Objectives:1. Archiving and Packaging Java Code

1
JAR Files

• Objectives 1. Archiving and Packaging Java Code
• 2. The jar Program

2
JAR Files

• JAR file archives provide packaging for
  Application, Applets, JavaBeans
• Multiple classes can be packaged in JAR files
• JAR Files with HTML
• Manifest file
• JAR files use ZIP compression format

3
The jar Program

• Creates JAR files
• Extracts Contained Elements
• Lists JAR file contents
• Usage
• jar ctux vfm0M jar-file manifest-file
  files

4
jar command line options

• Only one of the following
• c Create a new archive file
• t List the table of contents for the archive
  file
• u Update the contents of the archive or manifest
• x Extract named files (or all) from the archive
• Other options can be combined or omitted
• v Verbose output
• f Specify jar-file
• m Include information from manifest-file
• 0 Do not use compression
• M Do not create a manifest file for the archive
  entries

5
Examples of jar command

• Create an archive called Simulator.jar that
  contained the single class Machine.class
• jar cf Simulator.jar Machine.class
• List the table of contents of Simulator.jar
  using verbose output
• jar tvf Simulator.jar
• Extract all contents of Simulator.jar
• jar xvf Simulator.jar

6
JAR Files HTML

• Improve Applet download performance
• ARCHIVE Tag
• ltAPPLET ARCHIVESimulator.jar CODEStock.class
  WIDTH350 HEIGHT250gt
• lt/APPLETgt

7
The Manifest

• Automatically created
• Named /META-INF/Manifest.mf
• Lists the entries in the archive
• First entry identifies manifest version
• Manifest-Version 1.0
• Created-By 1.5.0 (Sun Microsystems Inc.)

8
Manifest Contents

• Main section shown in previous slide
• Applies to the entire JAR file
• Subsequent sections must begin with Name entry
  and describe individual elements contained in JAR
  file like JavaBeans, files, packages, and URLs.
• Name Calculator.class
• lines describing this file
• Name edu/weber/mypkg
• lines describing this package

9
Manifest Contents

• Attribute/Value pairs
• Note Java-Bean attribute
• Name StockBroker/Simulator/Stock.class
• Digest-Algorithms MD5 SHA
• MD5-Digest wuXrtYN-56Nn4rtDFewq-tr
• SHA-Digest fg67tKdkfR65-SRkdrslegvY-tyK
• Java-Bean True

10
Custom Manifest File Indicating Beans

• Manifest-Version 1.0
• Name StockBroker/Simulator/Stock.class
• Java-Bean True
• Name StockBroker/Simulator/Helper.class
• Java-Bean False
• Name StockBroker/Simulator/Price.class
• Java-Bean True

11
Creating the Archive File

• jar cfm Simulator.jar Simulator.mf
  StockBroker/Simulator/Stock.class
  StockBroker/Simulator/Helper.class
  StockBroker/Simulator/Price.class