Java Cryptography

Creating

Let’s use jar to archive the files that make up the GraphLayout example applet that comes with the JDK 1.1. First, let’s look at the files in that directory:

C:\ dir

 Volume in drive C is BUENDIA
 Volume Serial Number is 1929-10EE
 Directory of C:\jdk1.2beta2\demo\GraphLayout

.              <DIR>        04-16-97  8:28a .
..             <DIR>        04-16-97  8:28a ..
EDGE~1   CLA           316  09-18-96 12:16p Edge.class
GRAPH~1  CLA         3,059  09-18-96 12:16p Graph.class
GRAPH~1  JAV         9,503  12-06-96 10:14a Graph.java
GRAPHP~2 CLA         5,986  09-18-96 12:16p GraphPanel.class
NODE~1   CLA           375  09-18-96 12:16p Node.class
EXAMPL~1 HTM           415  09-18-96 12:16p example1.html
EXAMPL~2 HTM           241  09-18-96 12:16p example2.html
EXAMPL~3 HTM           619  09-18-96 12:16p example3.html
EXAMPL~4 HTM           283  09-18-96 12:16p example4.html
AUDIO          <DIR>        04-16-97  8:28a audio
         9 file(s)         20,797 bytes
         3 dir(s)     222,429,184 bytes free

All the applet needs to run are the .class files and the sound files contained in the audio directory.

You can create a JAR using the -c option. By default, jar sends data to standard output. For most commands, though, you can use the -f option to specify a destination file. In this case, we want to specify the name of the destination JAR as well as the files to put into it, so we combine the -c and -f options:

C:\ jar -cf GraphLayout.jar *.class audio

This operation is completed in stony silence. If that makes you nervous, you can get some more feedback by adding the -v option (verbose). Like -f, the -v option can be combined with most of jar’s other options: ...