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Objectives: 1. Archiving and Packaging Java Code 2. The jar Program 3. Example Applet PowerPoint Presentation
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Objectives: 1. Archiving and Packaging Java Code 2. The jar Program 3. Example Applet. JAR Files. JAR file archives provide packaging for applications, applets, & JavaBeans Multiple classes can be packaged in JAR files JAR Files specified within HTML Manifest file

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slide1
Objectives: 1. Archiving and Packaging Java Code

2. The jar Program

3. Example Applet

JAR Files

jar files
JAR file archives provide packaging for applications, applets, & JavaBeans

Multiple classes can be packaged in JAR files

JAR Files specified within HTML

Manifest file

JAR files use ZIP compression format

JAR Files
jar files1
provide a delivery mechanism for JavaBeans, packaging all the necessary resources together in a single file. Multiple Beans may be contained in a single JAR file, and the file may also contain an optional manifest which lists the contents.

help transport Beans over the Internet in easy-to-manage packages, and they are also used to archive applets for more efficient downloading performance.

JAR Files:
the jar utility
Creates JAR files

Adds to existing archives

Extracts items in an archive

Lists archive contents

Syntax:

jar {ctux} [vfm0M] [jar-file] [manifest-file] files

The jar Utility
jar command jar ctux vfm0m jar file manifest file files
jar-file specifies the name of the archive file. No required naming conventions exist for Java archive files, although you will most likely see the file extension .jar associated with them.

The manifest-file argument is a file containing a list of the jar file contents. A manifest file is required when using the m command line option.

More...

jar Commandjar {ctux} [vfm0M] [jar-file] [manifest-file] files
jar command jar ctux vfm0m jar file manifest file files1
files to be archived are listed at the end of the command and are separated by whitespace.

Wildcard characters are accepted

directory names are followed recursively, i.e., all files in subdirectories will also be archived.

File names are relative to the directory from which you run the jar command

special –C option introduced in Java 1.2 to change the relative directory.

forward or backward slashes are accepted, making the jar command operating-system independent.

jar Commandjar {ctux} [vfm0M] [jar-file] [manifest-file] files
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

jar command line options
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

Examples of jar command
jar files html
Improve Applet download performance

compression of JAR files allows efficient downloading of applets over the Web.

entire archive may be downloaded in a single HTTP transaction.

avoids reconnect each time a specific .class file or resource is needed.

ARCHIVE Tag

<APPLET ARCHIVE=“Simulator.jar” CODE=Stock.class WIDTH=350 HEIGHT=250>

</APPLET>

filename is relative to the location of the HTML page.

still need a CODE tag to indicate which class within the archive starts the applet.

JAR Files & HTML
the manifest
The manifest file exists to provide information about the contents of its associated jar file.

Automatically created

if not specified otherwise, named manifest.mf

placed in the archive under a directory called /META-INF

M option in jar command suppresses creation.

Lists the entries in the archive

First entry identifies manifest version Example:

Manifest-Version: 1.0

Created-By: 1.5.0 (Sun Microsystems Inc.)

applies to the entire JAR file

The Manifest
manifest contents
Subsequent sections must begin with

Name: <entry>

describe individual elements JavaBeans, files, packages, and URLs.

Each section of the manifest file refers to an entry in the archive and is separated by a blank line.

Attribute-value pairs of the format attribute: value are used in each section to give information about that particular entry.

Name: Calculator.class

lines describing this file

Name: edu/weber/mypkg

lines describing this package

Manifest Contents
manifest contents1
Attribute/Value pairs

Note Java-Bean attribute in example:

Name: StockBroker/Simulator/Stock.class

Digest-Algorithms: MD5 SHA

MD5-Digest: wuXrtYN-56Nn4rtDFewq=-tr

SHA-Digest: fg67tKdkfR65-SRkdrslegvY-tyK

Java-Bean: True

Manifest Contents
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

Custom Manifest File Indicating Beans
creating the archive file
create an archive file with a customized manifest file by using both the m and foptions and giving the required arguments as shown in the slide. The generated manifest.mf file in the archive should have the information given in Simulator.mf (which you write).

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

if the jar options contain both the letters f and m, the JAR and manifest files listed in the command line should be in the same order. For example, if f comes before m, the JAR filename should come before the manifest filename.

Creating the Archive File
examples
See Composites using a jar in the Mastermind Directory

See Animation Demo using a jar at:

http://acad.kutztown.edu/~spiegel/cis421/Animation/AppletJAR/ball.htm

inner classes specified in a manifest

Examples