2.3 Installing Jython
To install Jython, you need a Java Virtual
Machine (JVM) that complies with Java 1.1 or higher. See http://www.jython.org/platform.html for
advice on JVMs for your platform.
To download Jython, visit http://www.jython.org and follow the link
labeled Download. The latest version at the time of this writing is:
- http://prdownloads.sf.net/jython/jython-21.class
In the following section, for clarity, I assume you have created a
new directory named C:\Jy and downloaded
jython-21.class there. Of course, you can choose
to name and place the directory as it best suits you. On Unix-like
platforms, in particular, the directory name will more likely be
something like ~/Jy.
The Jython installer .class file is a
self-installing program. Open an MS-DOS Prompt window (or a shell
prompt on a Unix-like platform), change directory to
C:\Jy, and run your Java interpreter on the
Jython installer. Make sure to include directory
C:\Jy in the Java CLASSPATH.
With most releases of Sun's Java Development Kit
(JDK), for example, you can run:
C:\Jy> java -cp . jython-21
This runs a GUI installer that lets you choose destination directory
and options. If you want to avoid the GUI, you can use the
-o switch on the command line. The switch lets you
specify the installation directory and options directly on the
command line. For example:
C:\Jy> java -cp . jython-21 -o C:\Jython-2.1 demo lib source
installs Jython, with all optional components (demos, libraries, and
source code), in directory C:\Jython-2.1. The
Jython installation builds two small, useful command files. One, run
as jython (named jython.bat
on Windows), runs the interpreter. The other, run as
jythonc, compiles Python source into JVM
bytecode. You can add the Jython installation directory to your
PATH, or copy these command files into any
directory on your PATH.
You may want to use Jython with different JDKs on the same machine.
For example, while JDK 1.4 is best for most development, you may also
need to use JDK 1.1 occasionally in order to compile applets that can
run on browsers that support only Java 1.1. In such cases, you could
share a single Jython installation among multiple JVMs. However, to
avoid confusion and accidents, I suggest you perform separate
installations from the same Jython download on each JVM you want to
support. Suppose, for example, that you have JDK 1.4 installed in
C:\Jdk14 and JDK 1.1 installed in
C:\Jdk11. In this case, you could use the
commands:
C:\Jy> \Jdk14\java -cp . jython-21 -o C:\Jy21-14 demo lib source
C:\Jy> \Jdk11\java -cp . jython-21 -o C:\Jy21-11 demo lib source
With these installations, you could then choose to work off
C:\Jy21-14 most of the time (e.g., by placing it
in your PATH), and cd to
C:\Jy21-11 when you specifically need to compile
applets with JDK 1.1.
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