Java Projects - Second Edition

Packaging classes into a JAR file

When you deliver a Java application, usually the code is packaged into JAR, WAR, EAR, or some other packaged format. We learn something again that seems to be obscure at first sight, but in reality, this is not that complex. They are all ZIP files. You can open any of these files using WinZip or some other ZIP manager that you have a license for. The extra requirement is that, for example, in the case of a JAR file, the archive should contain a directory named META-INF and inside it a file named MANIFEST.MF. This file is a text file and contains meta information in the format, which is as follows:

Manifest-Version: 1.0 
Created-By: 11-ea (Oracle Corporation)

There can be a lot of other information in the file, ...