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5 Replies Latest reply: Oct 23, 2012 8:18 PM by EJP RSS

Why are all jar files not compressed in the JRE installer?

969947 Newbie
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I used 7zip to unpack jre-6u12-windows-i586-p.exe (Oracle JRE Installer). On unpacking, I got a core.zip, a zipper.exe and a few other files.

Again on exploding core.zip I found a few things. core.zip contains all the jar files just like it would be after installation except for 7 jar files.

charsets.jar
deploy.jar
javaws.jar
jsse.jar
localedata.jar
plugin.jar
rt.jar

Instead of these jar files there exists the corresponding packfiles

charsets.pack
deploy.pack
javaws.pack
jsse.pack
localedata.pack
plugin.pack
rt.pack

I think these are files created by pack200.exe & unpack200.exe is run on them after installation to create the corresponding jar files.

So now I have a few questions

Why are only these 7 files run through pack200.exe. I assume its because they are bigger than other files. But it wouldn't take that much effort to pack all jar files & unpack them after installation.

The .pack extension suggests that these are packed but not gzipped. Again why would Oracle not do a gzip also? for eg with rt.jar packing reduces size from 45 MB to 12 MB, while adding gzip also reduces it to 6 MB.

Edited by: 966944 on Oct 22, 2012 8:19 AM

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