RFR - 8132734: java.util.jar.* changes to support multi-release jar files

[Wang Weijun]

> On Oct 21, 2015, at 3:17 PM, Xueming Shen <xueming.shen at oracle.com> wrote:
> 
> We might want to bring in Max to take a look if what I said is really a supported use scenario.

I haven't read Steve's latest code change. I will read if you think it's necessary.

First, I think we agree that the multi-release jar file feature is only making use of the existing jar file format and does not intend to introduce any change to its specification. This means a JarFile signed by one JDK release should be verified by another JDK release.

Ok, the next question is, should it modify the JarFile API? I hope not, because the JarFile API is the single entry we access a JarFile when we want to sign or verify it. I hope there is a brand new API for a multi-versioned jar file, probably a child class of JarFile, so that no matter you call getJarEntry() or entries() on it, you always get the versioned one and the unrelated ones are completely invisible.

If this is not OK, maybe we can rename the current JarFile to RawJarFile and name the new API JarFile. Signing and verification will work on RawJarFile.

Not sure if it's easy.

--Max