Java start new Process (Browser) and notice when Browser Window is closed.

Java start new Process (Browser) and notice when Browser Window is closed.

Post by Peter.wei » Sat, 16 Sep 2006 21:22:33


ello,

I have a java programm which shall open a Browser with a certain URL
AND!!!!! if this browser window is closed from a use after a while, the
java programm should be informed about this.

The following code is what I did. I am able to open a browser OS
independently.
--------------------------------------------------------------------------------------------------------------------
package com.indatex.browsercommunication;
import java.io.*;
/* Note - you must include the url type -- either "http://" or
* "file://".
*/
public class BrowserControlOSIndependent
{
// Used to identify the windows platform.
private String WIN_ID = "Windows";
// The default system browser under windows.
private String WIN_PATH = "rundll32";
// The flag to display a url.
private String WIN_FLAG = "url.dll,FileProtocolHandler";
// The default browser under unix.
private String UNIX_PATH = "netscape";
// The flag to display a url.
private String UNIX_FLAG = "-remote openURL";
private Process p = null;

public boolean hasBrowserFinished()throws Exception{
if(p.exitValue()>0){
return true;
}
p.destroy();
return false;
}

public void displayURL(String url)
{
boolean windows = isWindowsPlatform();
String cmd = null;
try
{
if (windows)
{
// cmd = 'rundll32 url.dll,FileProtocolHandler
http://...'
cmd = WIN_PATH + " " + WIN_FLAG + " " + url;
p = Runtime.getRuntime().exec(cmd);
try {
p.waitFor();
} catch (InterruptedException e) {
// TODO Auto-generated catch
block
e.printStackTrace();
}
}
else
{
// Under Unix, Netscape has to be running for the
"-remote"
// command to work. So, we try sending the command and
// check for an exit value. If the exit command is 0,
// it worked, otherwise we need to start the browser.
// cmd = 'netscape -remote
openURL(http://www.javaworld.com)'
cmd = UNIX_PATH + " " + UNIX_FLAG + "(" + url + ")";
Process p = Runtime.getRuntime().exec(cmd);
try
{
// wait for exit code -- if it's 0, command worked,
// otherwise we need to start the browser up.
int exitCode = p.waitFor();
if (exitCode != 0)
{
// Command failed, start up the browser
// cmd = 'netscape http://www.javaworld.com'
cmd = UNIX_PATH + " " + url;
p = Runtime.getRuntime().exec(cmd);
}
}
catch(InterruptedException x)
{
System.err.println("Error bringing up browser,
cmd='" +
cmd + "'");
System.err.println("Caught: " + x);
}
}
}
catch(IOException x)
{
// couldn't exec browser
System.e
 
 
 

Java start new Process (Browser) and notice when Browser Window is closed.

Post by Andrew Tho » Sat, 16 Sep 2006 22:56:57


The URL being?


(snip example)

If the toddler trips over the plug and drops the computer, your
Java program will not be informed. I just wanted to make it
clear that it is *impossible* to guarantee that the application
would be informed.


Failing the above, and assuming all this is done with the
user's acitve consent (and trust) you might ..

Open a frames based web-page that has an applet in
one frame and the target document in another. The applet
send information via socket back to the application.

Every 0.nn milliseconds, the applet sends a message that
conforms it is active. If the signal has not been received in
2 x 0.nn ms, the application can assume the browser window
is closed.

Note that you might have to takes some extra precautions to
ensure that the the address of the page shown in the framed
web page has not changed (has the user clicked a link?).

HTH

Andrew T.

 
 
 

Java start new Process (Browser) and notice when Browser Window is closed.

Post by Peter.wei » Sun, 17 Sep 2006 01:23:51


Andrew Thompson schrieb:


Hello Andrew,
I try to make it more concret:

process = Runtime.getRuntime().exec ("rundll32
url.dll,FileProtocolHandler " + theUrl);

process.waitFor();
while(1==1){
if(process.exitValue() > 0){ //Process doesnt exist anymore
doSomething();
break;
}
}

The java programm (it is a component) starts, the loop is running, If I
close now the browser, the exitValue() is still 0!!

I simply dont understand. i have a variable of the process, the process
doesnt exist anymore (Browser Window closed from the user), why isn't
there a property in 'brower' which tells me "The process which a
reference is not alive anymore").

Have I been clear?

Thanks,
have a nice weekend,
Peter
 
 
 

Java start new Process (Browser) and notice when Browser Window is closed.

Post by Andrew Tho » Sun, 17 Sep 2006 01:43:36


I will read the problem carefully this time.


Yes. That seems relatively clear, but I am no expert in
processes, so I had better make no comment on that
aspect of the problem. OTOH - I still recommend that
this is the entirely *wrong* strategy for detecting the end
of the 'display of a web page' - is that not the real intent
here?

After all, after your Java process has displayed the URL
in my browser, I might then use that window to surf 'home',
and while your process still reposrts that the JVM that ran
the browser is still 'active' - you cannot be sure it is displaying
the correct page.

As an aside - what is the content of this URL?
Do you *control* (can edit) the content?
Why is it so important for your application to know
whether the content is still open for display?

(There are a number of alternate strategies you might
try for the end effect you want, but I still do not have
a clear idea of what it is you are trying to *achieve*
by all this.)

Andrew T.