I have a jar file which is used in html file as applet. I want to modify the content of the jar file and to rebuild the jar file so that the html will work fine with the new jar file. How can i do this??
I already tried unzipping using 7zip nad modified the source and created the new jar. But when i use it in html it shows some java.lang.Classnotfound error
You can unjar or rejar the classes and source files as you wish.
unjar
jar -xvf abc.jar
jar
jar cf abc.jar input-files
http://docs.oracle.com/javase/tutorial/deployment/jar/build.html
Make the changes in the code (.java files), recompile to get the .class files. Then simply replace the old .class files in the jar with the new ones. I usually use WinZip, but you can use whatever app that can handle .Zip files. It should just work.
I've faced cases where the launcher of the app uses some sort of verification and checks for this kind of changes. I had to use a new launch script. This doesn't seem to be your case though.
This is surely possible from the command line. Use the u option for jar
From the Java Tutorials:
jar uf jar-file input-file(s)
"Any files already in the archive having the same pathname as a file being added will be overwritten."
See Updating a JAR File
A brief test shows this quickly updates changes apart from trying to delete the file.
I haven't seen this answer on other threads about modifying jar files, and many, marked as duplicates, suggest there is no alternative but to remake the jar completely. Please correct if wrong.
JARs are just ZIP files, use whatever utility you like and edit away!
Disclaimer: When reverse engineering any code be sure that you are staying within the limits of the law and adhering to the license of that code.
Follow the instructions above to unpack the JAR.
Find the original source of the JAR (perhaps its on SourceForge) and download the source, modify the source, and rebuild your own JAR.
You can also decompile the class files in the JAR. This is a rather advanced process and has a lot of "gotchas".
Related
I have a huge JAR file, which I created with Maven Shade plugin.
I run this with java -jar foo.jar , and my UI opens. Now I want to execute *.exe file, which is also in that JAR file, how can I do this?
I tried putting the exe to my classpath and run it from there, but after trying I found out that classpath is actually the location, where my JAR is.
Any suggestions?
Found this thing here, but is this really the best solution? Seems like alot of work, I think I have different case here, because I can define the location of exe myself and the JAR is created by me.
run exe which is packaged inside jar
Why I need this?
I want to give user a single file executable, which he can run, but my program is using the *.exe. Should I put the exe next to my jar and there will be 2 files or there is solution for my requirements?
Copying the file to a temporary location and running it is the way to go. The answer you linked to does much more work that necessary, as you can get your exe file as an InputStream and copy it to a file with a utility like Apache Commons IO FileUtils.copy(in, out)
See How do I copy a text file from a jar into a file outside of the jar? for example.
It's not about the location, it's about the fact that you need to tell your OS to run the exe and, unfortunately, you can't do that by providing a location within a jar.
Is it possible to take existing .class files and a MANIFEST.MF to create a jar file?
Is there a library that can create a "valid" jar-file? I tried it manually and it didn't work (using 7zip).
ERROR: "Invalid or corrupt jar file"
If everything has been compiled before, it should (in my understanding) theoretically work, if you create a new zip file, put all the files in it in the original structure and then rename it to "jar".
My idea is to program something like this with java code. A solution where I could add a file to an existing jar, would also be ok.
If you're interested in why I want to use this, look at my initial question: Compile javacode out of a running java accpilaction - on a system that hasn't JDK installed
Well Jar -cf
Try the jar command in $JAVA_HOME/bin
$JAVA_HOME is the path to you JRE/JDK installation
Is there any chance, to recreate a (netbeans-)project from a .jar file?
Becuase I trusted some silly cryption-software that corrupt's my file.
Is their any suggestion or solution?
I already extracted the .jar file with terminal commands 'jar xf MyJarFile.jar'.
But I can't read the code in it...
You could decompile the jar into the sources and then create a new project and drag all the sources into your src folder. I like using JD-GUI for decompiling .jars: http://java.decompiler.free.fr/?q=jdgui
I also recommend using JD-GUI, it helped me a lot when my simple text editor corrupted my .java files and I was able to convert the classes back into source using it.
delete the $ files first, then Jad is the best, jdgui makes errors.
I am using eclipse IDE and want to edit the attached source file of the jar file. For doing this i downloaded the src.zip and attached the file, but it is opening as a .class though I am able to read the file (which is a .class file) but i also want to edit the file.
Why I am not allowed to edit it? how to open an attached file with .java extension not .class extension.
thanks in advance
That's not possible. In order to edit the source, you have to unpack the JAR and create an eclipse project, from which you can then create a JAR with the modified code.
Because you have to link it... Source files are not tied to compiled classes in jar, so if you edit it, nothing will happen to the jar file
You have to create a separate project in Eclipse, and rebuild the jar with your modifications
.class files are not readable by human being unless you decompile it. Many decompilers exist. Carefull about what you are allowed to do and what you aren't, though...
Usually, .java aren't in .jar.
Is there a way to extract the source code from an executable .jar file (Java ME)?
Use JD GUI. Open the application, drag and drop your JAR file into it.
You can extract a jar file with the command :
jar xf filename.jar
References : Oracle's JAR documentation
I believe this can be done very easily. You can always extract the source files (Java files) of a jar file into a zip.
Steps to get sources of a jar file as a zip :
Download JAD from http://techieme.in/resources-needed/ and save it at any
location on your system.
Drag and drop the jar for which you want the sources on the JAD.
3 JAD UI will open with all the package structure in a tree format.
Click on File menu and select save jar sources.
It will save the sources as a zip with the same name as the jar.
Hope this helps.
The link is dead due to some reason so adding the link from where you can download the JDGUI
Your JAR may contain source and javadoc, in which case you can simply use jar xf my.jar to extract them.
Otherwise you can use a decompiler as mentioned in adarshr's answer:
Use JD GUI. Open the application, drag
and drop your JAR file into it.
I know it's an old question Still thought it would help someone
1) Go to your jar file's folder.
2) change it's extension to .zip.
3) You are good to go and can easily extract it by just double clicking it.
Note: I tested this in MAC, it works. Hopefully it will work on windows too.
Do the following on your linux box where java works (if u like the terminal way of doing things)
cd ~
mkdir decompiled_code && cd decompiled_code
// download jar procyon from https://drive.google.com/file/d/1yC2gJhmLoyE8royCph5dLEncgkNZXj58/view?usp=sharing
java -jar procyon-decompiler-0.5.36.jar /Path/to/your/jar -o .
NOTE : as #Richard commented "this may be illegal depending on whether you own the copyright to the jar, the country you live in and your purpose for doing it."
Steps to get sources of a jar file as a zip :
Download JD-GUI from http://java-decompiler.github.io/ and save it
at any location on your system.
Drag and drop the jar or open .jar file for which you want the
sources on the JD.
Java Decompiler will open with all the package structure in a tree
format.
Click on File menu and select save jar sources. It will save
the sources as a zip with the same name as the jar.
Example:-
We can use Eclipse IDE for Java EE Developers as well for update/extract code if require.
From eclipse chose Import Jar and then select jar which you need. Follow instruction as per image below
AndroChef Java Decompiler produces very good code that you can use directly in your projects...
Above tools extract the jar. Also there are certain other tools and commands to extract the jar.
But AFAIK you cant get the java code in case code has been obfuscated.
suppose your JAR file is in C:\Documents and Settings\mmeher\Desktop\jar and the JAR file name is xx.jar, then write the below two commands in command prompt:
1> cd C:\Documents and Settings\mmeher\Desktop\jar
2> jar xf xx.jar
-Covert .jar file to .zip (In windows just change the extension)
-Unzip the .zip folder
-You will get complete .java files