Jar Files

1
Jar Files

• The Basics

2
Outline

• Create a Jar
• Viewing the Contents of a JAR File
• Extracting the Contents of a JAR File
• Modifying a Manifest File
• Running JAR-Packaged Software

3
Create a Jar

• The basic format of the jar command
• jar cf jar-file input-file(s)
• The c option says create a JAR.
• The f option says create it as a file.
• jar-file the files name.
• By convention, JAR filenames have a .jar
  extension.
• input-file(s) a space-separated file list to be
  archived.
• An input-file can contain the wildcard symbol.
• A directorys contents are added recursively.

4

• The generated JAR resides, compressed, in the
  current directory.
• It also generates a default manifest file.
• Some other options
• v Writes each added files name to stdout.
• 0 (zero) Dont compress the JAR file.

5
Example

• The TicTacToe applet demo comprises
• a class file
• audio directory contain sound files
• images directory contain GIF images
• all in a directory called TicTacToe

6

• In the TicTacToe directory, execute
• jar cvf TicTacToe.jar TicTacToe.class audio
  images
• TicTacToe.jar is placed in the current directory.
• The verbose output appears on the next slide.

7

• adding TicTacToe.class (in3825) (out2222)
  (deflated 41)
• adding audio/ (in0) (out0) (stored 0)
• adding audio/beep.au (in4032) (out3572)
  (deflated 11)
• adding audio/ding.au (in2566) (out2055)
  (deflated 19)
• adding audio/return.au (in6558) (out4401)
  (deflated 32)
• adding audio/yahoo1.au (in7834) (out6985)
  (deflated 10)
• adding audio/yahoo2.au (in7463) (out4607)
  (deflated 38)
• adding images/ (in0) (out0) (stored 0)
• adding images/cross.gif (in157) (out160)
  (deflated -1)
• adding images/not.gif (in158) (out161)
  (deflated -1)

8
Using the Wildcard Character

• Using the wildcard character (), an equivalent
  command, in this case, is
• jar cvf TicTacToe.jar

9
Outline

• Create a Jar
• Viewing the Contents of a JAR File
• Extracting the Contents of a JAR File
• Modifying a Manifest File
• Running JAR-Packaged Software

10
Viewing the Contents of a JAR File

• To view a jar, execute
• jar tf jar-file
• The t option view the JARs table of contents.
• Example (continued)
• jar tf TicTacToe.jar
• This commands output appears on the next slide.

11

• META-INF/MANIFEST.MF
• TicTacToe.class
• audio/
• audio/beep.au
• audio/ding.au
• audio/return.au
• audio/yahoo1.au
• audio/yahoo2.au
• images/
• images/cross.gif
• images/not.gif

12
jar tvf TicTacToe.jar displays

• 256 Mon Apr 20 105028 PDT 1998
  META-INF/MANIFEST.MF
• 3885 Mon Apr 20 104950 PDT 1998 TicTacToe.class
  
• 0 Wed Apr 15 163932 PDT 1998 audio/
• 4032 Wed Apr 15 163932 PDT 1998 audio/beep.au
• 2566 Wed Apr 15 163932 PDT 1998 audio/ding.au
• 6558 Wed Apr 15 163932 PDT 1998 audio/return.au
  
• 7834 Wed Apr 15 163932 PDT 1998 audio/yahoo1.au
  
• 7463 Wed Apr 15 163932 PDT 1998 audio/yahoo2.au
  
• 0 Wed Apr 15 163944 PDT 1998 images/
• 157 Wed Apr 15 163944 PDT 1998
  images/cross.gif
• 158 Wed Apr 15 163944 PDT 1998 images/not.gif

13
Outline

• Create a Jar
• Viewing the Contents of a JAR File
• Extracting the Contents of a JAR File
• Modifying a Manifest File
• Running JAR-Packaged Software

14
Extracting a JARs Contents

• To extract the contents of a JAR, execute
• jar xf jar-file
• The x option extract files from jar-file.
• This overwrites existing files having the same
  pathname as the extracted files.
• Example (continued)
• jar xf TicTacToe.jar
• Extracts the JARs files into the current
  directory.

15
Outline

• Create a Jar
• Viewing the Contents of a JAR File
• Extracting the Contents of a JAR File
• Modifying a Manifest File
• Running JAR-Packaged Software

16
Modifying a Manifest File

• To create a JAR add manifest info
• jar cmf manifest-addition jar-file input-file(s)
• The m option merge a manifest file into the
  JARs.
• manifest-addition the manifest files name.
• To designate the main class in the JAR, the
  manifest-addition file contains the line
• Main-Class classname
• where classname must omit the .class extension
• E.g., TicTacToe (not TicTacToe.class)

17
Outline

• Create a Jar
• Viewing the Contents of a JAR File
• Extracting the Contents of a JAR File
• Modifying a Manifest File
• Running JAR-Packaged Software

18
Running JAR-Packaged Software

• Applets Packaged in JAR Files
• ltapplet codeTicTacToe.class archive"TicTacToe.ja
  r"
• width120 height120gt
• lt/appletgt
• The archive parameter specifies the relative path
  to the JAR file.
• This example assumes that the JAR HTML files
  are in the same directory.

19

• JAR Files as Applications - 1.2 platform
• java -jar jar-file
• The JARs manifest must designate the main-class.
• Example (continued)
• java -jar TicTacToe.jar
• Based on the TicTacToe.jar with the manifest that
  designates TicTacToe as the main-class.