Question

I’m trying to have my application load a resource (binary file) transparently:

If the file exists under the current directory, open it.
If not, try looking in the current JAR file if applicable.
If not, try looking in other JAR files. (This is optional and I don’t mind explicitly specifying which JAR files.)

So far I know of File which opens a local file and ClassLoader which has getResource* for JAR contents.

Is there a class which combines the two? If not, how should I go about writing it myself? Should I write a ClassLoader which also checks the local filesystem? Using File? (I’m very unfamiliar with Java and don’t even know what’s a good type to return. InputStream?)

Thanks

P.S. By “file” I mean “path”, e.g. “data/texture1.png”.

Answer 1

Doing #1 and #3 is pretty easy. Doing #2 (just looking in the current JAR only) is much harder as it requires you figuring out what JAR you

If you wanted to check the filesystem first, otherwise load from classpath, it would be something like:

public java.io.InputStream loadByName(String name) {
  java.io.File f = new java.io.File(name);
  if (f.isFile()) {
    return new FileInputStream(f);
  } else {
    return getClass().getResource(name);
  }
}

If you want to prefer loading from the same JAR file first, you will need to figure out where it is. Check out Determine which JAR file a class is from for more info on figuring out the JAR file you want to load the resource from.