HttpChatAppletpublic class HttpChatApplet extends Applet implements Runnable
| Fields Summary |
|---|
| TextArea | text | | Label | label | | TextField | input | | Thread | thread | | String | user |
| Methods Summary |
|---|
| void | broadcastMessage(java.lang.String message)
message = user + ": " + message; // Pre-pend the speaker's name
try {
URL url = new URL(getCodeBase(), "/servlet/ChatServlet");
HttpMessage msg = new HttpMessage(url);
Properties props = new Properties();
props.put("message", message);
msg.sendPostMessage(props);
}
catch (SocketException e) {
// Can't connect to host, report it and abandon the broadcast
System.out.println("Can't connect to host: " + e.getMessage());
}
catch (FileNotFoundException e) {
// Servlet doesn't exist, report it and abandon the broadcast
System.out.println("Resource not found: " + e.getMessage());
}
catch (Exception e) {
// Some other problem, report it and abandon the broadcast
System.out.println("General exception: " +
e.getClass().getName() + ": " + e.getMessage());
}
| | java.lang.String | getNextMessage()
String nextMessage = null;
while (nextMessage == null) {
try {
URL url = new URL(getCodeBase(), "/servlet/ChatServlet");
HttpMessage msg = new HttpMessage(url);
InputStream in = msg.sendGetMessage();
DataInputStream data = new DataInputStream(
new BufferedInputStream(in));
nextMessage = data.readLine();
}
catch (SocketException e) {
// Can't connect to host, report it and wait before trying again
System.out.println("Can't connect to host: " + e.getMessage());
try { Thread.sleep(5000); } catch (InterruptedException ignored) { }
}
catch (FileNotFoundException e) {
// Servlet doesn't exist, report it and wait before trying again
System.out.println("Resource not found: " + e.getMessage());
try { Thread.sleep(5000); } catch (InterruptedException ignored) { }
}
catch (Exception e) {
// Some other problem, report it and wait before trying again
System.out.println("General exception: " +
e.getClass().getName() + ": " + e.getMessage());
try { Thread.sleep(1000); } catch (InterruptedException ignored) { }
}
}
return nextMessage + "\n";
| | public boolean | handleEvent(java.awt.Event event)
switch (event.id) {
case Event.ACTION_EVENT:
if (event.target == input) {
broadcastMessage(input.getText());
input.setText("");
return true;
}
}
return false;
| | public void | init()
// Check if this applet was loaded directly from the filesystem.
// If so, explain to the user that this applet needs to be loaded
// from a server in order to communicate with that server's servlets.
URL codebase = getCodeBase();
if (!"http".equals(codebase.getProtocol())) {
System.out.println();
System.out.println("*** Whoops! ***");
System.out.println("This applet must be loaded from a web server.");
System.out.println("Please try again, this time fetching the HTML");
System.out.println("file containing this servlet as");
System.out.println("\"http://server:port/file.html\".");
System.out.println();
System.exit(1); // Works only from appletviewer
// Browsers throw an exception and muddle on
}
// Get this user's name from an applet parameter set by the servlet
// We could just ask the user, but this demonstrates a
// form of servlet->applet communication.
user = getParameter("user");
if (user == null) user = "anonymous";
// Set up the user interface...
// On top, a large TextArea showing what everyone's saying.
// Underneath, a labeled TextField to accept this user's input.
text = new TextArea();
text.setEditable(false);
label = new Label("Say something: ");
input = new TextField();
input.setEditable(true);
setLayout(new BorderLayout());
Panel panel = new Panel();
panel.setLayout(new BorderLayout());
add("Center", text);
add("South", panel);
panel.add("West", label);
panel.add("Center", input);
| | public void | run()
while (true) {
text.appendText(getNextMessage());
}
| | public void | start()
thread = new Thread(this);
thread.start();
| | public void | stop()
thread.stop();
thread = null;
|
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