How to read a file in another jar file?

Question

I am running a GUI application (A.jar). Then I add a plugin (B.jar) to this GUI(A.jar). Now I want to access the manifest.mf file in B.jar. I tried B.class.getResourceAsInputStream("/META-INF/MANIFEST.MF"). However, what I got is the manifest.mf in A.jar, not in B.jar.

Anyone can give me some hints on this problem? Thanks so much.

Answer 1

It is the case that the general class loader will take the path the comes first on the class path, and evidently A.jar comes first, before B.jar.

String someUniqueResourceInBJar = "...";
URL url = B.class.getResource(someUniqueResourceInBJar);
url = new URL(url.getPath().replaceFirst(someUniqueResourceInBJar + "$", "")
    + "META-INF/MANIFEST.MF";
url.openStream();

The url will be something like "jar:file://.../B.jar!META-INF/MANIFEST.MF".

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Alternatively getting the class URL:

URL url = b.class.getProtectionDomain().getCodeSource().getLocation();