/*
* 1.0 code.
*/
import java.applet.Applet;
import java.awt.*;
import java.io.*;
import java.net.*;
import java.util.*;
public class TalkClientApplet extends Applet implements Runnable {
Socket socket;
DataOutputStream os;
DataInputStream is;
TextField portField, message;
TextArea display;
Button button;
int dataPort;
boolean trysted;
Thread receiveThread;
String host;
boolean DEBUG = false;
public void init() {
//Get the address of the host we came from.
host = getCodeBase().getHost();
//Set up the UI.
GridBagLayout gridBag = new GridBagLayout();
GridBagConstraints c = new GridBagConstraints();
setLayout(gridBag);
message = new TextField("");
c.fill = GridBagConstraints.HORIZONTAL;
c.gridwidth = GridBagConstraints.REMAINDER;
gridBag.setConstraints(message, c);
add(message);
display = new TextArea(10, 40);
display.setEditable(false);
c.weightx = 1.0;
c.weighty = 1.0;
c.fill = GridBagConstraints.BOTH;
gridBag.setConstraints(display, c);
add(display);
Label l = new Label("Enter the port (on host " + host
+ ") to send the request to:",
Label.RIGHT);
c.fill = GridBagConstraints.HORIZONTAL;
c.gridwidth = 1;
c.weightx = 0.0;
c.weighty = 0.0;
gridBag.setConstraints(l, c);
add(l);
portField = new TextField(6);
c.fill = GridBagConstraints.NONE;
gridBag.setConstraints(portField, c);
add(portField);
button = new Button("Connect");
gridBag.setConstraints(button, c);
add(button);
validate();
}
public synchronized void start() {
if (DEBUG) {
System.out.println("In start() method.");
}
if (receiveThread == null) {
trysted = false;
portField.setEditable(true);
button.enable();
os = null;
is = null;
socket = null;
receiveThread = new Thread(this);
receiveThread.start();
if (DEBUG) {
System.out.println(" Just set everything to null and started thread.");
}
} else if (DEBUG) {
System.out.println(" receiveThread not null! Did nothing!");
}
}
public synchronized void stop() {
if (DEBUG) {
System.out.println("In stop() method.");
}
receiveThread = null;
trysted = false;
portField.setEditable(true);
button.enable();
notify();
try { //Close input stream.
if (is != null) {
is.close();
is = null;
}
} catch (Exception e) {} //Ignore exceptions.
try { //Close output stream.
if (os != null) {
os.close();
os = null;
}
} catch (Exception e) {} //Ignore exceptions.
try { //Close socket.
if (socket != null) {
socket.close();
socket = null;
}
} catch (Exception e) {} //Ignore exceptions.
}
public Insets insets() {
return new Insets(4,4,5,5);
}
public void paint(Graphics g) {
Dimension d = size();
Color bg = getBackground();
g.setColor(bg);
g.draw3DRect(0, 0, d.width - 1, d.height - 1, true);
g.draw3DRect(3, 3, d.width - 7, d.height - 7, false);
}
public synchronized boolean action(Event event, Object arg) {
int port;
if (DEBUG) {
System.out.println("In action() method.");
}
if (receiveThread == null) {
start();
}
if (!trysted) {
//We need to attempt a rendezvous.
if (DEBUG) {
System.out.println(" trysted = false. "
+ "About to attempt a rendezvous.");
}
//Get the port the user entered...
try {
port = Integer.parseInt(portField.getText());
} catch (NumberFormatException e) {
//No integer entered.
display.appendText("Please enter an integer below.\n");
return true;
}
//...and rendezvous with it.
rendezvous(port);
} else { //We've already rendezvoused. Just send data over.
if (DEBUG) {
System.out.println(" trysted = true. "
+ "About to send data.");
}
String str = message.getText();
message.selectAll();
try {
os.writeUTF(str);
os.flush();
} catch (IOException e) {
display.appendText("ERROR: Applet couldn't write to socket.\n");
display.appendText("...Disconnecting.\n");
stop();
return true;
} catch (NullPointerException e) {
display.appendText("ERROR: No output stream!\n");
display.appendText("...Disconnecting.\n");
stop();
return true;
}
display.appendText("Sent: " + str + "\n");
}
return true;
}
synchronized void waitForTryst() {
//Wait for notify() call from action().
try {
wait();
} catch (InterruptedException e) {}
if (DEBUG) {
System.out.println("waitForTryst about to return. "
+ "trysted = " + trysted + ".");
}
return;
}
public void run() {
String received = null;
waitForTryst();
//OK, now we can send messages.
while (Thread.currentThread() == receiveThread) {
try {
//Wait for data from the server.
received = is.readUTF();
//Display it.
if (received != null) {
display.appendText("Received: " + received + "\n");
} else { //success but no data...
System.err.println("readUTF() returned no data");
}
} catch (EOFException e) { //Stream has no more data.
display.appendText("NOTE: Other applet is disconnected.\n");
//display.appendText("...Disconnecting.\n");
//stop();
return;
} catch (NullPointerException e) { //Stream doesn't exist.
display.appendText("NOTE: Disconnected from server.\n");
display.appendText("...Completing disconnect.\n");
stop();
return;
} catch (IOException e) { //Perhaps a temporary problem?
display.appendText("NOTE: Couldn't read from socket.\n");
//display.appendText("...Disconnecting.\n");
//stop();
return;
} catch (Exception e) { //Unknown error. Throw tantrum.
display.appendText("ERROR: Couldn't read from socket.\n");
display.appendText("...Disconnecting.\n");
System.err.println("Couldn't read from socket.");
e.printStackTrace();
stop();
return;
}
}
}
private void rendezvous(int port) {
//Try to open a socket to the port.
try {
socket = new Socket(host, port);
} catch (UnknownHostException e) {
display.appendText("ERROR: Can't find host: " + host + ".\n");
return;
} catch (IOException e) {
display.appendText("ERROR: Can't open socket on rendezvous port "
+ port + " (on host " + host + ").\n");
return;
}
//Try to open streams to read and write from the socket.
try {
os = new DataOutputStream(socket.getOutputStream());
is = new DataInputStream(socket.getInputStream());
} catch (IOException e) {
display.appendText("ERROR: Created data socket but can't "
+ "open stream on it.\n");
display.appendText("...Disconnecting.\n");
stop();
return;
}
if ((os != null) & (is != null)) {
if (DEBUG) {
System.out.println("Successful rendezvous.");
System.out.println("socket = " + socket);
System.out.println("output stream = " + os);
System.out.println("input stream = " + is);
}
//Let the main applet thread know we've successfully rendezvoused.
portField.setEditable(false);
button.disable();
trysted = true;
notify();
} else {
display.appendText("ERROR: Port is valid but communication failed. "
+ "Please TRY AGAIN.\n");
}
}
}
|
