How to retrieve all files contained in a folder inside a JAR?

Question

I need to get a folder within a jar file.

The folder is name postman and contains some JSON files. My purpose is to get that folder as a File object, list the files to do some actions on names and parse the content for some other actions.

The problem I got is that I can't get that folder and his content.

After reading some documentation and topics from here, I tried many things, increase my understanding about that kind of stuff.

Now I got this :

URL url = SasPostman.class.getClassLoader().getResource(POSTMAN_RESOURCES_PATH);
// url output -> jar:file:/home/randomFolder/myJarFile.jar!/postman

try {
     JarURLConnection connection = (JarURLConnection) url.openConnection();
     File myFolder = new File(connection.getJarFileURL().toURI());
     if(myFolder.exists() && myFolder.isDirectory()) {
       // some code
     }

MyFolder exist but isn't a directory. I added some log to try to understand each steps, but I am not able to draw conclusion from it.

connection.getURL() results to jar:file:/home/randomFolder/myJarFile.jar!/postman

connection.getURL().toURI() results to jar:file:/home/randomFolder/myJarFile.jar!/postman

connection.getJarFileURL().toURI() results to jar:file:/home/randomFolder/myJarFile.jar

Even if I use the paths endind with the folder name, myFolder isn't the expected directory.

I probably miss something or maybe it should be done in another way. Maybe by coying the whole folder I need into another location ? I don't know..

I also looked at some documentation of using ZipFile but I just see how to use it to retrieve one file. Or I need to get all the files from my folder.

Any help would be appreciated !

Answer 1

You could try this and adapt it as necessary:

import java.util.Map;
import java.util.HashMap;
import java.net.URI;
import java.nio.file.Path;
import java.nio.file.DirectoryStream;
import java.nio.file.Files;
import java.nio.file.FileSystem;
import java.nio.file.FileSystems;

public class ZipFSPUser {
    public static void main(String[] args) throws Throwable {
        Map<String, String> env = new HashMap<>();
        env.put("create", "true");
        // locate file system by using the syntax
        // defined in java.net.JarURLConnection
        URI uri = URI.create("jar:file:///tmp/zipfstest.zip");

        try (FileSystem zipfs = FileSystems.newFileSystem(uri, env)) {
            Path jsonDir = zipfs.getPath("/root/a");
            try (DirectoryStream<Path> paths = Files.newDirectoryStream(jsonDir, "*.json")) {
                paths.forEach(System.out::println);
            }
        }
    }
}