在jar文件夹中创建文件

Question

I have a jar file abc.jar
which has some certain code to create a file inside a folder named temp of same jar file.
like

createFile()

Now i want to include abc.jar into my other web project. Which should call this function createFile() and create file accordingly.
So is there any way to create file inside jar file.
I'm aware about jar which is always be compressed and read only.
But still is there a work around for the same, will be great help for me.
:)

Answer 1

For reading a file that is in abc.jar , you can use ClassLoader.getResource() , but I don't think Java provides a similar facility for adding a file to a jar (for security purposes).

A jar file is simply a zip file, so if you really needed to, you could un-zip it to a temporary directory, add the file, and then re-create the jar with your new file in it. However, I think this would not achieve the effect you're looking for - whatever file you added to the jar file in this manner would not be available to your running code, because the original jar (without the added file) was already loaded.

Answer 2

You could extract the complete Jar, add the file to the extracted directory structure and recreate the jar out of the directory structure.

You can use ZipInputStream and ZipOutputStream for example to achieve this goal. Furthermore classes related to ZipFile and ZipEntry can be of help.

Directly adding a file is not possible as far as I know.

Answer 3

Take a look at TrueVFS: http://truevfs.net/ (or its predecessor TrueZip https://christian-schlichtherle.bitbucket.io/truezip/ ). It provides a virtual file system access to archive files.