Is JAR signing by Java program possible?

I need to create (i.e. fix) JARs and I'd like to apply signatures to them by internal means, that is without the use of jarsigner.exe. I have a keystore file I want to use for the signature.
Which means does the JDK's API provide to implement this? I can't find usable classes (Keystore for instance doesn't seem to help one bit), but I cannot believe that they're not around.

>>
http://java.sun.com/docs/books/tutorial/security1.2/api
ign/gensig.html
http://java.sun.com/j2se/1.4.2/docs/guide/security/Cryp
oSpec.htmlThanks, helped quite a bit. So I overlooked the load()
method...Top Tip.
Try the example without RTFM. Any probs, post hem here.

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Writing into a jar file through Java program

Is there a way to get a file from a jar (for ex. a properties file) make changes to it on the fly and write the same file back to the jar through a Java program?

I cannnot give u exact code as i am bit busy..but i am giving close to exact
below is code for reading contents of jar file
import java.io.*;
import java.util.jar.*;
public class JarRead {
public static void main (String args[])
throws IOException {
if (args.length != 2) {
System.out.println(
"Please provide a JAR filename and file to read");
System.exit(-1);
JarFile jarFile = new JarFile(args[0]);
JarEntry entry = jarFile.getJarEntry(args[1]);
InputStream input = jarFile.getInputStream(entry);
process(input);
jarFile.close();
private static void process(InputStream input)
throws IOException {
InputStreamReader isr =
new InputStreamReader(input);
BufferedReader reader = new BufferedReader(isr);
String line;
while ((line = reader.readLine()) != null) {
System.out.println(line);
reader.close();
now here say u have test.jar which contains test.txt (file)
then
java JarRead test.jar test.txt
will print content of text.txt
now in ur case u write content of each file in some other file modify it there and then create a jar file from those files using jaroutput stream .....
this may not be all clear ..but what to do..bit busy...u are welcomed to make changes in above stratergy....n queries if any after using above stratergy and/or your great brain...

Executing Jar Application using Java Programs

Hello there,
How can I run a java application using java programs.
Desc:
public class someapp {
public static void main(String[] ext) {
// How can I execute a jar application from here through java code
}

You could use java.lang.Runtime.exec(). Another way could be loading the main class of the jar file and invoking its main method dynamically.

Running a .jar with a java program on unix

I am trying to run a jar file with this java code but when i run it, it comes up with built successfully but the file doesn't run.
ps- I use a unix os
public class Main {
public static void main(String args[]) throws IOException, InterruptedException {
// first method i tried:
Runtime.getRuntime().exec( new String[] {"/bin/sh", "-c",
"/Users/cb/NetBeansProjects/MultiCalc/dist/MultiCalc.jar output.out ascii workload2.trace 0"});
//second method i tried:
ProcessBuilder pb = new ProcessBuilder( new String[] {"/bin/sh", "-c",
"/Users/cb/NetBeansProjects/MultiCalc/dist/MultiCalc.jar"});
pb.redirectErrorStream( true );
pb.start();
thanks a lot in advance!

javalavaguava-- wrote:
I am trying to run a jar file with this java code but when i run it, it comes up with built successfully but the file doesn't run.
ps- I use a unix os
public class Main {
public static void main(String args[]) throws IOException, InterruptedException {
// first method i tried:
Runtime.getRuntime().exec( new String[] {"/bin/sh", "-c",
"/Users/cb/NetBeansProjects/MultiCalc/dist/MultiCalc.jar output.out ascii workload2.trace 0"});
//second method i tried:
ProcessBuilder pb = new ProcessBuilder( new String[] {"/bin/sh", "-c",
"/Users/cb/NetBeansProjects/MultiCalc/dist/MultiCalc.jar"});
pb.redirectErrorStream( true );
pb.start();
thanks a lot in advance!I don't see any mention of 'java' when trying to execute the jar file. You have to specify which application should process a jar file - it doesn't magically know to use java.
P.S. You should read the 4 sections of [http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html|http://www.javaworld.com/javaworld/jw-12-2000/jw-1229-traps.html] and implement ALL the recommendations.

