Question

Im using the following Code to try an package a directory with all its subdirectories and files into one jar-file.

private void writeFile(JarOutputStream jos, File f) throws IOException {
  byte buffer[] = new byte[BUFFER_SIZE];

  if (f == null || !f.exists())
      return; //

  JarEntry jarAdd = new JarEntry(f.getName());
  jarAdd.setTime(f.lastModified());
  jos.putNextEntry(jarAdd);

  if(f.isDirectory()){
      File[] files = f.listFiles();
      for(int i = 0; i < files.length ; i++){
          writeFile(jos,files[i]);
      }
  }
  else{
      FileInputStream in = new FileInputStream(f);
      while (true) {
        int nRead = in.read(buffer, 0, buffer.length);
        if (nRead <= 0)
          break;
        jos.write(buffer, 0, nRead);
      }
      in.close();
  }
}

However FileInputStream does not work on directories, so i assume adding the JarEntry will suffice.

Since I do have another problem, I am not able to see if this assumption is correct.
This problem is that many entries made are duplicate.

When trying to add the structure…

activation
/--activation
   /-- somefile.txt

…this code fails, because activation is added twice to the jar.
Since those are different directories nested within each other I do not see why this should not work in some way.

It seems that adding the entry using file.getName() will get entry-ids that do not
differentiate between the directories those files are in.
However when I use

file.getAbsolutePath() 

for example, the jar structure is messed up with
directories like “C_” and the contained files are not readable anymore.

Can anyone recommend a way to package directory structures in a jar file correctly?

Answer 1

Note that a JarEntry representing a directory (folder) must end with a slash (“/“) in order to be treated as such; otherwise it will be considered a plain file.

JarEntry dir = new JarEntry("activation/");