use a scanner in Java
This is more Java than Java - Linux, but I'd appreciate your answer: Does anybody know if there's a way to use a scanner in Java ? One of my Java programs is calling a Visual Basic program that scans & saves an image, but it's not very fast so I'm trying to sinf a 100% Java solution. Thanks, Lucas
waitFor after exec never returns
Sometimes, when I create a process with Runtime.exec, waitFor never
returns, even though I'm clearing the error and output streams.
Here is my code, with important lines starred:
static void shexec(String command) throws
InternalErrorException {
String[]
commandArray = {"/bin/sh", "-c", command};
String[]
envArray = {"TERM=vt100"};
Log.logMessage("About
to call exec");
try
{
Log.logMessage("/bin/sh -c " + command);
Process p =
Runtime.getRuntime().exec(commandArray, envArray);
InputStream is = p.getErrorStream();
byte cbuf[] = new byte[1024];
int len;
while ((len = is.read(cbuf, 0, 1024)) != -1) {
if
(len > 0) {
String errorMessage = new String(cbuf, 0, len);
Log.logMessage("Read " + len + " bytes from
ErrorStream:" + errorMessage);
throw new InternalErrorException(errorMessage);
}
}
Log.logMessage("Done with ErrorStream");
is = p.getInputStream();
while ((len = is.read(cbuf, 0, 1024)) != -1)
Log.logMessage("Read
" + len + " bytes from InputStream");
Log.logMessage("Done with InputStream");
p.getOutputStream().close();
Log.logMessage("About to call waitFor");
p.waitFor();
Log.logMessage("Return value is " + p.exitValue());
Log.logMessage("Back from waitFor");
} catch (Exception e) {
Log.logMessage("Exception occurred: " + e);
throw new InternalErrorException(e);
}
}
My log file reads:
About to call exec
/bin/sh -c lynx -dump -force_html
/home/systers/javamlm/archive/94.text-html >
/home/systers/javamlm/archive/94.text-plain
Done with ErrorStream
Done with InputStream
About to call waitFor
I am using:
java version "1.3.0"
Java(TM) 2 Runtime Environment, Standard Edition (build
Blackdown-1.3.0-FCS)
Java HotSpot(TM) Client VM (build Blackdown-1.3.0-FCS, mixed mode)
ps shows the process as being defunct.
This has been frustrating me for a long time.
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Blackdown JDK1.3.1?
Hi Blackdown Developers. Will you be releasing a version of JDK1.3.1 with maybe some of the deficiences of Sun's just-released version corrected? In particular: Support for KDE2: http://lists.kde.org/?l=kde-core-devel&m=98562599002412&w=2 http://lists.kde.org/?l=kde-core-devel&m=98588662130333&w=2 and avoiding regressions like: http://java.sun.com/j2se/1.3/relnotes.html#awt "Bug 4199374 concerns a focus management problem with JWindow objects. In particular, this bug prevents Component.requestFocus() from giving focus to components in a JWindow. This bug was fixed in update releases J2SDK 1.2.2_05 and J2SDK 1.3.0_02. However, it is not fixed in J2SDK 1.3.1." Regards, Scott Langley [EMAIL PROTECTED] http://www.scottlangley.com __ FREE Personalized Email at Mail.com Sign up at http://www.mail.com/?sr=signup -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: waitFor after exec never returns
On Fri, 18 May 2001, Ellen Spertus wrote:
> Sometimes, when I create a process with Runtime.exec, waitFor never
> returns, even though I'm clearing the error and output streams. Here is
> my code, with important lines starred:
>
[snip]
> String[] commandArray = {"/bin/sh", "-c", command};
>
> My log file reads:
> About to call exec
> /bin/sh -c lynx -dump -force_html
> /home/systers/javamlm/archive/94.text-html >
> /home/systers/javamlm/archive/94.text-plain
> Done with ErrorStream
> Done with InputStream
> About to call waitFor
When I invoke lynx the say way the code does, lynx goes into full-screen
mode. It isn't writing to stdout via the shell's redirect, it' using
ncurses to manipulate my screen.