Updating jar from a java program

I have a text file in a jar. The contents of the file change during program execution and so, I need to be able to update the jar to reflect the changed contents. How do I do this from inside my program?
Ravi

There is no way to "update" a jar file. If you want to do that, you must create an entirely new jar file containing the modified data. So, you should only store permanent data in a jar file.

Running executable jar from within a java program

Is there a way to launch an executable jar in a java program? I tried wrapping the jar in an exe and calling it using Runtime exec() and though this approach works it does only for windows. I want it to work for unix/linux too.

jaki wrote:
Yes, but it's a sub process.Nope.
Hence the calling process doesn't quit unless the called one returns.Wrong.
My calling program is actually a jar and what Im trying to do is delete the jar after it's done running. But the above method (of launching a separate jar doing the deletion) doesn't seem to work for the above mentioned reason.Wrong.
If you could tell me any other way it would really be a big help.You don't need any other way. Maybe you need to allow some time for the calling program to wind up. 20 seconds may be overkill, but I'm not in the mood to find how short it can be and still succeed.
The two classes are packaged in separate jars.import java.io.IOException;
public class Deletee {
    public static void main(String[] args) {
      try {
         String[] cmds = {"java", "-jar", "E:/temp/Deleter.jar"};
         Runtime.getRuntime().exec(cmds);
         System.exit(0);
      } catch (IOException ex) {
         ex.printStackTrace();
import java.io.File;
import javax.swing.JOptionPane;
public class Deleter {
   public static void main(String[] args) {
      File file = new File("E:/temp/Deletee.jar");
      try {
         Thread.sleep(20000);
      } catch (InterruptedException ex) {
         ex.printStackTrace();
      if (file.delete()) {
         JOptionPane.showMessageDialog(null, "Deleted");
      } else {
         JOptionPane.showMessageDialog(null, "Oops");
}Try it and see for yourself.
db

Is it possible to verify a signed jar-file from a program?

Is it possible to verify a signed jar-file from a program
(using some API) likewise jarsigner does?

Is it possible to verify a signed jar-file from a
program
(using some API) likewise jarsigner does?Hi,
You would have to open the jarfile, read each jar entry and for each of them do a getCertificates() and then in turn verify each certificate with the public key of the enclosed certificates in the jar file.
An easier solution would be to use the verify flag of the JarFile or JarInputStream.
Hope it helps..
Cheers,
Vijay

Signing Jars from within Java Code

Hi,
I would like to sign a jar file from within my Java code. Reason for this is that I wish to update a jar file at runtime, throw away the class loader that loaded the jar, and load the updated code inside a new classloader.
One problem, however: The jar file has to be signed before loading it. How can I do this from my Java program? Or do I need to have the jarsigner tool available at the location where I resign the jar?
Thanks in advance,
Ronald.

Hi,
In the meantime I found an answer to my problem. In rt.jar there exists a class sun.security.tools.JarSigner, which can be used for exactly this purpose. Not completely portable, but it'll do the trick.
Ronald.

Using a UNIX shell script to run a Java program (packaged in a JAR)

Hi,
I have an application (very small) that connects to our database. It needs to run in our UNIX environment so I've been working on a shell script to set the class path and call the JAR file. I'm not making a lot of progress on my own. I've attached the KSH (korn shell script) file code.
Thanks in advance to anyone who knows how to set the class path and / or call the JAR file.
loggedinuser="$(whoami)"
CFG_DIR="`dirname $0`"
EXIT_STATUS=${SUCCESS}
export PATH=/opt/java1.3/bin:$PATH
OLDDIR="`pwd`"
cd $PLCS_ROOT_DIR
java -classpath $
EXIT_STATUS=$?
cd $OLDDIR
echo $EXIT_STATUS
exit $EXIT_STATUS

