Implementing a Script Engine - Scripting in Java: Integrating with Groovy and JavaScript - page 269

Listing 8-4. Contents of the File Named javax.script.ScriptEngineFactory

#The factory class for the JKScript engine
com.jdojo.script.JKScriptEngineFactory

Why do you have to perform this step? You will package the javax.script.
ScriptEngineFactory file along with the class files for the JKScript engine in a JAR
file. The discovery mechanism for script engines searches for this file in the META-INF/
services directory in all JAR files in the CLASSPATH. If this file is found, its contents are
read and all script factory classes in this file are instantiated and included in the list of
script engine factories. Therefore, this step is necessary to make your JKScript engine
autodiscoverable by the ScriptEngineManager .

Packaging the JKScript Files
You need to package all files for the JKScript script engine in a JAR file named jkscript.
jar . You can name the file anything else as well. The following is the list of files with their
directories. Note that an empty manifest.mf file will work in this case:

com\jdojo\script\Expression.class •

com\jdojo\script\JKScriptEngine.class •

com\jdojo\script\JKScriptEngineFactory.class

•

META-INF\manifest.mf •

META-INF\services\javax.script.ScriptEngineFactory
You can create the jkscript.jar file manually by copying all of these files, except
the manifest.mf file, into a directory, say C:\build on Windows, and then executing the
following command from the C:\build directory:

•

C:\build> jar cf jkscript.jar com\jdojo\script\*.class META-INF\services\*.*

The jkscript.jar file is available in the src\JavaScripts directory in the
downloadable package for this topic. The downloadable source code contains a
NetBeans 8.0 project and the jkscript.jar file is added to the project's CLASSPATH.
If you run the engine from the included NetBeans IDE, you do not need to perform the
packaging and deploying steps to use the JKScript engine.

Using the JKScript Script Engine
It is time to test your JKScript script engine. The first and most important step is to
include the jkscript.jar , which you created the previous section, to the application
CLASSPATH. Once you have included the jkscript.jar file in your application
CLASSPATH, using JKScript is no different from using any other script engines.