
public LabeledTextField(String labelString,
Font labelFont,
int textFieldSize,
Font textFont) {
setLayout(new FlowLayout(FlowLayout.LEFT));
label = new JLabel(labelString, JLabel.RIGHT);
if (labelFont != null) {
label.setFont(labelFont);
}
add(label);
textField = new JTextField(textFieldSize);
if (textFont != null) {
textField.setFont(textFont);
}
add(textField);
}
public LabeledTextField(String labelString,
String textFieldString) {
this(labelString, null, textFieldString,
textFieldString.length(), null);
}
public LabeledTextField(String labelString,
int textFieldSize) {
this(labelString, null, textFieldSize, null);
}
public LabeledTextField(String labelString,
Font labelFont,
String textFieldString,
int textFieldSize,
Font textFont) {
this(labelString, labelFont,
textFieldSize, textFont);
textField.setText(textFieldString);
}
/** The Label at the left side of the LabeledTextField.
* To manipulate the Label, do:
*
* 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);
}
}
Note: Brought from our old site: http://www.salearningschool.com/example_codes/ on Jan 2nd, 2017 From: http://sitestree.com/?p=10234
Categories:Programming Code Examples, Java/J2EE/J2ME, Network Programming
Tags:Java/J2EE/J2MENetwork Programming
Post Data:2017-01-02 16:04:28
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