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JavaTM Archive (JAR) Files

Documentation Contents

JAR (Java Archive) is a platform-independent file format that aggregates many files into one. Multiple Java applets and their requisite components (.class files, images and sounds) can be bundled in a JAR file and subsequently downloaded to a browser in a single HTTP transaction, greatly improving the download speed. The JAR format also supports compression, which reduces the file size, further improving the download time. In addition, the applet author can digitally sign individual entries in a JAR file to authenticate their origin. It is fully extensible.

JAR File Specification and Overview

• JAR File Specification
• JAR File Overview

JAR Files and the Extensions Framework

• Extension Mechanism Architecture
  The mechanism for extending the Java platform uses the JAR file format to package extension classes. Manifest attributes are available to support the extension mechanism and related features such as package sealing and package versioning.

Jar Tool

• Jar tool reference page for Solaris
• Jar tool reference page for Windows

Reading and Writing JAR Files: API Specification

• Package java.util.jar: classes for creating and reading JAR files
• Class java.net.JarURLConnection: Abstract class for URL connections to JAR files using the jar protocol.

Tutorial

On the Java Software website:

• The Java Archive (JAR) File Format trail in the Java Tutorial.

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