When I invoke lynx without the shell, it writes to stdout as expected.
Lynx isn't a shell script, you can invoke it directly in the exec() call.
--
Joi EllisSoftware Engineer
Aravox Technologies [EMAIL PROTECTED], [EMAIL PROTECTED]
No matter what we think of Linux versus FreeBSD, etc., the one thing I
really like about Linux is that it has Microsoft worried. Anything
that kicks a monopoly in the pants has got to be good for something.
- Chris Johnson
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Re: waitFor after exec never returns
Thanks for the reply. >Lynx isn't a shell script, you can invoke it directly in the exec() call. The reason I don't invoke lynx directly is because I am redirecting its output to a file, which of course requires a shell. I think that was obscured by some bad line breaks in my original message. Let's see if this is any clearer: /bin/sh -c lynx -dump -force_html 94.text-html > 94.text-plain Ellen -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: waitFor after exec never returns
On Fri, 18 May 2001, Ellen Spertus wrote: > Thanks for the reply. > > >Lynx isn't a shell script, you can invoke it directly in the exec() call. > > The reason I don't invoke lynx directly is because I am redirecting its > output to a file, which of course requires a shell. I think that was > obscured by some bad line breaks in my original message. Let's see if this > is any clearer: > > /bin/sh -c lynx -dump -force_html 94.text-html > 94.text-plain > Yes, I noticed the redirection. Have you actually LOOKED at 94.text-plain when you invoke this command string manually? Lynx is going into ncurses mode because it's confused. lynx -dump -force_html 94.text-html > 94.text-plain does exactly what you want. /bin/sh -c lynx -dump -force_html 94.text-html > 94.text-plain does not. -- Joi EllisSoftware Engineer Aravox Technologies [EMAIL PROTECTED], [EMAIL PROTECTED] No matter what we think of Linux versus FreeBSD, etc., the one thing I really like about Linux is that it has Microsoft worried. Anything that kicks a monopoly in the pants has got to be good for something. - Chris Johnson -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: waitFor after exec never returns
At 03:31 PM 5/18/2001 -0500, you wrote: >Yes, I noticed the redirection. Have you actually LOOKED at 94.text-plain >when you invoke this command string manually? It generates the right output when I can lynx directly but not when I pass it through a shell. I hadn't realized that lynx would behave differently depending how it was invoked, as long as environment variables were set properly. Thanks for pointing that out. > lynx -dump -force_html 94.text-html > 94.text-plain > >does exactly what you want. Yes, but I can't give that as an argument to Runtime.exec, because it includes redirection. Do you know how to get lynx to do what I want (convert a html file into text)? Ellen Spertus -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: waitFor after exec never returns
At 09:57 PM 5/18/2001 -0500, Joi Ellis wrote: >Lynx is writing the rendered text to stdout, which you're reading and >throwing away. Why not read it and write it to the file yourself? I thought doing it with redirection would be simpler, but apparently not. I rewrote it so my program grabs the lynx output directly, and all works. I still get a hang on p.waitFor, so I replaced it with p.destroy (after I've read the strings). I'd still like to know why waitFor isn't working, but I'm happy my program is running. Thanks for your assistance. Ellen -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
Re: waitFor after exec never returns
Ellen Spertus wrote: > At 09:57 PM 5/18/2001 -0500, Joi Ellis wrote: > >Lynx is writing the rendered text to stdout, which you're reading and > >throwing away. Why not read it and write it to the file yourself? > > I thought doing it with redirection would be simpler, but apparently > not. I rewrote it so my program grabs the lynx output directly, and all > works. I still get a hang on p.waitFor, so I replaced it with p.destroy > (after I've read the strings). I'd still like to know why waitFor isn't > working, but I'm happy my program is running. Lynx is probably sitting there waiting for input. Closing the stream to its stdin (Process.getOutputStream().close()) might help it decide to terminate. Nathan > > > Thanks for your assistance. > > Ellen > > -- > To UNSUBSCRIBE, email to [EMAIL PROTECTED] > with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED] -- To UNSUBSCRIBE, email to [EMAIL PROTECTED] with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
