load a folder from a jar

Question

I am trying to access a directory inside my jar file. I want to go through every of the files inside the directory itself. I tried using the following:

File[] files = new File("ressources").listFiles();
        for (File file : files) {
            XMLParser parser = new XMLParser(file.getAbsolutePath());
            // some work
        }

If I test this, it works well. But once I put the contents into the jar, it doesn't because of several reasons. If I use this code, the URL always points outside the jar.

structure of my project :

src 
   controllers
   models
         class that containt traitement
   views
ressources

score 1 · Answer 1 · edited May 23 '17 at 12:11

1

See this:

How do I list the files inside a JAR file?

Basically, you just use a ZipInputStream to find a list of files (a .jar is the same as a .zip)

Once you know the names of the files, you can use getClass().getResource(String path) to get the URL to the file.

edited May 23 '17 at 12:11

Community

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answered Dec 22 '13 at 01:58

k_g

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First i well create executable jar containt some ressources, my programm it work with IDE but jar no – Hassan Bendouj Dec 22 '13 at 02:03

score 0 · Answer 2 · answered Dec 22 '13 at 02:11

0

I presume this jar is on your classpath.

You can list all the files in a directory using the ClassLoader.

First you can get a list of the file names then you can get URLs from the ClassLoader for individual files:

public static void main(String[] args) throws Exception {
    final String base = "/path/to/folder/inside/jar";
    final List<URL> urls = new LinkedList<>();
    try (final Scanner s = new Scanner(MyClass.class.getResourceAsStream(base))) {
        while (s.hasNext()) {
            urls.add(MyClass.class.getResource(base + "/" + s.nextLine()));
        }
    }
    System.out.println(urls);
}

You can do whatever you want with the URL - either read and InputStream into memory or copy the InputStream into a File on your hard disc.

Note that this definitely works with the URLClassLoader which is the default, if you are using an applet or a custom ClassLoader then this approach may not work.

NB:

You have a typo - its resources not ressources.

You should use reverse domain name notation for your project, this is the convention.

answered Dec 22 '13 at 02:11

Boris the Spider

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I modify string base to my folder /ressources and i get this exception : Exception in thread "main" java.lang.NullPointerException at java.io.Reader.(Unknown Source) at java.io.InputStreamReader.(Unknown Source) at java.util.Scanner.(Unknown Source) – Hassan Bendouj Dec 22 '13 at 02:15
@ELMEKKIAnouar Have you checked your typos? And I assume you have used the correct `class` for the class reference. – Boris the Spider Dec 22 '13 at 02:17
i rename my folder to resources but i get always exception – Hassan Bendouj Dec 22 '13 at 02:18
Can you unpack your jar to ensure that the folder is in there? – Boris the Spider Dec 22 '13 at 02:19
i unpack jar i didt found resources i get all files directly in root – Hassan Bendouj Dec 22 '13 at 02:21
@ELMEKKIAnouar Well then your build process is broken not the code. – Boris the Spider Dec 22 '13 at 02:22
how can organized files in folder, files xml – Hassan Bendouj Dec 22 '13 at 02:23
@ELMEKKIAnouar You will have to post a question for that, describing your build process. – Boris the Spider Dec 22 '13 at 02:25
please i have more than 100 files XML i wanna to parse all files with some traitement my programm work with ide but not with jar executable. – Hassan Bendouj Dec 22 '13 at 02:27
I need to push all files in directory – Hassan Bendouj Dec 22 '13 at 02:27

load a folder from a jar

2 Answers2