Reading .cer files from jar file failing

Question

I was trying to install client SSl cert at runtime. The certs are already packed with jar and is available in the below location

While trying to read all available .cer

Answer 1

As Luke indicates in comment, Java File only handles 'real' files (and directories) on the OS filesystem, which in Java 7 up with "new I/O" (NIO) is called the 'default' filesystem, but we can now have other Java-defined filesystems including one that does work on entries in a jar/zip:

    String name = ...;
    URI uri = (myclass/loader).getResource(name).toURI(); 
    // I think Paths.get using ZipFileSystemProvider ought to handle the whole URI but it doesn't, so:
    String[] spec = uri.getSchemeSpecificPart().split("!/");
    if( ! uri.getScheme().equals("jar") || spec.length != 2 || ! spec[0].startsWith("file:") ) throw new Exception ("bad URI for jar resource");
    FileSystem fs = FileSystems.newFileSystem(new URI("jar",spec[0],null), new HashMap());
    Files.list(fs.getPath(spec[1])) .forEach(p -> System.out.println(p.toString()));
    // instead of System.out.println can do something else, or instead of .forEach .collect into a variable
    fs.close(); // or use try-resources to close automatically