Hi,
I have an application (very small) that connects to
our database. It needs to run in our UNIX environment
so I've been working on a shell script to set the
class path and call the JAR file.
#!/bin/sh
exec /your/path/to/java -cp your:class:paths:here -MoreJvmOptionsHere your.package.and.YourClass "$@"Store this is a file of any name, e.g. yuckiduck, and then change the persmissions to executechmod a+x yuckiduckThe exec makes sure the shell used to run the script does not hang around until that java program finishes. While this is only a minor thing, it is nevertheless infinite waste, because it does use some resources but the return on that investment is 0.
CFG_DIR="`dirname $0`"You would like to fetch the directory of the installation out of $0. This breaks as soon as someone makes a (soft) link in some other directory to this script and calls it by its soft linked name. Your best bet if you don't know a lot of script programming is to hardcode CFG_DIR.
OLDDIR="`pwd`"
cd $PLCS_ROOT_DIRVery bad technique in UNIX. UNIX supports the notion of a "current directory". If your user calls this program in a certain directory, you should assume that (s)he does this on purpose. Making your application dependent on a start in a certain directory ignores the very helpful concept of 'current directory' and is therefore a bug.
cd $OLDDIRThis has no effect at all because it only affects the next two lines of code and nothing else. These two lines, however, don't depend on the current directory. In particular this (as the cd above) does not change the current directory for the interactive shell your user is working in.
echo $EXIT_STATUS
exit $EXIT_STATUSEchoing the exit status is an interesting idea, but if you don't do this for a very specific purpose, I recommend not to do this for the simple reason that no other UNIX program does it.
Harald.

Is it possible to run a java program without using the command prompt?

Hi,
I was wondering whether it is possible to run a Java program (not an applet) without using a command line in the command prompt?
Basically I want to run a program that will be continually running in the background and hence I don't want to have a command prompt screen loaded up as well - I just want the program to be running in the task bar.
I know how to run the program in the task bar - but I still need to launch the program from the command prompt - is there anyway I can get a program running without having to start it from the command prompt?
Cheers

Or create a desktop shortcut (in Windows) or an application launcher ( in Linux GUI).

Problem with creation of a jar file from inside a java program

Hi,
I am trying to create a jar file at runtime from within a java program.
I am able to create a jar file just fine using:
String[] jarArgs = new String[3];
jarArgs[0] = "cvf";
jarArgs[1] = "C:\temp\myjar.jar";
jarArgs[2] = "C:\temp\this";
sun.tools.jar.Main main1 = new sun.tools.jar.Main(System.out, System.err, "jar");
main1.run(jarArgs);However, when I look at the jar it puts the absolute path to the files inside such as:
C:\temp\this\is\my\package\Class.class
instead of only this\is\my\package\Class.class
When running the jar command from the command line it works just fine and I have the relative paths in my jar file.
Does anyone have any experience with this and could help me out?
Thanks in advance
Edited by: mruf on Apr 11, 2008 1:51 AM

Shouldn't jarArgs[2] = "-C C:\temp\this"

Is it possible to run a jar file in another program???

Hello members,
i am sanketh. is it possible to run a jar file in another program.
if possible plz reply with an example or good links to go thru.

What do you mean "run a jar file in another program"? It's not very clear.

Is it possible to run the java program without main?

Hi,
Is it possible to run the java program without main?
if anybody know please tell me, how it is possible.
Regards,
Ramya

Hi,
Is it possible to run the java program without main?
if anybody know please tell me, how it is possible.
Regards,
RamyaWhy do you ask? It sounds like an odd question. Your program can be an applet and it doesn't need a main method in that case.
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Thanks for this answer . . .
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Is it possible to write a Java program to turn off the computer

Is it possible to write a Java program to turn off the computer

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Is JAR signing by Java program possible?

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