Question

I know we can do something like this:

Class.class.getResourceAsStream("/com/youcompany/yourapp/module/someresource.conf")

to read the files that are packaged within our jar file.

I have googled it a lot and I am surely not using the proper terms; what I want to do is to list the available resources, something like this:

Class.class.listResources("/com/yourcompany/yourapp")

That should return a list of resources that are inside the package com.yourcompany.yourapp.*

Is that possible? Any ideas on how to do it in case it can’t be done as easily as I showed?

Note: I know it is possible to know where your jar is and then open it and inspect its contents to achieve it. But, I can’t do it in the environment I am working in now.

Answer 1

For resources in a JAR file, something like this works:

URL url = MyClass.class.getResource("MyClass.class");
String scheme = url.getProtocol();
if (!"jar".equals(scheme))
  throw new IllegalArgumentException("Unsupported scheme: " + scheme);
JarURLConnection con = (JarURLConnection) url.openConnection();
JarFile archive = con.getJarFile();
/* Search for the entries you care about. */
Enumeration<JarEntry> entries = archive.entries();
while (entries.hasMoreElements()) {
  JarEntry entry = entries.nextElement();
  if (entry.getName().startsWith("com/y/app/")) {
    ...
  }
}

You can do the same thing with resources “exploded” on the file system, or in many other repositories, but it’s not quite as easy. You need specific code for each URL scheme you want to support.