What is a JAR file ?

• This is Java’s version of a UNIX tar file and contains a variety of files including .class, image, sound, HTML pages

• The JAR file is stored in compressed (zip) fashion and can also be signed using standard digital signature techniques.

  • Perhaps they download faster due to compression!

• There is a “control” file called a manifest which inter alia is used to identify any JavaBean present. It also specifies message digest algorithm

• JavaBeans must be stored in JAR files and must be identified in manifest

• JAR files can be accessed from HTML using <APPLET> tag

  • <APPLET ARCHIVES=“first.jar,second.jar” CODE=“yourclass.class” WIDTH=100 HEIGHT=200 ></APPLET>

Java looks first in .jar files for requested class

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