SpringBoot read the file MANIFEST.MF in BOOT-INF/ lib, but an exception occurred

I tried to read the file MANIFEST.MF in BOOT-INF/ lib, but an exception occurred

Caused by: java.lang.IllegalStateException: Unable to determine code source archive from file:/Users/bruce/disk/IdeaProjects/grpc_integration/grpc_provider/target/grpc_provider-0.0.1.jar!/BOOT-INF/lib/netty-common-4.1.73.Final.jar!
        at com.bruce.provider.util.ManifestUtil.createArchive(ManifestUtil.java:27)
        at com.bruce.provider.ProviderApplication.main(ProviderApplication.java:56)
        ... 8 more

Here is my code:

public class ManifestUtil {

    public static Archive createArchive(Class<?> clazz) throws Exception {
        ProtectionDomain protectionDomain = clazz.getProtectionDomain();
        CodeSource codeSource = protectionDomain.getCodeSource();
        URI location = (codeSource != null) ? codeSource.getLocation().toURI() : null;
        String path = (location != null) ? location.getSchemeSpecificPart() : null;
        if (path == null) {
            throw new IllegalStateException("Unable to determine code source archive");
        }
        File root = new File(path);
        if (!root.exists()) {
            throw new IllegalStateException("Unable to determine code source archive from " + root);
        }
        return (root.isDirectory() ? new ExplodedArchive(root) : new JarFileArchive(root));
    }
}

@SpringBootApplication
public class ProviderApplication {

    public static void main(String[] args) throws Exception {

        SpringApplication.run(ProviderApplication.class, args);

        Archive archive2 = ManifestUtil.createArchive(ByteProcessor.class);
        System.out.println(archive2.getManifest().getMainAttributes());

    }

}

Comment From: wilkinsona

You appear to be trying to treat a nested jar as if it's directly available on the file system. That's the main reason why your code is failing. Rather than using the Archive API, I'd recommend getting a URLConnection by calling openConnection() on the location of the CodeSource. You can then cast that to JarURLConnection and call getManifest().

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